Noncontrast Magnetic Resonance Research Articles

Automating aortic cross-sectional measurement of 3D aorta models.

Aortic dissection carries a mortality as high as 50%, but surgical palliation is also fraught with morbidity risks of stroke or paralysis. As such, a significant focus of medical decision making is on longitudinal aortic diameters. We hypothesize that three-dimensional (3D) modeling affords a more efficient methodology toward automated longitudinal aortic measurement. The first step is to automate the measurement of manually segmented 3D models of the aorta. We developed and validated an algorithm to analyze a 3D segmented aorta and output the maximum dimension of minimum cross-sectional areas in a stepwise progression from the diaphragm to the aortic root. Accordingly, the goal is to assess the diagnostic validity of the 3D modeling measurement as a substitute for existing 2D measurements. From January 2021 to June 2022, 66 3D non-contrast steady-state free precession magnetic resonance images of aortic pathology with clinical aortic measurements were identified; 3D aorta models were manually segmented. A novel mathematical algorithm was applied to each model to generate maximal aortic diameters from the diaphragm to the root, which were then correlated to clinical measurements. With a 76% success rate, we analyzed the resulting 50 3D aortic models utilizing the automated measurement tool. There was an excellent correlation between the automated measurement and the clinical measurement. The intra-class correlation coefficient and -value for each of the nine measured locations of the aorta were as follows: sinus of valsalva, 0.99, ; sino-tubular junction, 0.89, ; ascending aorta, 0.97, ; brachiocephalic artery, 0.96, ; transverse segment 1, 0.89, ; transverse segment 2, 0.93, ; isthmus region, 0.92, ; descending aorta, 0.96, ; and aorta at diaphragm, 0.3, . Automating diagnostic measurements that appease clinical confidence is a critical first step in a fully automated process. This tool demonstrates excellent correlation between measurements derived from manually segmented 3D models and the clinical measurements, laying the foundation for transitioning analytic methodologies from 2D to 3D.

Diagnostic yield of computed tomography angiography in patients presenting with spontaneous intracerebral hemorrhage.

Hypertension and cerebral amyloid angiopathy are the most common causes of spontaneous intracerebral hemorrhage (ICH); however, these conditions do not imply macrovascular pathology. Still, computed tomography (CT) angiography (CTA) is often performed in the acute phase in patients with ICH. To assess the diagnostic yield of CTA in the detection of secondary etiology in consecutive patients with spontaneous ICH. We performed a retrospective analysis of data from a prospective single-center cohort study of 203 patients presenting with spontaneous ICH admitted to a comprehensive stroke center over a two-year period (15 October 2016 to 15 October 2018). The underlying vascular pathology was assessed using CTA. CTA was performed in addition to non-contrast CT and/or magnetic resonance imaging (MRI). Vascular pathology was found in 11 of 203 (5.4%) patients and included arteriovenous malformations (n=4), aneurysms (n=4), vasospasms (n=1), cerebral venous thrombosis (n=1), and other vascular malformations (n=1). In eight cases, the finding was deemed symptomatic. Patients with vascular pathology on CTA more often had lobar located hemorrhages (63.6% vs. 36.4%, P = 0.049). Numerically, patients with vascular pathology were younger, had smaller hematoma volumes, and lower mortality. Underlying macrovascular pathology was detected on CTA in only approximately 1 of 20 consecutive patients with ICH. The patients with vascular pathology more often had a hemorrhage with a lobar location and young age and the present study is supportive of a risk-based stratification approach in performing CTA.

Evaluating the diagnostic performance of non-contrast magnetic resonance angiography sequences in the pre-procedural comprehensive analysis of direct carotid cavernous fistula.

