Tesla Field Strength Research Articles

Biological variation in cervical spinal cord MRI morphometry in healthy individuals and people with multiple sclerosis.

Conclusions from prior literature regarding the impact of sex, age, and height on spinal cord (SC) MRI morphometrics are conflicting, while the effect of body weight on SC morphometrics has been found to be nonsignificant. The purpose of this case-control study is to assess the associations between cervical SC MRI morphometric parameters and age, sex, height, and weight to establish their potential role as confounding variables in a clinical study of people with multiple sclerosis (MS) compared to a cohort of healthy volunteers. Sixty-nine healthy volunteers and 31 people with MS underwent cervical SC MRI at 3 Tesla field strength. Images were centered at the C3/C4 intervertebral disc and processed using Spinal Cord Toolbox v.4.0.2. Mixed-effects linear regression models were used to evaluate the effects of biological variables and disease status on morphometric parameters. Sex, age, and height had significant effects on cord and gray matter (GM) cross-sectional area (CSA) as well as the GM:cord CSA ratio. There were no significant effects of body weight on morphometric parameters. The effect of MS disease duration on cord CSA in the C4 level was significant when controlling for all other variables. Studies of disease-related changes in SC morphometry should control for sex, age, and height to account for physiological variation.

Sleep-stage-dependent alterations in cerebral oxygen metabolism quantified by magnetic resonance.

A key function of sleep is to provide a regular period of reduced brain metabolism, which is critical for maintenance of healthy brain function. The purpose of this work was to quantify the sleep-stage-dependent changes in brain energetics in terms of cerebral metabolic rate of oxygen (CMRO2 ) as a function of sleep stage using quantitative magnetic resonance imaging (MRI) with concurrent electroencephalography (EEG) during sleep in the scanner. Twenty-two young and older subjects with regular sleep hygiene and Pittsburgh Sleep Quality Index (PSQI) in the normal range were recruited for the study. Cerebral blood flow (CBF) and venous oxygen saturation (SvO2 ) were obtained simultaneously at 3 Tesla field strength and 2.7-s temporal resolution during an 80-min time series using OxFlow, an in-house developed imaging sequence. The method yields whole-brain CMRO2 in absolute physiologic units via Fick's Principle. Nineteen subjects yielded evaluable data free of subject motion artifacts. Among these subjects, 10 achieved slow-wave (N3) sleep, 16 achieved N2 sleep, and 19 achieved N1 sleep while undergoing the MRI protocol during scanning. Mean CMRO2 was 98 ± 7(μmol min-1 )/100 g awake, declining progressively toward deepest sleep stage: 94 ± 10.8 (N1), 91 ± 11.4 (N2), and 76 ± 9.0 μmol min-1 /100 g (N3), with each level differing significantly from the wake state. The technology described is able to quantify cerebral oxygen metabolism in absolute physiologic units along with non-REM sleep stage, indicating brain oxygen consumption to be closely associated with depth of sleep, with deeper sleep stages exhibiting progressively lower CMRO2 levels.

A cross-sectional study to test equivalence of low- versus intermediate-flip angle dynamic susceptibility contrast MRI measures of relative cerebral blood volume in patients with high-grade gliomas at 1.5 Tesla field strength.

1.5 Tesla (1.5T) remain a significant field strength for brain imaging worldwide. Recent computer simulations and clinical studies at 3T MRI have suggested that dynamic susceptibility contrast (DSC) MRI using a 30° flip angle ("low-FA") with model-based leakage correction and no gadolinium-based contrast agent (GBCA) preload provides equivalent relative cerebral blood volume (rCBV) measurements to the reference-standard acquisition using a single-dose GBCA preload with a 60° flip angle ("intermediate-FA") and model-based leakage correction. However, it remains unclear whether this holds true at 1.5T. The purpose of this study was to test this at 1.5T in human high-grade glioma (HGG) patients. This was a single-institution cross-sectional study of patients who had undergone 1.5T MRI for HGG. DSC-MRI consisted of gradient-echo echo-planar imaging (GRE-EPI) with a low-FA without preload (30°/P-); this then subsequently served as a preload for the standard intermediate-FA acquisition (60°/P+). Both normalized (nrCBV) and standardized relative cerebral blood volumes (srCBV) were calculated using model-based leakage correction (C+) with IBNeuro™ software. Whole-enhancing lesion mean and median nrCBV and srCBV from the low- and intermediate-FA methods were compared using the Pearson's, Spearman's and intraclass correlation coefficients (ICC). Twenty-three HGG patients composing a total of 31 scans were analyzed. The Pearson and Spearman correlations and ICCs between the 30°/P-/C+ and 60°/P+/C+ acquisitions demonstrated high correlations for both mean and median nrCBV and srCBV. Our study provides preliminary evidence that for HGG patients at 1.5T MRI, a low FA, no preload DSC-MRI acquisition can be an appealing alternative to the reference standard higher FA acquisition that utilizes a preload.

