Blood T1 Research Articles

In vivo whole‐blood T2 versus HbO2 calibration by modulating blood oxygenation level in the femoral vein through intermittent cuff occlusion

To investigate the feasibility of estimating calibration constants (K and T2o ) in vivo for converting whole-blood T2 to blood hemoglobin oxygen saturation (HbO2 ) according to the Luz-Meiboom model, 1/T2=1/T2o+K(1-HbO2)2, where K and T2o are relaxivity and transverse relaxation time of fully saturated blood, respectively. A range of HbO2 values was achieved in the superficial femoral vein with intermittent cuff occlusion in seven healthy adults (four males) to establish a calibration curve between blood T2 and HbO2 at 1.5T. HbO2 was derived via MR susceptometry, a technique previously validated, and the transverse relaxation time was quantified with an optimized T2 -prepared balanced steady-state free precession pulse sequence. To evaluate the accuracy of the in vivo calibration method, T2 and HbO2 were quantified in the superior sagittal sinus in six additional subjects and compared with susceptometry. Two sets of gender-specific calibration constants were derived, one for each gender corresponding to hematocrits of 0.47 ± 0.02 for males and 0.38 ± 0.01 for females, yielding K/T2o = 41 Hz/260 ms and 26 Hz/280 ms, respectively. The in vivo calibration returned physiologically plausible superior sagittal sinus SvO2 values (65 ± 5% HbO2 ), and there was no significant difference between the results from the two methods (average difference -0.3% HbO2 ). The results show feasibility of performing in vivo calibration for converting whole-blood T2 to HbO2 . The proposed approach bypasses the involved and cumbersome processes associated with in vitro calibration. Magn Reson Med 79:2290-2296, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

016 Uspio-enhanced CMR comprehensive methodological investigation and application in acute MI

Introduction Quantification of active myocardial inflammation may improve diagnosis, guide management and provide trial end-points for novel therapies. Ultrasmall particles of iron oxide (USPIO) are phagocytosed by activated leukocytes and USPIO-enhanced CMR is increasingly used to assess tissue inflammation. We aimed to; 1. Compare T2* imaging with T1 mapping, which is proposed as an alternative for ‘native’ cardiac iron measurement; 2. Determine whether imaging at a single time point post-USPIO is sufficient to detect active accumulation in tissue; 3. Determine whether USPIO signal from infarct and remote zones in acute myocardial infarction (MI) reflects active myocardial accumulation or passive ‘wash-through’ in oedematous myocardium. Methods Four healthy volunteers and six patients with acute MI underwent 1.5T CMR, including T1 and T2* mapping, before and at multiple time points following 4 mg/kg ferumoxytol. Results Normalised T2* of spleen, an organ with high active leukocyte activity, dropped post-USPIO and remained low over the study period (Figure 1), with no correlation seen between spleen T2* and blood T1 (rho=−0.43, p=0.875). In comparison, T1 recovery in spleen correlated strongly with T1 recovery in blood (rho=0.924, p In MI, absolute T2* values dropped and remained significantly lower in infarcted (15 vs 27ms, p Conclusions 0T2* is sensitive to active tissue accumulation of USPIO, likely because T2* reflects field gradients, such as those generated by compartmentalised (phagocytosed) USPIO. T1, which is due to short range dipolar interactions that reduce as USPIOs wash-out, simply tracks passive wash-through. T1 is therefore less suitable for detecting active leukocytes. Measuring T2* at a single time point post-USPIO is insufficient to determine tissue accumulation from passive wash-through. USPIO signal from infarct and remote zones in acute MI appears to genuinely reflect active myocardial accumulation, presumably due to phagocytosis by activated leukocytes.

006 Role of T1 mapping as a complementary tool to T2* for non-invasive cardiac iron overload assessment

AbstractBackground Iron overload-related heart failure is the principal cause of death in transfused Thalassemia Major1–2 and other iron overload patients. Linking cardiac siderosis measured by T2* to therapy improves outcome in Thalassemia Major. Aim of our study is to compare T1 mapping (Modified Lock Locker Inversion recovery, MOLLI) to dark (DB) and bright (BB) blood T2*3–4 in cardiac iron overload and to support the hypothesis that T1 mapping has higher sensibility to T2* for small amount of iron, which would make it a complementary tool to T2* in borderline iron overload patients.5–6 Methods In a prospectively large single centre study of 138 Thalassemia Major patients and 32 healthy controls, we compared MOLLI to DB and BB T2* acquired on an Avanto 1.5T scanner (Siemens Healthcare, Erlangen, Germany). Linear regression analysis was used to assess the association between DBT2* and either BBT2* and MOLLI, and the determination coefficient was computed in a log-log scale with moving windows to detect the point where this association decreases.Results The relationship between T2* (here DB) and MOLLI is described by a log-log linear regression, which can be split in three different slopes: 1) T2* low, <20ms: r2=0.92; 2) T2*=20–28 ms: r2=0.80; 3) T2*>28 ms, no relationship. All subjects with T2*<20 ms had low T1; of those with T2*>20 ms, 38% had low T1.Conclusions These data support the former proposal that T1 detects missed iron 1 in 3 subjects with normal T2* and that T1 mapping is a complementary tool for non-invasive assessment of cardiac iron. The clinical significance of a low T1, normal T2* should be further investigated. A trend toward LV end diastolic volume increase was observed in the patients with low T1 and normal T2* at 24 months, but the sample was too small to be analysed (n=9).References. Modell B, Khan M, Darlison M, Westwood MA, Ingram D, Pennell DJ. Improved survival of thalassaemia major in the UK and relation to T2* cardiovascular magnetic resonance. J Cardiovasc Magn Reson2008;10:42.. Carpenter JP, Pennell DJ. On T2* Magnetic Resonance and Cardiac Iron. Circulation2011;14:1519–28.. Wood JC, Otto-Duessel M, Aguilar M, et al. Cardiac Iron Determines Cardiac T2*, T2, and T1 in the Gerbil Model of Iron Cardiomyopathy. Circulation2005;112(4):535–543.. Carpenter JP, He T, Kirk P, et al. Calibration of myocardial T2 and T1 against iron concentration. J Cardiovasc Magn Reson2014;16:62.. Alam MH, Auger D, Smith GC, et al. T1 at 1.5T and 3T compared with conventional T2* at 1.5T for cardiac siderosis. J Cardiovasc Magn Reson. 2015;17:102.. Messroghli DR, Radjenovic A, Kozerke S, Higgins DM, Sivananthan MU, Ridgway JP. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magn Reson Med2004;52(1):141–6.. Alam MH, Auger D, Smith GC, et al. T1 at 1.5T and 3T compared with conventional T2* at 1.5T for cardiac siderosis. J Cardiovasc Magn Reson2015;17(24):102.Download figure Open in new tab Download powerpoint Abstract 006 Figure 1