Endovascular treatment of direct carotid cavernous fistula (DCCF) requires invasive diagnostic cerebral angiography for diagnosis and planning; however, a less invasive modality like magnetic resonance angiography (MRA) can be useful, especially in high-risk cases. This single-centre study evaluated a newer MR angiography (MRA) sequence, silent MRA and the traditional time of flight (TOF) MRA for pre-procedural treatment planning of DCCF. All consecutive DCCF patients who underwent TOF, silent MRA and diagnostic cerebral angiography were included in the study. Angiographic features like rent size, location, draining veins and collateral communicating arteries were analysed and compared between the two MRA sequences, with digital subtraction angiography (DSA) as the gold standard. Fifteen patients were included in the study. TOF MRA exhibited better sensitivity (76.9% vs 69.2%) in identifying the rent location, correctly pinpointing the location in 93.3% compared to 73.3% with silent MRA. Both MRA sequences showed good agreement with DSA for primary sac and rent size. TOF MRA correctly identified 86.2% of 210 total venous structures compared to 96% by silent MRA. Silent MRA demonstrated higher sensitivity (90% vs 76%) and accuracy (87.69 vs 94.36) in visualisation of involved veins compared to TOF MRA. Arterial characteristics of DCCF like rent location and rent size were better assessed by TOF MRA. Although both MRA identified venous features, silent MRA correlated better with DSA irrespective of the size and proximity to the site of the fistula. Combining both sequences can evaluate various angioarchitectural features of DCCF useful for therapeutic planning.

S1 vertebral bone quality score independently predicts pedicle screw loosening following surgery in patients with adult degenerative scoliosis

BACKGROUND CONTEXTMRI-based vertebral bone quality (VBQ) score is an effective predictor of pedicle screw loosening after lumbar fusion surgery and has been recognized as a valuable tool for assessing preoperative bone quality. Due to the lateral curvature of lumbar spine of degenerative scoliosis, accurate measurement of VBQ score by conventional measurement methods that capture MRI signal intensity at L1–4 may be limited under certain conditions. To this end, a new simplified S1 VBQ score method has been proposed, which is comparable to the previous L1–4 VBQ score or S1 Hounsfield unit (HU) value, and has high accuracy and reliability. PURPOSETo evaluate the predictive value of MRI-based S1 VBQ score for pedicle screw loosening following surgery for adult degenerative scoliosis (ADS). STUDY DESIGN/SETTINGRetrospective single-center cohort. PATIENT SAMPLEWe reviewed 92 patients who underwent posterior lumbar interbody fusion (PLIF) with pedicle screw fixation for ADS between January 2017 and January 2020. OUTCOME MEASURESAssociation between S1 VBQ score and pedicle screw loosening following surgery for ADS. METHODSWe retrospectively reviewed the records of all patients who performed PLIF between January 2017 and January 2020. The clear zone around pedicle screws≥1 mm can be identified as screw loosening. The S1 VBQ score is calculated from the S1 central-based non-contrast T1-weighted magnetic resonance imaging (MRI). The signal intensity (SI) of the cerebrospinal fluid (CSF) was then measured using ROI placed at the L3 level to normalize the results. Multivariate logistic regression analysis was performed to identify independent risk factors for screw loosening. Then, constructed a receiver operating characteristic (ROC) curve and determined the threshold (cut-off) of VBQ score with high sensitivity and specificity based on Youden Index. RESULTSA total of 92 patients were included, including 34 males and 58 females. The mean age of the patients was 61.23±1.23 years old. At 1-year follow-up, the screw loosening rate was 56.5% (52/92). The age and levels of fixation were higher in the loosening group than in the non-loosening group (p=.036, p=.025). Patients in the loosening group had a greater VBQ score compared to patients in the non-loosening group (3.31±0.41 vs 3.01±0.28, p=.001). Multivariate logistic regression analysis showed that advanced age (OR, 1.090; 95% CI 1.005–1.183; p=.039) and higher VBQ score (OR, 5.778; 95% CI 2.889–16.177; p=.001) were independent risk factors for screw loosening. In addition, the ROC curve were created to assess the role of VBQ score as predictors of screw loosening with a diagnostic accuracy of 74.6% (95% CI 64.2%–85.1%).The most suitable threshold for the VBQ score as determined by the Youden Index was 3.175 (sensitivity: 76.0%, specificity: 83.3%). CONCLUSIONSHigher S1 VBQ score was significantly associated with pedicle screw loosening following surgery for ADS. The S1 VBQ score can be used as an effective preoperative predictor, which has the potential clinical application.