3 Tesla magnetic resonance imaging in patients with cardiac electronic implantable devices: a single center experience

Abstract Background Cardiac magnetic resonance imaging (MRI), a key method guiding medical diagnosis and therapy, is increasingly performed at 3 Tesla (T) field strength. Growing evidence suggests a relatively safe conductance of 1.5 T MRI in patients with cardiac implantable electronic devices (CIEDs), leading to conditional certification of some CIEDs for MRI. However, data on the safety of MRI imaging at 3 T in patients with CIEDs are scarce. Purpose We analysed the safety of clinically indicated 3 T MRI in patients with “3T MRI-conditional” and “3 T MRI-non-conditional” CIEDs. Methods We performed a retrospective single-center analysis of consecutive patients with CIEDs labelled by the manufacturer as “MRI non-conditional”, “1.5 T MRI-conditional” and “3 T MRI-conditional”. Patients underwent clinically indicated 3 T MRI of different thoracic and non-thoracic body regions from April 2020 to February 2022. Devices were interrogated and programmed appropriately before and after scanning. Statistics included median and interquartile range. Measurements of device and lead function and integrity before and after scanning were assessed. Adverse events included all-cause death, arrhythmias, loss of capture, inappropriate anti-tachycardia therapies, electrical reset and lead or generator failure during or shortly after MRI scan. Results One hundred twenty-eight 3 T MRI scans were performed in 94 patients (mean age 72±16 years, 36.2% female). 3T MRI scans were performed in patients with “non-MRI-conditional” devices (n=9), “1.5 T MRI-conditional” devices (n=22), and “3 T MRI-conditional” devices (n=97). Patients were pacemaker-dependent in 24 MRI scans. After MRI, lead impedance had changed by 100 Ohms or more in seven cases (4 atrial and 3 right ventricular leads). P-wave (−25%) reduction was noted in one, R-wave (−50%) reduction in two cases. Right atrial and ventricular threshold exceeded the limit of 0,5V in one case each only in “3 T MRI-conditional” devices. No clinically relevant adverse events occurred. Conclusion 3 T MRI was safely conducted in patients with “3 T MRI-conditional” and “non-MRI conditional” CIEDs in our single-center study. Pending verification in independent series, our data suggest that clinically indicated 3T MRI scans should not be withheld from patients with cardiac pacemakers or defibrillators. Funding Acknowledgement Type of funding sources: None.

P.74 Using high-field magnetic resonance spectroscopy to measure muscle glycogen in patients with McArdle disease