The impact of inspired oxygen levels on calibrated fMRI measurements of M, OEF and resting CMRO2 using combined hypercapnia and hyperoxia.

Recent calibrated fMRI techniques using combined hypercapnia and hyperoxia allow the mapping of resting cerebral metabolic rate of oxygen (CMRO2) in absolute units, oxygen extraction fraction (OEF) and calibration parameter M (maximum BOLD). The adoption of such technique necessitates knowledge about the precision and accuracy of the model-derived parameters. One of the factors that may impact the precision and accuracy is the level of oxygen provided during periods of hyperoxia (HO). A high level of oxygen may bring the BOLD responses closer to the maximum M value, and hence reduce the error associated with the M interpolation. However, an increased concentration of paramagnetic oxygen in the inhaled air may result in a larger susceptibility area around the frontal sinuses and nasal cavity. Additionally, a higher O2 level may generate a larger arterial blood T1 shortening, which require a bigger cerebral blood flow (CBF) T1 correction. To evaluate the impact of inspired oxygen levels on M, OEF and CMRO2 estimates, a cohort of six healthy adults underwent two different protocols: one where 60% of O2 was administered during HO (low HO or LHO) and one where 100% O2 was administered (high HO or HHO). The QUantitative O2 (QUO2) MRI approach was employed, where CBF and R2* are simultaneously acquired during periods of hypercapnia (HC) and hyperoxia, using a clinical 3 T scanner. Scan sessions were repeated to assess repeatability of results at the different O2 levels. Our T1 values during periods of hyperoxia were estimated based on an empirical ex-vivo relationship between T1 and the arterial partial pressure of O2. As expected, our T1 estimates revealed a larger T1 shortening in arterial blood when administering 100% O2 relative to 60% O2 (T1LHO = 1.56±0.01 sec vs. T1HHO = 1.47±0.01 sec, P < 4*10−13). In regard to the susceptibility artifacts, the patterns and number of affected voxels were comparable irrespective of the O2 concentration. Finally, the model-derived estimates were consistent regardless of the HO levels, indicating that the different effects are adequately accounted for within the model.

T1 and ECV Mapping in Myocardial Disease

T1 mapping using cardiovascular magnetic resonance (CMR) introduces novel techniques for myocardial tissue characterization to detect and quantify disease processes occurring at the microscopic level. Even though T1 mapping has limited spatial resolution, cellular and molecular changes occurring within each voxel can affect the aggregate T1 signal rendering them quantifiable. The estimated T1-based parameters quantified on a “map” demonstrate the spatial localization of these changes whereby each pixel expresses the quantitative value of that parameter. This quantification permits detection of diffuse disease even if it is not directly visible. Rather than relying on nonspecific functional measures, T1 mapping focuses on intrinsic changes of myocardial composition that advances understanding about specific disease pathways. These changes in myocardial tissue composition inform diagnosis and prognosis. T1 mapping encompasses two key parameters: native (i.e., precontrast) T1 and extracellular volume fraction (ECV) derived from additional postcontrast T1 and blood T1 measurements. These advances introduce new tools to detect focal and diffuse myocardial derangements occurring in cardiac disease that can be otherwise difficult to detect. T1 and ECV mapping foster precision medicine and personalized care, promising to improve patient outcomes through targeted therapy. Capitalizing on the opportunities introduced by T1 mapping and ECV requires further investigation.

Assessing the effects of subject motion on T2 relaxation under spin tagging (TRUST) cerebral oxygenation measurements using volume navigators.

Subject motion may cause errors in estimates of blood T2 when using the T2 -relaxation under spin tagging (TRUST) technique on noncompliant subjects like neonates. By incorporating 3D volume navigators (vNavs) into the TRUST pulse sequence, independent measurements of motion during scanning permit evaluation of these errors. The effects of integrated vNavs on TRUST-based T2 estimates were evaluated using simulations and in vivo subject data. Two subjects were scanned with the TRUST+vNav sequence during prescribed movements. Mean motion scores were derived from vNavs and TRUST images, along with a metric of exponential fit quality. Regression analysis was performed between T2 estimates and mean motion scores. Also, motion scores were determined from independent neonatal scans. vNavs negligibly affected venous blood T2 estimates and better detected subject motion than fit quality metrics. Regression analysis showed that T2 is biased upward by 4.1 ms per 1 mm of mean motion score. During neonatal scans, mean motion scores of 0.6 to 2.0 mm were detected. Motion during TRUST causes an overestimate of T2 , which suggests a cautious approach when comparing TRUST-based cerebral oxygenation measurements of noncompliant subjects. Magn Reson Med 78:2283-2289, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