Evaluation of fractional flow reserve and atherosclerotic plaque characteristics on coronary non-contrast T1-weighted magnetic resonance imaging

Background and aimsThe relationship between high-risk coronary plaque characteristics regardless of the severity of lesion stenosis and myocardial ischemia remains unsettled. High-intensity plaques (HIPs) on non-contrast T1-weighted magnetic resonance imaging (T1WI) have been characterized as high-risk coronary plaques. We sought to elucidate whether the presence of coronary HIPs on T1WI influences fractional flow reserve (FFR) in the distal segment of the vessel. MethodsWe retrospectively analyzed 281 vessels in 231 patients with chronic coronary syndrome who underwent invasive FFR measurement and coronary T1WI using a multicenter registry. The plaque-to-myocardial signal intensity ratio (PMR) of the most stenotic lesion was evaluated; a coronary plaque with PMR ≥1.4 was defined as a HIP. ResultsThe median PMR of coronary plaques on T1WI in vessels with FFR ≤0.80 was significantly higher than that of plaques with FFR >0.80 (1.17 [interquartile range (IQR): 0.99–1.44] vs. 0.97 [IQR: 0.85–1.09]; p < 0.001). Multivariable analysis showed that an increase in PMR of the most stenotic segment was associated with lower FFR (beta-coefficient, −0.050; p < 0.001). The presence of coronary HIPs was an independent predictor of FFR ≤0.80 (odds ratio (OR), 6.18; 95% confidence interval (CI), 1.93–19.77; p = 0.002). Even after adjusting for plaque composition characteristics based on computed tomography angiography, the presence of coronary HIPs was an independent predictor of FFR ≤0.80 (OR, 4.48; 95% CI, 1.19–16.80; p = 0.026). ConclusionsCoronary plaques with high PMR are associated with low FFR in the corresponding vessel, indicating that plaque morphology might influence myocardial ischemia severity.

Progression of fluid infiltration on non-contrast magnetic resonance imaging in breast cancer-related lymphedema: A comparative analysis with indocyanine green lymphography

BackgroundNon-contrast magnetic resonance imaging (NMRI) has been reported as valuable for the assessment of lymphedema. However, the correlation between NMRI findings and indocyanine green lymphography (ICG-L) findings remains elusive. MethodsThis single-center retrospective study included 26 patients diagnosed with breast cancer-related lymphedema. We examined the prevalence of fluid infiltration in eight regions of the upper extremity, the type of fluid distribution, and the dominant segment of edema on NMRI in comparison to the ICG-L stage. Statistical analysis was performed using the Cochran–Armitage trend test, Spearman’s rank correlation test, and Fisher’s exact test. ResultsThe regional fluid infiltration significantly increased with the progression of the ICG-L stage (hand, forearm, elbow, and upper arm: p = 0.003, <0.001, <0.001, and <0.001, respectively). The fluid distribution significantly advanced with the progression of the ICG-L stage as follows (rs = 0.80; p < 0.001): no edema in ICG-L stage 0, edema in either the hand or elbow in ICG-L stage I, edemas in both the elbow and hand in ICG-L stage II, three segmental edemas centered on the forearm or elbow in ICG-L stage III, and edema encompassing the entire upper limb in ICG-L stage IV-V. Additionally, the dominant segment of edema tended to shift from the hand to the elbow and further to the forearm as the ICG-L stage progressed (p < 0.001). ConclusionsFluid infiltration observed on NMRI exhibited distinct patterns with the progression of the ICG-L stage. We believe that anatomical information regarding fluid distribution would potentially contribute to optimizing surgical efficacy.

Atrial and ventricular strain using cardiovascular magnetic resonance in the prediction of outcomes of pericarditis patients: a pilot study.

Our study aimed to explore with cardiovascular magnetic resonance (CMR) the impact of left atrial (LA) and left ventricular (LV) myocardial strain in patients with acute pericarditis and to investigate their possible prognostic significance in adverse outcomes. This retrospective study performed CMR scans in 36 consecutive patients with acute pericarditis (24 males, age 52 [23-52]). The primary endpoint was the combination of recurrent pericarditis, constrictive pericarditis, and surgery for pericardial diseases defined as pericardial events. Atrial and ventricular strain function were performed on conventional cine SSFP sequences. After a median follow-up time of 16months (interquartile range [13-24]), 12 patients with acute pericarditis reached the primary endpoint. In multivariable Cox regression analysis, LA reservoir and LA conduit strain parameters were all independent determinants of adverse pericardial diseases. Conversely, LV myocardial strain parameters did not remain an independent predictor of outcome. With receiving operating characteristics curve analysis, LA conduit and reservoir strain showed excellent predictive performance (area under the curve of 0.914 and 0.895, respectively) for outcome prediction at 12months. LA reservoir and conduit mechanisms on CMR are independently associated with a higher risk of adverse pericardial events. Including atrial strain parameters in the management of acute pericarditis may improve risk stratification. Atrial strain could be a suitable non-invasive and non-contrast cardiovascular magnetic resonance parameter for predicting adverse pericardial complications in patients with acute pericarditis. • Myocardial strain is a well-validated CMR parameter for risk stratification in cardiovascular diseases. • LA reservoir and conduit functions are significantly associated with adverse pericardial events. • Atrial strain may serve as an additional non-contrast CMR parameter for stratifying patients with acute pericarditis.