Glycogen plays a critical role as an energy source in skeletal muscle. McArdle disease is a recessively inherited disorder in which muscle glycogen breakdown is blocked due to myophosphorylase deficiency. The patients suffer from severe exercise intolerance marked by premature fatigue with muscle contractures and episodic rhabdomyolysis. Additionally, some patients show progressive muscular atrophy when they get older, mainly in lumbar paraspinal muscles but not in thigh or calf muscles. The cause of fat replacement in older McArdle patients is unknown but could relate to a higher glycogen accumulation in their muscles. Utilizing the high sensitivity of 13C magnetic resonance spectroscopy at 7 Tesla field strength, we wanted to quantify muscle glycogen in lumbar, thigh and calf muscles in young McArdle patients as well as healthy controls to test the hypothesis of variable glycogen content in muscles of patients with McArdle disease. Preliminary results from 5 patients and 8 controls, show increased muscle glycogen concentration in the calf (4.4 times normal levels, p = 0.002), hamstrings (2.7 times normal levels, p = 0.02) and anterior thigh compartment (3.2 times normal levels, p = 0.01), while there was no difference in the lumbar muscle glycogen content vs. healthy (p = 0.6). No clear pattern of muscle glycogen distribution was seen in neither the McArdle nor the control groups. Our results are in line with previous studies in that we see a 3-5 times increase in glycogen compared to control. Surprisingly, this is not seen in the lumbar muscle group, which is the muscle group most prone to fat replacement with age. Thus, it does not appear that a difference in glycogen concentration between muscles of McArdle patients can explain the fat replacement seen in specific muscles groups of older patients.

Prognostic factors of pelvic MRI at the initial workflow in locally advanced rectal cancer: Focus on extra mural venous invasion and tumour deposits

Tumour deposits (TD) and extramural venous invasion (EMVI) are key anatomopathology prognostic criteria in rectal cancer. According to the 2018 ESGAR recommendations, they should be included in every MRI report. The present study aimed at identifying pelvic MRI survival prognostic factors in locally advanced rectal cancers before neo-adjuvant treatment, with a focus on EMVI and TD (mrEMVI and mrTD). Between 2010 and 2014, we conducted a retrospective study about 69 patients who underwent a pre-operative radiotherapy for a non-metastatic rectal cancer. All MR images were acquired on machines with a 1.5 or 3.0 Tesla field strength and were interpreted in compliance with the 2018 ESGAR recommendations. Out of the 27 patients who were mrEMVI+ (39.1%), MRF was involved in 77.7% of the cases vs. 33.3% for the mrEMVI- tumours. Fifteen (55.5%) out of the 27 mrEMVI+ tumours were mrTD+. This represents 21.7% of our population. mrEMVI/mrTD+ tumours were more RCT resistant, their downstaging happened in 6.7% of cases. In case of tumour downstaging, DFS increased significantly (P=0.02) unlike OS (P=0.2). The present study supports the fact that both mrEMVI and mrTD status are important pelvic MRI prognostic factors. Future studies could focus on relating mrTD tumours status to pathological results to define if post-RCT downstaging of TD has an impact on OS.

Synthetic Haematocrit Formula at 3T Field Strength for the Assessment of Extracellular Volume on Cardiac MRI

The calculation of extracellular volume (ECV) on cardiac MRI relies on T1 relaxation times of the myocardium and cardiac blood pool both pre- and post-contrast administration, as well as measured blood haematocrit levels (ECV=1 – haematocrit x (1/T1myo post – 1/T1myo pre)/(1/T1blood post/1/T1blood pre). The formula to estimate a synthetic haematocrit (synHCT) value is (synHCT=866 x 1/T1blood pre - 0.1232). This formula was validated at 1.5 Tesla (1.5T) field strength, and while it is considered applicable to 3T there is limited data on its accuracy. To evaluate the performance of the synthetic haematocrit (synHCT) formula at 3T field strength in comparison to measured haematocrit (mHCT) when calculating ECV. 40 patients underwent pre- and post-contrast T1 mapping on a Siemens 3T MAGNETOM Skyra machine, with a blood sample drawn immediately prior. Blood pool native T1 values were obtained using an automated blood pool mask (Siemens). There was a linear relationship between mHCT and synHCT with modest correlation (r=0.672). However, there was a significant difference between mean mHCT and synHCT (0.417 vs 0.367 L/L, p<0.00001). Synthetic ECV (synECV) had reasonable correlation with measured ECV (mECV) (r=0.895), although there was still a significant difference between mean mECV and synECV (23.0 vs 25.1%, p<0.00001). The synthetic haematocrit 1.5T formula predicts actual HCT with limited accuracy at 3T. Consequently, the derived synthetic ECV measurements were significantly higher than measured ECV. Further research is needed to derive a more accurate synthetic haematocrit formula for 3 Tesla field strength.