A Young Woman with Sudden Hemiparesis

Abstract: Stroke related to cerebral vasospasm may have the same appearance that ischemic stroke of other causes. The correct diagnosis is critical to avoid inappropriate treatments as thombolysis and anticoaglant therapy. In this case, a previous young healthy woman presented with acute onset of right-sided hemiplegia and expressive aphasia. Interpretation of Magnetic Resonance Images was challenging: acute ischemia, severe vasospasm, no signs of subarachnoid hemorrhage or intra-arterial thrombi, no evidence of cervical artery dissection. Cerebral angiography allowed to conclude that a ruptured small aneurysm was responsible for stroke, related to a spasm at the 7th day of aneurysm rupture concomitant of neck pain. The predictive MRI signs and the factors that contributed for the good outcome of a symptomatic vasospasm are discussed Case Presentation; A 30-year-old woman, without risk factors, presented with acute onset of right-sided deficit and expressive aphasia for potential thrombolysis.The interpretation of MRI was challenging. Various MRI findings help determine the etiology of stroke. A previously healthy 30-year-old woman presented to the stroke center for potential thrombolysis. She had presented sharp neck pain one week ago and neurological examination was unremarkable. She awoke at 8 am with right motor deficit. On arrival, 4 hours later, she was mutic with a Glasgow Coma Scale score of 15. She was normotensive (110/75 mmHg) with right-sided hemiplegia. Electrocardiogram did not demonstrate any arrthymia or other abnormality Emergent magnetic resonance imaging (MRI) of the brain displayed on diffusion-weighted imaging MRI (DWI) (Figure 1) and apparent coefficient diffusion map, (within 4 hours from onset), an acute ischemic stroke in the superficial territory of left middle cerebral artery (MCA), with normal fluid attenuated inversion recovery (FLAIR) except vessel hyperintensities (FVHs) proximal and distal to the sylvian fissure (Figures 2 and 3). T2* did not reveal any thrombus or hemorrhage. The presence of hyperintensity on DWI without corresponding hyperintensity on FLAIR, called “DWI-FLAIR mismatch indicate that the patient is likely within the time window for thrombolysis, Magnetic resonance angiography (MRA) visualized a severe vasospasm of the left terminal internal carotid artery and left MCA (M1 segment) (Figure 4). Intracranial and extracranial MRA was otherwise unremarkable, especially no dissection of the left carotid artery was identified, as also demonstrated by three-dimensional black blood (3D CUBE) T1 sequence. Diagnosis: Aneurysm rupture presenting as delayed ischemic stroke related to severe vasospasm Discussion: The interpretation of this imaging is challenging. Various MRI findings help determine the etiology of stroke and patient selection for acute ischemic stroke treatment (thrombolysis) [1]. The most common mechanisms of stroke in young population are cardioembolism and patent foramen ovale, and dissection of the cervical arteries. The first cause can be suspected when patients present acute multiple territorial lesions or a single large cortical and subcortical lesion on DWI and patent foramen ovale, another source of cardioembolism, usually causes small cortical lesions in vertebro-basilar territory. The presence of hypointense signals with blooming artifacts in the arterial system on T2* sequence (susceptible vessel sign) assess the presence of intra-arterial thrombi, usually associated with cardioembolic stroke. In this unusual presentation of stroke in a young patient without any risk factor, the absence of visualization of intra-arterial thrombus on T2* sequence and of carotid artery dissection (mural hematoma) on dedicated 3D CUBE sequence and the presence of a long spasm allow to conclude that a ruptured aneurysm was responsible for stroke, related to the spasm that occurred at the 7th day of rupture contemporary of neck pain. Seven days after the aneurysm rupture, a subarachnoid hemorrhage could not be identified on CT, nor on FLAIR and T2* MRI sequences : even if FLAIR sequence is more sensitive than CT and over a longer time period, the patient underwent MRI to late for examination at the 7th day [2]. Cerebral angiography identified a small aneurysm of the left anterior choroidal artery (Figure 5). Patients with DWI-FLAIR mismatch are likely to be within the time of adequate treatment. Endovascular treatment was performed using mechanical angioplasty and coiling. At 3-month follow-up, the patient was asymptomatic and MRA was normal (Figure 6). FHVs are imaging markers of both occlusion or narrowing when proximal to the ischemic core and of collateral system when distal. When present outside the ischemic core, they are associated with good outcome [3]. In the present case, the presence of collateral flow objective by FHV, an early treatment and the absence of risk factors contributed for the good outcome of a symptomatic vasospasm [4,5].

Role of T1 Mapping As a Complementary Tool to T2* for Cardiac Iron Overload Assessment