The Value of 3 Tesla Field Strength for Musculoskeletal Magnetic Resonance Imaging.

Musculoskeletal magnetic resonance imaging (MRI) is a careful negotiation between spatial, temporal, and contrast resolution, which builds the foundation for diagnostic performance and value. Many aspects of musculoskeletal MRI can improve the image quality and increase the acquisition speed; however, 3.0-T field strength has the highest impact within the current diagnostic range. In addition to the favorable attributes of 3.0-T field strength translating into high temporal, spatial, and contrast resolution, many 3.0-T MRI systems yield additional gains through high-performance gradients systems and radiofrequency pulse transmission technology, advanced multichannel receiver technology, and high-end surface coils. Compared with 1.5 T, 3.0-T MRI systems yield approximately 2-fold higher signal-to-noise ratios, enabling 4 times faster data acquisition or double the matrix size. Clinically, 3.0-T field strength translates into markedly higher scan efficiency, better image quality, more accurate visualization of small anatomic structures and abnormalities, and the ability to offer high-end applications, such as quantitative MRI and magnetic resonance neurography. Challenges of 3.0-T MRI include higher magnetic susceptibility, chemical shift, dielectric effects, and higher radiofrequency energy deposition, which can be managed successfully. The higher total cost of ownership of 3.0-T MRI systems can be offset by shorter musculoskeletal MRI examinations, higher-quality examinations, and utilization of advanced MRI techniques, which then can achieve higher gains and value than lower field systems. We provide a practice-focused review of the value of 3.0-T field strength for musculoskeletal MRI, practical solutions to challenges, and illustrations of a wide spectrum of gainful clinical applications.

A Spectrum of MRI Findings in the Knee Joint: A Retrospective Study of Selected Population in South-South Nigeria

The knee is a very important joint and injuries affecting it may cause significant disability and discomfort to the patient. Despite a variety of methods available to assess injuries of the knee joint, Magnetic Resonance Imaging (MRI) continues to play a major role. This study evaluated the spectrum of MRI findings in a relatively low resource environment, with limited access to MRI modality. The outcome should justify further investment in MRI services in this locality. The study involves retrospective analysis of MRI reports of 198 clinically symptomatic patients referred for imaging in a Port-Harcourt. All examinations were performed using GE BRIVO MR 235 machine with 0.35 Tesla field strength in a well-coupled standard knee coil. All images were analyzed for normality or otherwise and radiological reports generated by competent radiologists. The most common findings are traumatic in origin, notably cruciate ligament tears (37.37%) and meniscal tears (33.3%) as well as quadriceps tendon tears (3.03%). The medial meniscus and anterior cruciate ligaments were more frequently involved. Furthermore, patients in the 3rd and 4th decade of life were more commonly involved, with a male preponderance. The less common findings of Synovial chondromatosis, cyst-like lesions, tumors and loose bodies, all buttress the importance of routine MRI in atraumatic cases. The spectrum of MRI findings in this study is a reflection of growing interest and confidence in MRI of the diseased knee joint in our environment. The outcome would be a justification for future investments in MRI. Keywords: Magnetic Resonance Imaging, knee injuries, tibial meniscal tears, incidental findings

The effect of extremely low frequency electromagnetic fields following on upregulation of miR-21 and miR-29 in gastric cancer cell line.

Extremely low frequency electromagnetic fields affect miRNAs expression in cancer cell. In this study, electromagnetic fields exposed to low frequency were used to compare miR-21 and miR-29 expressions in a gastric cancer cell line. It has been recently suggested that the low frequency electromagnetic fields probably function as a treatment for cancers. A cultured cell line of gastric cancer was exposed to an electromagnetic radiation system. The cell line was assigned to 4 groups under continuous and discontinuous radiations of 0.25 and 2.5 ml Tesla field strength. Then, the groups were compared with a non-radiation control group. Later, RNA extraction and cDNA synthesis were prepared for miR-21 and miR-29. Real Time PCR method was used to determine how expressions of these two microRNAs differ. Finally, the results were statistically analyzed. The percentage of cell viability in the electromagnetic field radiation experienced a significant decrease compared to that of the control group. In addition, expression of miRNA-21 and miRNA-29 had a significant increase as the strength of the electromagnetic field radiations was on an upward trend. Similarly, the percentage of cell viability saw a significant decline in the upregulation of miRNA-21 and miRNA-29 regardless of radiation types. Findings of this study showed the therapeutic effect of low frequency electromagnetic fields on the gastric cancer cell line. They also indicated that novel biomarkers (miRNA-21 and miRNA-29) could be proposed as potential treatments of gastric cancer, but the results are required to be well established by future studies.

Ultra-high-field sodium MRI as biomarker for tumor extent, grade and IDH mutation status in glioma patients

PurposeThis prospective clinical trial investigated sodium (23Na) MRI at 7 Tesla (T) field strength as biomarker for tumor extent, isocitrate dehydrogenase (IDH) mutation and O6-methylguanine DNA methyltransferase (MGMT) promotor methylation in glioma patients. Methods28 glioma patients underwent 23Na MRI on a 7T scanner (Siemens Healthcare, Erlangen, Germany) parallel to standard 3T MRI before chemoradiation. Areas of Gadolinium-contrast enhancement (gdce), non-enhancing T2-hyperintensity (regarded as edema), necrosis, and normal-appearing white matter (nawm) were segmented on 3T MRI imaging and were co-registered with the 23Na images. The median total 23Na concentrations of all areas were compared by pairwise t-tests. Furthermore, areas of gdce and edema were merged to yield the whole tumor area without necrosis. Subsequently, the difference in median of the 23Na concentration of this whole tumor area was compared between IDH-mutated and IDH wild-type gliomas as well as MGMT methylated and MGMT not-methylated glioblastomas using Whitney-Mann U-tests. All p-values were corrected after the Bonferroni-Holm procedure. ResultsThe 23Na concentration increased successively from nawm to necrotic areas (mean ± sd: nawm = 37.84 ± 5.87 mM, edema = 54.69 ± 10.64 mM, gdce = 61.72 ± 12.95 mM, necrosis = 81.88 ± 17.53 mM) and the concentrations differed statistically significantly between all regarded areas (adjusted p-values for all pairwise comparisons < 0.05). Furthermore, IDH-mutated gliomas showed significantly higher 23Na concentrations than IDH wild-type gliomas (median [interquartile range]: IDH wild-type = 52.37 mM [45.98 – 58.56 mM], IDH mutated = 65.02 mM [58.87–67.05 mM], p = 0.039). Among the glioblastomas, there was a trend towards increased 23Na concentration in MGMT methylated tumors that did not reach statistical significance (median [interquartile range]: MGMT methylated = 57.59 mM [50.70 – 59.17 mM], MGMT not methylated = 48.78 mM [45.88 – 53.91 mM], p = 1.0). Conclusions23Na MRI correlates with the IDH mutation status and could therefore enhance image guidance towards biopsy sites as wells as image-guided surgery and radiotherapy. Furthermore, the successive decrease of 23Na concentration from central necrosis to normal-appearing white matter suggests a correlation with tumor infiltration.

Magnetic brain targeting of naproxen-loaded polymeric micelles: pharmacokinetics and biodistribution study

The blood brain barrier is a major obstacle to the entry of the majority of CNS-active agents. In the present research, the potential of magnetic polymeric micelles (MPMs) for brain-targeting of naproxen was evaluated. The MPMs were made of methoxy poly(ethyleneglycol)-poly (caprolactone) copolymer and super paramagnetic iron oxide nanoparticles (SPIONs). To investigate the impact of particle size on the in vivo biofate of nanoparticles, MPMs with two different sizes were prepared. The prepared magnetic polymeric micelles had diameters of 137 ± 3.5 nm (MPM137) and 242 ± 6.2 nm (MPM242) and their surface charges were about −6.5 and − 4.5 mV, respectively. Pharmacokinetic and biodistribution of nanoparticles were characterized in rats using an external magnet of 0.4 Tesla field strength located on the skull of anesthetized animals. Significant differences in volumes of central as well as peripheral compartments were observed between both MPM formulations and free naproxen solution. After 8 h of administration, the brain concentration of naproxen was shown to be higher in the case of MPM137 in comparison with MPM242 and free drug. The findings revealed that the polymeric magnetic micelles with diameters smaller than 150 nm could be initially considered as a promising carrier to improve therapeutic agent accumulation in the brain for the treatment of CNS diseases.