Introduction. Iron overload-related heart failure is the principal cause of death in transfused Thalassemia Major (TM) (Modell B, Cardiovasc Magn Reson 2008;10:42-48). Iron toxicity is dose dependent so a strategy of chelation therapy titration (Kirk P, Circ 2009;120:1961-1968) before the onset of left ventricle (LV) impairment changes outcomes (Alpendurada F, Eur Heart J. 2010; 31:1648-54). The presence of iron in tissue detectably changes the magnetic properties of water, T1, T2 and T2*, as validated against tissue in animal and human models (Carpenter JP, Circ 2011;14:1519-28). T2*, the most used technique, is susceptible to non-iron influence (susceptibility artefact) and has low accuracy for high and low iron levels (Carpenter JP, J Cardiovasc Magn Reson. 2014;12:16-62). T1 mapping could complement T2* as it appears to have superior reproducibility and to detect mild iron missed by T2* (Abdel-Gadir A. J Cardiovasc Magn Reson. 2015;17(Suppl1):P312. Sado DM, J Magn Reson Imaging. 2015;41:1505-11), but studies to date have been small and not using state-of-the-art sequences.Methods. In a prospectively single centre study of 138 TM patients and 32 healthy volunteers (HV) (no known medical conditions, normal CMR scan), we compared T1 mapping (Modifier Lock Locker Inversion sequence - MOLLI - Siemens Works in progress 448B) to the gold-standard dark (DB) and bright (BB) blood T2*, acquired on an Avanto 1.5T (Siemens Healthcare, Erlangen, Germany). For both T2* sequences, a single 10mm mid-ventricular short axis slice was imaged at 8 echo-times (2.58ms to 18.19ms, increment 2.23ms), flip angle=20¡, FOV read/phase=400mm/56,3%. The same slice was used for T1 images (thickness 6mm, distance factor=67%, FOV read/phase=360/75%, TR=740, TE=1.13, with motion correction for the in-line map generation).Results and discussion.All participants provided informed consent.Table1 illustrates patients' and HV's details.T2* was defined normal under the cutpoint value of 20ms. T1 normal range, defined by the HV cohort was 918-1015ms (the 2.5-97.5 quantiles with CI 95%). For DBT2*<20ms, both BBT2* and T1 mapping were broadly indistinguishable from DBT2* (DBT2* vs BBT2* R2=0.95; DBT2* vs T1 R2=0.92; all p<0.001). All subjects with low DBT2* (n=24, 17.4%) had low T1; 52 patients had normal DBT2* but low T1 mapping, i.e. 38% patients were reclassified from normal to iron loaded by T1. The relationship between DBT2* and MOLLI was described by a log-log linear regression (R2=0.80, p<0.001). Upper panel of Fig1 shows T1 vs DBT2* correlation over a 20ms window as the window moves by 1ms at a time on X-axis (so at X-axis point ’n’, the Y-value is the R2 of the correlation of DBT2* vs T1 over the range n-to-n+20ms). As shown by lower panel of Fig1, three domains can be observed: strong relationship in the T2*=0-20ms range (R2=0.92, p<0.001); good relationship in the 21-28ms range, where the curve depicts a plateau (R2=0.80-0.77, p<0.001) and no relationship above 28ms. Given the conservative approach used to set T2* normality as above 20ms (Carpenter JP, Circ 2011;14:1519-28), the evidence that T2* SD values increase even for borderline T2* mean values (~20ms) (Anderson LJ, Eur Heart J. 2001;22:2171-9), and that 39% of normal T2* subjects have a low T1, we support prior suggestions that T1 is detecting mild iron in most of the subjects with DBT2*=20-28ms, missed by T2* as the threshold has had to be set too low for sensitivity reasons (Sado DM, J Magn Reson Imaging. 2015;41:1505-11). T1 mapping is thus a useful complementary tool to T2* both for clinical and research purposes. The reported reproducibilities of T1 square for power calculations and would translate into 6.25 to 49 times more power in studies to detect iron change (Alam MH, J Cardiovasc Magn Reson. 2015;24:17-102). Colour maps make iron instantly visible and add a confirmation step. Whether mild iron missed by T2* is important is unclear. In our cohort, 24-months follow-up was available for 9 patients with normal DBT2* and low T1. Although no statistical consideration is possible due to the small number, in those patients an increase in LV end diastolic volume was observed (from 78±18ml to 84±15ml), suggesting possible cardiotoxicity of even mild amount of iron. Further work is needed, especially in frail cohorts like children starting chelation and around pregnancy. [Display omitted] [Display omitted] DisclosuresMoon:gsk: Consultancy; Genzyme: Research Funding; Shire: Membership on an entity's Board of Directors or advisory committees. Cappellini:Novartis: Membership on an entity's Board of Directors or advisory committees; Genzyme-Sanofi: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

Hemoglobin S Exhibits Distinct MRI Oximetry Calibration in Vitro

Cerebral oxygen extraction fraction (OEF) is a powerful biomarker that could be used to stratify cerebrovascular morbidity in patients with sickle cell disease (SCD). Recently, several MRI intravascular oximetry techniques have demonstrated early feasibility in non-invasively quantitating OEF. Critical to this technique is the use of empirically derived calibrations that convert the measured magnetic relaxation property, T2, into oxygen saturation. Previous work demonstrated a strong hematocrit and saturation dependence on T2 and our prior work extended early results to hematocrit ranges common in patients with chronic anemia1. Despite improvements in calibration models, it remains an unanswered question whether the unique hemorheologic properties of hemoglobin S (HbS) containing red cells will give rise to fundamentally distinct magnetic properties compared to healthy, hemoglobin A (HbA) cells.Methods: All studies were performed on at CHLA under an IRB protocol with consent/assent. The blood of 11 subjects with sickle cell disease were studied (6 Male, 5 Female, aged 25.4 ± 14.5 years). Six had HbSS, three had HbSC, and two had HbSB0). Three of the subjects were on chronic transfusion therapy (2HbSS, 1 HbSB0). Two tablespoons of blood was drawn for the antecubital vein and stored at 4°C until analysis. For analysis, blood was placed in a custom built imaging apparatus and heated to 37° C. Oxygen level was measured with a hemoximeter and T2 was measured within a 3T Philips scanner. Following the T2 measurement blood was removed from the imaging apparatus and desaturated in a temperature controlled chamber using a membrane oxygenator and 5% CO2 and 95% N2 gas mixture. MRI T2 measurements and deoxygenation were repeated until a blood saturation level of ~30% was reached. T2 was measured with a phase cycled, CPMG sequence with 0, 4, 8 16 inversions pulse and a tau of 10ms. Monoexponetial fitting was used to derive T2.Results: Our previous work using a similar system and HbA blood demonstrated a highly reproducible relationship linking T2 to hematocrit and oxygen saturation (Y) as follows:R2= 1/T2 = A1*HCT*(1-Y)2 + A2*(1-Y)2 + A3*HCT + A4where the coefficients A1, A2, A3, and A4 were fit to data from a broad range of hematocrit and oxygen saturation values. In blood from sickle cell patients, we found that the A1 and A3 terms were zero. Thus the calibration curve was essentially independent of hematocrit. Figure 1 shows the tight relationship between hematocrit and 1/T2 for HbA could not be reproduced in HbS blood. In Figure 2, 1/T2 maintained a tight relationship (R2=.981) with (1-Y)2. The slope of 1/T2 and (1-Y)2was higher in HbS blood compared to HbA. There was also a positive relationship between HbS% and the residual of (1-Y)2 and R2 however this is was a weak effect (R2=0.057).Discussion: We found that the T2 of HbS containing red cells is distinct from the healthy HbA containing cells. This work has clinical implications for intravascular MRI oximetry performed in patients with sickle cell disease2 in that neglecting the magnetic differences between HbA and HbS may result in a 9.5%± 2.8% average bias in absolute saturation at a HCT of 32% . Interestingly, we were unable find a difference across sickle phenotypes and only small differences in transfused vs nontransfused patients. We suspect that irreversibly sickled cells, even few in number, will greatly influence the local magnetic field and shorten the T2 of sickle blood. It remains to be shown whether the in vitro conditions of this experiment are applicable to in vivo condition more broadly. In-vivo cross-validation studies are ongoing.1). Bush et al. MRM 20162). Jordan LC et al. Brain 2016Jordan LC, Gindville MC, Scott AO, et al. Non-invasive imaging of oxygen extraction fraction in adults with sickle cell anaemia. Brain2016;139(Pt 3):738-5 [Display omitted] [Display omitted] DisclosuresWood:World Care Clinical: Consultancy; Celgene: Consultancy; World Care Clinical: Consultancy; Vifor: Consultancy; Vifor: Consultancy; Ionis Pharmaceuticals: Consultancy; Ionis Pharmaceuticals: Consultancy; Celgene: Consultancy; AMAG: Consultancy; AMAG: Consultancy; Apopharma: Consultancy; Apopharma: Consultancy; Biomed Informatics: Consultancy; Biomed Informatics: Consultancy.

Identification of a Novel Chromosomal Translocation t(11;16)(q23;q22) Fusing MLL to Enhancer of mRNA Decapping (EDC)-4 in Smoldering Acute Myeloid Leukemia

Abstract Background: Translocations involving the MLL gene located on chromosome 11q23 are usually found in de novo acute myeloid leukemia (AML) and generally confer a dismal prognosis unless the AF9 gene is involved (Döhner et al., Blood 2010;115:453-74). MLL can be fused to multiple different genes, resulting in the large and growing "MLL recombinome" (Meyer et al., Leukemia 2013;27:2165-76). Thus far, only two genes encoding proteins that are part of the mRNA decapping protein complex (i.e., DCP1A, DCPS) have been described as rarely being fused to MLL. Here, we describe an AML with an indolent disease course arising from myelodysplastic syndrome (MDS) that disclosed a unique MLL fusion with another component of the mRNA decapping complex, i.e., EDC4. Patient and Methods: Briefly, a 55 year-old female patient presented with an MDS [timepoint (t) -1] that within 10 months progressed to an AML with 2% blood and 40% bone marrow myeloblasts (t0). The patient refused treatment beyond supportive care. Six months later, a marked blast expansion of 80% was detectable in the blood (t1). The patient received 5 cycles of decitabine (t2, cycle 5), followed by 3 months of hydroxyurea (t3). Samples were depleted from CD3+ cells via MACS; CD3+ cells served as germline control. RNA sequencing libraries were prepared using the NEBNext Ultra RNA Library Prep Kit for Illumina (New England Biolabs), and the SureSelect Human All Exon v5 kit (Agilent Technologies) was used for exome capturing from gDNA. Next generation sequencing was performed on an Illumina Hiseq 2500. The analyses were performed as previously described (Kataoka et al. Nature Genetics 2015;47:1304-15, Becker et al. Blood 2014;123:1883-6). NOD scid gamma mice were used as hosts for patient derived tumor xenografts (PDX). Results: Standard metaphase cytogenetics at the diagnosis of AML (t0) revealed a previously undescribed translocation involving the MLL gene, i.e., t(11;16)(q23;q22), as the sole cytogenetic abnormality. The unknown fusion partner on chromosome 16 was identified by RNA-sequencing as the EDC4 gene (a.k.a. Ge-1), which encodes a key scaffold protein of the mRNA decapping complex; the fusion was confirmed by PCR on cDNA. The translocation led to the in-frame fusion of MLL exon 13 to EDC4 exon 6 which was linked by 19 nucleotides from EDC4 intron 5. The predicted amino acid sequence of the linker was ALNTLLR. Further analyses including exome sequencing on the samples collected over the disease course demonstrated STAG2 as a potential founder mutation that was already present during the MDS (t-1) and persisted throughout the disease course at variant allele frequencies (VAFs) of approximately 45-50%. At the time of transformation to AML (t0), the MLL-EDC4 and two RAS mutations (KRAS p.G13D, NRAS p.G12C) were detectable. Towards the terminal phase (t3), the RAS mutations disappeared and a clone that acquired a mutation in the FLT3 tyrosine kinase domain (TKD; p.D835V; VAF 43%) expanded. Primary blasts from the patient engrafted in NOD scid gamma mice and established a stable PDX serial transplantation mouse model used for drug testing. Conclusions: This report provides the first demonstration of an MLL-EDC4 in-frame fusion, with potential cooperativity with a founder mutation in the STAG2 splicing factor gene during the transformation of MDS to AML and the additional acquisition of a FLT3-TKD mutation during disease progression. RNA sequencing proved to be a very feasible approach to identify novel fusion partners of known oncogenes such as MLL. Disclosures Becker: BMS: Honoraria; Novartis: Honoraria. Kataoka:Yakult: Honoraria; Boehringer Ingelheim: Honoraria; Kyowa Hakko Kirin: Honoraria. Schüler:Oncotest GmbH: Employment. Ogawa:Kan research institute: Consultancy, Research Funding; Sumitomo Dainippon Pharma: Research Funding; Takeda Pharmaceuticals: Consultancy, Research Funding. Lübbert:Janssen-Cilag: Other: Travel Funding, Research Funding; Celgene: Other: Travel Funding; Ratiopharm: Other: Study drug valproic acid.