Facial nerve stimulation in normal pigs and healthy human volunteers: transitional development of a medical device for the emergency treatment of ischemic stroke

BackgroundMagnetic stimulation of the facial nerve has been tested in preclinical studies as a new, non-invasive emergency treatment of ischemic stroke that acts by increasing cerebral blood flow (CBF). The objective of the studies reported herein was to identify minimal stimulation parameters that increase CBF in large animals and then test those stimulation parameters in healthy volunteers for safety, tolerability, and effectiveness at increasing CBF. This translational research is necessary preparation for clinical studies in ischemic stroke patients.MethodsInitial experiments in anesthetized Yorkshire pigs were undertaken in order to identify the lowest stimulus power and duration that increase CBF. A full 3 × 3 factorial design was used to evaluate magnetic stimulation of the facial nerve at various stimulation powers (1.3, 1.6, and 1.9 Tesla field strength at coil surface) and for various durations (2, 3.5, and 5 min). CBF was measured with contrast MRI perfusion imaging and the internal carotid arteries were assessed with MR angiography. Magnetic facial nerve stimulation with parameters identified in the pig study was then applied to 35 healthy volunteers. Safety was assessed with adverse event reports and by medical examination. Tolerability was defined as each volunteer’s ability to withstand at least 2 min of stimulation. Volunteers could determine the maximum power of stimulation they received during a ramp-up period.ResultsIn pigs, unilateral facial nerve stimulation increased CBF by as much as 77% over pre-stimulation baseline when administered across a range of 1.3–1.9 Tesla power and for 2- to 5-min duration. No clear dose–response relationship could be observed across this range, but lower powers and durations than these were markedly less effective. The effect of a single stimulation lasted 90 min. A second stimulation delivered 100 min after the first stimulation sustained the increased CBF without evidence of tachyphylaxis. In human, bilateral facial nerve stimulation caused only non-serious adverse events that were limited to the 2-min stimulation period. Tolerability was greatly improved by gentle encouragement from the study staff, which enabled most volunteers to tolerate 1.6–1.8 Tesla of stimulation power. CBF measures taken approximately 10 min after stimulation demonstrated on average a 32 ± 6% increase in CBF, with ≥ 25% increases in CBF occurring in 10 of the 31 volunteers who had adequate CBF measurements.ConclusionsThe minimal effective stimulation parameters defined by increased CBF, as identified in the pig study, translated into safe, tolerable, and effective stimulation of healthy volunteers. These results support the future development and evaluation of non-invasive facial nerve stimulation for the emergency treatment of ischemic stroke.Trial Registration retrospectively registered with clinicaltrials.gov NRV_P1_01_15 on June 6, 2017

Erratum: Cardiac Magnetic Resonance with a Conditional Pacemaker at Three Tesla Field Strength

Erratum: Cardiac Magnetic Resonance with a Conditional Pacemaker at Three Tesla Field Strength

Cardiac Magnetic Resonance with a Conditional Pacemaker at Three Tesla Field Strength

Cardiac Magnetic Resonance with a Conditional Pacemaker at Three Tesla Field Strength

Seven-Tesla Magnetization Transfer Imaging to Detect Multiple Sclerosis White Matter Lesions.