Beta-Thalassemia (BT) Prevalence and Treatment Patterns in Italy: A Survey of Treating Physicians

Background: BT is an important public-health challenge in Italy. Seminal work has begun to better characterize disease prevalence, treatment patterns, and institutional capabilities within Italy.Objective: Evaluation of current BT prevalence and treatment in Italy was done using proprietary IMS Health hospital audit data as the basis of a targeted survey of hematologists, pediatricians, and internists treating BT. We estimated the prevalence and distribution of patients with transfusion-dependent (TD) BT major (BT-M) and intermedia (BT-I), and non-transfusion-dependent BT (NTD BT), and characterized current treatment patterns.Methods: A preliminary list of possible BT-treating centers was extracted from the IMS Health audit of hospitals and treatment centers across Italy, covering 656 public hospitals and accounting for 205,021 beds (85% of hospital capacity in Italy).The IMS Health hospital audit also included 95% of the pharmaceutical Direct Patient Distribution channel. This list was reviewed to identify centers receiving iron-chelating agents, thus identifying a total of 365 potentially BT-treating hospitals. One hematologist or pediatrician in each potential hospital ward was contacted by telephone. The physician was asked to provide details about the number of TD BT-M, TD BT-I, and NTD BT patients managed in their ward. In case of refusal to provide the required information, telephone or in-person interviews were organized with other specialists in the same facility. We identified 124 treatment centers, 114 of which were successfully surveyed (92% completed the survey). Subsequently we used a web-based questionnaire to ask a geographically stratified sample of 60 treating physicians about general treatment patterns, with a focus on potential drivers of health-care resource utilization. Responding physicians each referenced 3-4 records for patients currently under their care to inform their responses to our survey, and 205 records were referenced in total: 162 TD and 43 NTD patients.Results: In the 114 treatment centers surveyed, a total of 5,748 TD BT patients under regular treatment were reported, plus 1,296 additional patients receiving occasional treatment (NTD BT). Distribution of TD patients was heterogeneous, with the highest prevalence in Sicily, Sardinia, and Puglia. These regions each had > 500 TD patients and hosted in total 3,051 TD patients (Table). National patient volume was highly concentrated with the 7 largest centers managing 1,766 TD patients.Based on the information in 205 patient records, complete blood count, ferritin level, echocardiography, and T2*-weighted MRI were the tests most commonly performed in the preceding 12 months. Of 162 TD patient records reviewed, 83 patients required 1-2 units of red blood cells per month, while 78 patients required ≥ 3 units per month (this information was not captured in 1 patient record). Deferasirox was the most commonly administered chelation treatment in TD patients, prescribed to 109 of 162 patients. Most TD patients (n = 126) had previously had a change of iron chelation treatment; 72 of these switched from deferoxamine to another agent. In-patient hospitalizations were estimated at 9 days/year, 7 days/year, and 4 days/year for TD BT-M, TD BT-I, and NTD BT patients, respectively. Endocrine pathologies were the most commonly reported comorbidity in all groups; 36 patients required medical treatment. Hepatitis C virus infection and hepatic and cardiac complications were also reported.Conclusions: Prevalence of BT is regionally focused and likely to consume significant health-care resources for management of the disease and associated comorbidities. Although the telephone and web surveys used for our project were not designed to be a clinical trial, we were able to assess practices by a number of physicians (n = 60) for patients (n = 205) that were representative of the distribution of BT across Italy. We also screened the overall BT caseload of up to 365 potentially BT-treating centers in the country. Our survey complements recent work to understand the burden of this disease in Italy. [Display omitted] DisclosuresAngelucci:Novartis Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees. Burrows:Celgene Corporation: Research Funding; IMS Health s.r.l.: Employment. Losi:IMS Health: Employment; Celgene Corporation: Research Funding. Bartiromo:Celgene Corporation: Employment, Equity Ownership. Hu:Celgene Corporation: Employment, Equity Ownership.

Blood correction reduces variability and gender differences in native myocardial T1 values at 1.5\xa0T cardiovascular magnetic resonance \u2013 a derivation/validation approach

BackgroundMyocardial native T1 measurements are likely influenced by intramyocardial blood. Since blood T1 is both variable and longer compared to myocardial T1, this will degrade the precision of myocardial T1 measurements. Precision could be improved by correction, but the amount of correction and the optimal blood T1 variables to correct with are unknown. We hypothesized that an appropriate correction would reduce the standard deviation (SD) of native myocardial T1.MethodsConsecutive patients (n = 400) referred for CMR with known or suspected heart disease were split into a derivation cohort for model construction (n = 200, age 51 ± 18 years, 50% male) and a validation cohort for assessing model performance (n = 200, age 48 ± 17 years, 50% male). Exclusion criteria included focal septal abnormalities. A Modified Look-Locker inversion recovery sequence (MOLLI, 1.5 T Siemens Aera) was used to acquire T1 and T1* maps. T1 and T1* maps were used to measure native myocardial T1, and blood T1 and T1*. A multivariate linear regression correction model was implemented using blood measurement of R1 (1/T1), R1* (1/T1*) or hematocrit. The correction model from the derivation cohort was applied to the validation cohort, and assessed for reduction in variability with the F-test.ResultsBlood [LV + RV] mean R1, mean R1* and hematocrit correlated with myocardial T1 (Pearson’s r, range 0.37 to 0.45, p < 0.05 for all) in both the derivation and validation cohorts respectively, suggesting that myocardial T1 measurements are influenced by intramyocardial blood. Mean myocardial native T1 did not differ between the derivation and validation cohorts (1030 ± 42.6 ms and 1023 ± 45.2 ms respectively, p = 0.07). In the derivation cohort, correction using blood mean R1 and mean R1* yielded a decrease in myocardial T1 SD (45.2 ms to 36.6 ms, p = 0.03).When the model from the derivation cohort was applied to the validation cohort, the SD reduction was maintained (39.3 ms, p = 0.049). This 13% reduction in measurement variability leads to a 23% reduction in sample size to detect a 50 ms difference in native myocardial T1.ConclusionsCorrecting native myocardial T1 for R1 and R1* of blood improves the precision of myocardial T1 measurement by ~13%, and could consequently improve disease detection and reduce sample size needs for clinical research.