Fluid-attenuated inversion recovery (FLAIR) imaging at 3 Tesla (T) field strength is the most sensitive modality for detecting white matter lesions in multiple sclerosis. While 7T FLAIR is effective in detecting cortical lesions, it has not been fully optimized for visualization of white matter lesions and thus has not been used for delineating lesions in quantitative magnetic resonance imaging (MRI) studies of the normal appearing white matter in multiple sclerosis. Therefore, we aimed to evaluate the sensitivity of 7T magnetization-transfer-weighted (MTw ) images in the detection of white matter lesions compared with 3T-FLAIR. Fifteen patients with clinically isolated syndrome, 6 with multiple sclerosis, and 10 healthy participants were scanned with 7T 3-dimensional (D) MTw and 3T-2D-FLAIR sequences on the same day. White matter lesions visible on either sequence were delineated. Of 662 lesions identified on 3T-2D-FLAIR images, 652 were detected on 7T-3D-MTw images (sensitivity, 98%; 95% confidence interval, 97% to 99%). The Spearman correlation coefficient between lesion loads estimated by the two sequences was .910. The intrarater and interrater reliability for 7T-3D-MTw images was good with an intraclass correlation coefficient (ICC) of 98.4% and 81.8%, which is similar to that for 3T-2D-FLAIR images (ICC 96.1% and 96.7%). Seven-Tesla MTw sequences detected most of the white matter lesions identified by FLAIR at 3T. This suggests that 7T-MTw imaging is a robust alternative for detecting demyelinating lesions in addition to 3T-FLAIR. Future studies need to compare the roles of optimized 7T-FLAIR and of 7T-MTw imaging.

Proton MR spectroscopic imaging of human glioblastomas at 1.5 Tesla.

In this study we evaluated clinical feasibility of proton magnetic resonance spectroscopy metabolite mapping (1H MRSI) by using 1.5 Tesla MR-scanner in 10 patients with high-grade glioblastoma. In vivo 1H MRSI performed with a relatively short scan time of 20 minutes enabled to obtain comprehensive information about metabolic changes in glioblastoma and adjacent tissues namely in the peritumoral edema, in the middle and solid part of the tumor, and in the normal-appearing brain tissue. Spectroscopically it was possible to identify initiation of neuronal cell death in the solid tumorous tissue via decreased N-acetyl-aspartate to creatine ratio (↓ tNAA/tCr) and expanding carcinogenesis reflected in elevated choline ratios (↑ tCho/tCr and tCho/tNAA). We showed also the central necrosis of glioblastoma accompanied by the tissue hypoxia, which were apparent as increased lactate and lipids ratios (↑ Lac/tCr and lip/Lac). Metabolic changes were noticeable also in the peritumoral area, showing the glioblastoma infiltration into the surrounding tissues. In intracranial tumors, 1H MRSI performed on 1.5 Tesla field strength was sufficient to provide information about the stage of carcinogenesis, tumor expansion or necrotization and thus it could be considered as a useful diagnostic tool in oncology.

Assessment of Cervical Cancer with a Parameter-Free Intravoxel Incoherent Motion Imaging Algorithm.

ObjectiveTo evaluate the feasibility of a parameter-free intravoxel incoherent motion (IVIM) approach in cervical cancer, to assess the optimal b-value threshold, and to preliminarily examine differences in the derived perfusion and diffusion parameters for different histological cancer types.Materials and MethodsAfter Institutional Review Board approval, 19 female patients (mean age, 54 years; age range, 37–78 years) gave consent and were enrolled in this prospective magnetic resonance imaging study. Clinical staging and biopsy results were obtained. Echo-planar diffusion weighted sequences at 13 b-values were acquired at 3 tesla field strength. Single-sliced region-of-interest IVIM analysis with adaptive b-value thresholds was applied to each tumor, yielding the optimal fit and the optimal parameters for pseudodiffusion (D*), perfusion fraction (Fp) and diffusion coefficient (D). Monoexponential apparent diffusion coefficient (ADC) was calculated for comparison with D.ResultsBiopsy revealed squamous cell carcinoma in 10 patients and adenocarcinoma in 9. The b-value threshold (median [interquartile range]) depended on the histological type and was 35 (22.5–50) s/mm2 in squamous cell carcinoma and 150 (100–150) s/mm2 in adenocarcinoma (p < 0.05). Comparing squamous cell vs. adenocarcinoma, D* (45.1 [25.1–60.4] × 10−3 mm2/s vs. 12.4 [10.5–21.2] × 10−3 mm2/s) and Fp (7.5% [7.0–9.0%] vs. 9.9% [9.0–11.4%]) differed significantly between the subtypes (p < 0.02), whereas D did not (0.89 [0.75–0.94] × 10−3 mm2/s vs. 0.90 [0.82–0.97] × 10−3 mm2/s, p = 0.27). The residuals did not differ (0.74 [0.60–0.92] vs. 0.94 [0.67–1.01], p = 0.32). The ADC systematically underestimated the magnitude of diffusion restriction compared to D (p < 0.001).ConclusionThe parameter-free IVIM approach is feasible in cervical cancer. The b-value threshold and perfusion-related parameters depend on the tumor histology type.