CMR-based blood oximetry via multi-parametric estimation using multiple T2 measurements

BackgroundMeasurement of blood oxygen saturation (O2 saturation) is of great importance for evaluation of patients with many cardiovascular diseases, but currently there are no established non-invasive methods to measure blood O2 saturation in the heart. While T2-based CMR oximetry methods have been previously described, these approaches rely on technique-specific calibration factors that may not generalize across patient populations and are impractical to obtain in individual patients. We present a solution that utilizes multiple T2 measurements made using different inter-echo pulse spacings. These data are jointly processed to estimate all unknown parameters, including O2 saturation, in the Luz-Meiboom (L-M) model. We evaluated the accuracy of the proposed method against invasive catheterization in a porcine hypoxemia model.MethodsSufficient data diversity to estimate the various unknown parameters of the L-M model, including O2 saturation, was achieved by acquiring four T2 maps, each at a different τ180 (12, 15, 20, and 25 ms). Venous and arterial blood T2 values from these maps, together with hematocrit and arterial O2 saturation, were jointly processed to derive estimates for venous O2 saturation and other nuisance parameters in the L-M model. The technique was validated by a progressive graded hypoxemia experiment in seven pigs. CMR estimates of O2 saturation in the right ventricle were compared against a reference O2 saturation obtained by invasive catheterization from the right atrium in each pig, at each hypoxemia stage. O2 saturation derived from the proposed technique was also compared against the previously described method of applying a global calibration factor (K) to the simplified L-M model.ResultsVenous O2 saturation results obtained using the proposed CMR oximetry method exhibited better agreement (y = 0.84× + 12.29, R2 = 0.89) with invasive blood gas analysis when compared to O2 saturation estimated by a global calibration method (y = 0.69× + 27.52, R2 = 0.73).ConclusionsWe have demonstrated a novel, non-invasive method to estimate O2 saturation using quantitative T2 mapping. This technique may provide a valuable addition to the diagnostic utility of CMR in patients with congenital heart disease, heart failure, and pulmonary hypertension.

Aneurysmal wall imaging in a case of cortical superficial siderosis and multiple unruptured aneurysms

We report a case of interhemispheric and bifrontal cortical superficial siderosis in association with two intracranial aneurysms. The patient had no clinical history suggestive of aneurysm rupture, no feature of...

Pulmonary dysfunction in thalassaemia major: is there any relationship with body iron stores?

Although pulmonary function abnormalities in thalassaemia major (TM) were described in 1980, the pathogenetic mechanism is not clear and data are contradictory, probably because of study heterogeneity and the multifactorial nature of the pathogenesis. We retrospectively analysed 73 adult TM patients to evaluate the prevalence of pulmonary dysfunction in adult TM and investigate relationships with iron load. All patients underwent body plethysmography and carbon monoxide diffusion (DLCO) was assessed in 63, in addition to blood tests, echocardiogram and T2* myocardial and liver magnetic resonance imaging. Restrictive lung disease was present in 26 (35·6%) patients. Serum ferritin levels were higher in patients with restrictive pattern (1526μg/l vs. 975μg/l, P=0·05). Restrictive lung disease did not correlate with cardiac or liver iron overload. However, considering only patients with serum ferritin >2500μg/l, those with restrictive pattern also had heart (T2* 14·28±9·99ms vs. 31·59±7·43ms) and liver iron overload (LIC 16·02±8·44mg vs. 5·02±2·69mg Fe/g dry weight) compared to those without restrictive pattern. Twenty-five patients (39·7%) had decreased DLCO. No correlation was observed with iron parameters. In our data restrictive pattern was predominant; we observed a relationship with serum ferritin levels suggesting that iron, particularly its chronic effect, could play a role in the pathogenesis of pulmonary disease.

Black-blood native T1 mapping: Blood signal suppression for reduced partial voluming in the myocardium.

To study the feasibility of black-blood contrast in native T1 mapping for reduction of partial voluming at the blood-myocardium interface. A saturation pulse prepared heart-rate-independent inversion recovery (SAPPHIRE) T1 mapping sequence was combined with motion-sensitized driven-equilibrium (MSDE) blood suppression for black-blood T1 mapping at 3 Tesla. Phantom scans were performed to assess the T1 time accuracy. In vivo black-blood and conventional SAPPHIRE T1 mapping was performed in eight healthy subjects and analyzed for T1 times, precision, and inter- and intraobserver variability. Furthermore, manually drawn regions of interest (ROIs) in all T1 maps were dilated and eroded to analyze the dependence of septal T1 times on the ROI thickness. Phantom results and in vivo myocardial T1 times show comparable accuracy with black-blood compared to conventional SAPPHIRE (in vivo: black-blood: 1562 ± 56 ms vs. conventional: 1583 ± 58 ms, P = 0.20); Using black-blood SAPPHIRE precision was significantly lower (standard deviation: 133.9 ± 24.6 ms vs. 63.1 ± 6.4 ms, P < .0001), and blood T1 time measurement was not possible. Significantly increased interobserver interclass correlation coefficient (ICC) (0.996 vs. 0.967, P = 0.011) and similar intraobserver ICC (0.979 vs. 0.939, P = 0.11) was obtained with the black-blood sequence. Conventional SAPPHIRE showed strong dependence on the ROI thickness (R2 = 0.99). No such trend was observed using the black-blood approach (R2 = 0.29). Black-blood SAPPHIRE successfully eliminates partial voluming at the blood pool in native myocardial T1 mapping while providing accurate T1 times, albeit at a reduced precision. Magn Reson Med 78:484-493, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Influence of spatial resolution and contrast agent dosage on myocardial T1 relaxation times.

Our aim was to study the influence of small variations in spatial resolution and contrast agent dosage on myocardial T1 relaxation time. Twenty-nine healthy volunteers underwent cardiovascular magnetic resonance at 3T twice, including a modified look-locker inversion recovery (MOLLI) technique-3(3)3(3)5-for T1 mapping. Native T1 was assessed in three spatial resolutions (voxel size 1.4×1.4×6, 1.6×1.6×6, 1.7×1.7×6mm3), and postcontrast T1 after 0.1 and 0.2mmol/kg gadobutrol. Partition coefficient was calculated based on myocardial and blood T1. T1 analysis was done per segment, per slice, and for the whole heart. Native T1 values did not differ with varying spatial resolution per segment (p=0.116-0.980), per slice (basal: p=0.772; middle: p=0.639; apex: p=0.276), and globally (p=0.191). Postcontrast T1 values were significantly lower with higher contrast agent dosage (p<0.001). The global partition coefficient was 0.43±0.3 for 0.2 and 0.1mmol gadobutrol (p=0.079). Related to the tested MOLLI technique at 3T, very small variations in spatial resolution (voxel sizes between 1.4×1.4×6 and 1.7×1.7×6mm3) remained without effect on the native T1 relaxation times. Postcontrast T1 values were naturally shorter with higher contrast agent dosage while the partition coefficient remained constant. Further studies are necessary to test whether these conclusions hold true for larger matrix sizes and in larger cohorts.

Fast measurement of blood T1 in the human carotid artery at 3T: Accuracy, precision, and reproducibility.

To develop a fast protocol for measuring T1 values in the internal carotid artery (ICA), to validate this technique with in vitro measurements, and to evaluate its reproducibility. A modified Look-Locker sequence was optimized to enable rapid determination of T1 in the ICA at 3T. T1 values from the ICA were compared with in vitro measurements on individually sampled venous blood oxygenated to arterial levels. A test-retest reproducibility study was also conducted. The group-averaged arterial blood T1 value was 1908 ± 77 ms for six women (hematocrit = 0.39 ± 0.03) and 1785 ± 55 ms for seven men (hematocrit = 0.45 ± 0.02), which is 100-200 ms longer than the widely adopted value obtained from bovine blood experiments. The arterial T1 value per subject correlated significantly with individual hematocrit values. The intrasession and intersession coefficients of variation were 1.1% and 2.1%, respectively, indicating good precision and reproducibility of our method. Reasonable agreement was observed between the in vivo and in vitro results with a correlation coefficient of 0.78. The proposed method can provide fast arterial T1 measurement on individual subjects. When not performing such a subject-specific measurement, we recommend the use of 1908 ms and 1785 ms for healthy women and men, respectively, or 1841 ms for adults in general. Magn Reson Med 77:2296-2302, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Putamen volume and its clinical and neurological correlates in primary HIV infection.

Little is known about the extent of cortical and subcortical volumetric alterations that may occur within the first year of HIV infection [primary HIV infection (PHI)]. We used structural MRI in this prospective cross-sectional neuroimaging study to determine the extent of volumetric changes in early HIV infection. Cerebrospinal fluid, blood, neuropsychological testing, and structural T1 MRI scans were acquired from 18 HIV and 47 PHI age-matched antiretroviral-naïve male participants. Using FreeSurfer 5.1, volumetric measurements were obtained from the caudate, amygdala, corpus callosum, ventricles, putamen, thalamus, cortical white matter, and total gray matter. Regional volumes were compared groupwise and related to biomarkers in cerebrospinal fluid (viral load, neopterin, and neurofilament light chain), blood (viral load, CD4, and CD8 T-cell count), and neuropsychometric tests (digit-symbol, grooved pegboard, finger-tapping, and timed gait). A trend-level moderate reduction of putamen volume (P = 0.076, adjusted Cohen's d = 0.5 after controlling for age) was observed for PHI compared with HIV-uninfected individuals. Within the PHI group, putamen volume associated with CD4 cell count (P = 0.03), CD4/CD8 ratio (P = 0.045), infection duration (P = 0.009), and worsening psychomotor performance on the digit-symbol (P = 0.028), finger-tapping (P = 0.039), and timed gait (P = 0.009) tests. Our volumetric results suggest that the putamen is preferentially susceptible to early HIV-associated processes. Examining the natural course of early HIV infection longitudinally will allow for mapping of the trajectory of HIV-associated central nervous system changes, enabling creation of improved interventional strategies to potentially stabilize or reverse these observed structural changes.

Empirical model of human blood transverse relaxation at 3 T improves MRI T2 oximetry.

We sought a human blood T2 -oximetery calibration curve over the wide range of hematocrits commonly found in anemic patients applicable with T2 relaxation under spin tagging (TRUST). Blood was drawn from five healthy control subjects. Ninety-three in vitro blood transverse relaxation (T2b ) measurements were performed at 37°C over a broad range of hematocrits (10-55%) and oxygen saturations (14-100%) at 3 Tesla (T). In vivo TRUST was performed on 35 healthy African American control subjects and 11 patients with chronic anemia syndromes. 1/T2 rose linearly with hematocrit (r2 = 0.96), for fully saturated blood. Upon desaturation, 1/T2 rose linearly with the square of the oxygen extraction, (1-Y)2 , and the slope was linearly proportional to hematocrit (r2 = 0.88). The resulting bilinear model between 1/T2 , (1-Y)2 , and hematocrit had a combined r2 of 0.96 and a coefficient of variation of 6.1%. Using the in vivo data, the bilinear model had significantly lower bias and variability than existing calibrations, particularly for low hematocrits. In vivo Bland Altman analysis demonstrated clinically relevant bias that was -6% (absolute saturation) for hematocrits near 30% and rose to + 6% for hematocrits near 45%. This work introduces a robust bilinear calibration model that should be used for MRI oximetry. Magn Reson Med 77:2364-2371, 2017. © 2016 International Society for Magnetic Resonance in Medicine.