Evaluation of an fMRI USPIO-based assay in healthy human volunteers

To present the testretest and contrast dose effect results of cerebral blood volume (CBV) functional MRI (fMRI) in healthy human volunteers using ferumoxytol (Feraheme), an ultrasmall-superparamagnetic iron oxide (USPIO) nanoparticle. This was an open-label, two-period, fixed-sequence study in healthy young volunteers. In eight subjects, using a 3 Tesla field strength system, blood oxygen level dependent (BOLD) and CBV fMRI were acquired in response to a visual black-and-white checkboard stimulation paradigm using an escalating ferumoxytol dose design (250, 350, and 510 mg iron). Multiple outcome measures were analyzed including absolute percent signal change (|PSC|, primary endpoint), its contrast-to-noise ratio (CNR) and corresponding z-score, percent CBV change (ΔCBV) and respective CNR, concentration of Fe, and baseline CBV. The |PSC| in the visual cortex increased with ferumoxytol dose and was up to 3 × higher than BOLD fMRI. Test-retest reliability was comparable for BOLD and CBV fMRI. Intraclass correlation coefficients (ICCs) for |PSC| were 0.3 (one-sided 95% lower confidence limit = 0.00), 0.81 (0.47), 0.48 (0.00), and 0.3 (0.00) for BOLD and the 250-, 350-, and 510-mg doses of ferumoxytol, respectively. For ΔCBV, ICCs were 0.77 (0.37), 0.48 (0.00), and 0.49 (0.00) for 250 mg, 350 mg, and 510 mg, respectively. This work demonstrates that CBV fMRI techniques and endpoints are dose dependent, robust and have good test-retest repeatability. It also confirms previous findings that USPIO enhances sensitivity of fMRI stimulus-response endpoints. 1 J. MAGN. RESON. IMAGING 2017;46:124-133.

Diagnostic accuracy of 3T conventional shoulder MRI in the detection of the long head of the biceps tendon tears associated with rotator cuff tendon tears.

To evaluate the diagnostic performance (DP) of 3T (3 Tesla field strength) conventional shoulder magnetic resonance imaging (MRI) in detecting the long head of the biceps tendon (LHBT) tears in association with rotator cuff tendon tears. This study included 80 consecutive patients who underwent arthroscopic surgery for rotator cuff tendon tears. Two radiologists independently evaluated the preoperative 3T shoulder MRI for the presence of LHBT tears. The DP of MRI was evaluated using the results of arthroscopy as the reference standard. We also evaluated the DP of several MR signs of LHBT in detection of partial LHBT tears. Arthroscopic examination revealed 35 partial and 5 complete tears. According to the results of evaluation by reviewers 1 and 2, shoulder MRI exhibited sensitivities of 77.14 and 80% and specificities of 71.11 and 73.33% in detection of partial LHBT tears and sensitivities of 80 and 100% and a specificity of 100% (both) in detection of complete LHBT tears. In detecting partial LHBT tears, increased T2 signal intensity of the LHBT exhibited high sensitivities (reviewers 1 and 2; 82.85 and 80%, respectively) and the presence of intratendinous defects or C-signs exhibited the highest specificities (reviewers 1 and 2; 95.55 and 93.33%, respectively), followed by abnormalities in shape and outer margins of the LHBT (reviewers 1 and 2; 91.11 and 82%; 91.11 and 86.66%, respectively). Non-contrast-enhanced 3T shoulder MRI is potentially highly accurate in detection of complete LHBT tears, but moderately accurate in detection of partial LHBT tears.