Cine-cardiac magnetic resonance to distinguish between ischemic and non-ischemic cardiomyopathies: a machine learning approach.

This work aimed to derive a machine learning (ML) model for the differentiation between ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM) on non-contrast cardiovascular magnetic resonance (CMR). This retrospective study evaluated CMR scans of 107 consecutive patients (49 ICM, 58 NICM), including atrial and ventricular strain parameters. We used these data to compare an explainable tree-based gradient boosting additive model with four traditional ML models for the differentiation of ICM and NICM. The models were trained and internally validated with repeated cross-validation according to discrimination and calibration. Furthermore, we examined important variables for distinguishing between ICM and NICM. A total of 107 patients and 38 variables were available for the analysis. Of those, 49 were ICM (34 males, mean age 60 ± 9years) and 58 patients were NICM (38 males, mean age 56 ± 19years). After 10 repetitions of the tenfold cross-validation, the proposed model achieved the highest area under curve (0.82, 95% CI [0.47-1.00]) and lowest Brier score (0.19, 95% CI [0.13-0.27]), showing competitive diagnostic accuracy and calibration. At the Youden's index, sensitivity was 0.72 (95% CI [0.68-0.76]), the highest of all. Analysis of predictions revealed that both atrial and ventricular strain CMR parameters were important for the identification of ICM patients. The current study demonstrated that using a ML model, multi chamber myocardial strain, and function on non-contrast CMR parameters enables the discrimination between ICM and NICM with competitive diagnostic accuracy. A machine learning model based on non-contrast cardiovascular magnetic resonance parameters may discriminate between ischemic and non-ischemic cardiomyopathy enabling wider access to cardiovascular magnetic resonance examinations with lower costs and faster imaging acquisition. • The exponential growth in cardiovascular magnetic resonance examinations may require faster and more cost-effective protocols. • Artificial intelligence models can be utilized to distinguish between ischemic and non-ischemic etiologies. • Machine learning using non-contrast CMR parameters can effectively distinguish between ischemic and non-ischemic cardiomyopathies.

Magnetic Resonance Imaging in Breast Cancer Tissue In Vitro after PDT Therapy.

Photodynamic therapy (PDT) is increasingly used in modern medicine. It has found application in the treatment of breast cancer. The most common cancer among women is breast cancer. We collected cancer cells from the breast from the material received after surgery. We focused on tumors that were larger than 10 mm in size. Breast cancer tissues for this quantitative non-contrast magnetic resonance imaging (MRI) study could be seen macroscopically. The current study aimed to present findings on quantitative non-contrast MRI of breast cancer cells post-PDT through the evaluation of relaxation times. The aim of this work was to use and optimize a 1.5 T MRI system. MRI tests were performed using a clinical scanner, namely the OPTIMA MR360 manufactured by General Electric HealthCare. The work included analysis of T1 and T2 relaxation times. This analysis was performed using the MATLAB package (produced by MathWorks). The created application is based on medical MRI images saved in the DICOM3.0 standard. T1 and T2 measurements were subjected to the Shapiro-Wilk test, which showed that both samples belonged to a normal distribution, so a parametric t-test for dependent samples was used to test for between-sample variability. The study included 30 sections tested in 2 stages, with consistent technical parameters. For T1 measurements, 12 scans were performed with varying repetition times (TR) and a constant echo time (TE) of 3 ms. For T2 measurements, 12 scans were performed with a fixed repetition time of 10,000 ms and varying echo times. After treating samples with PpIX disodium salt and bubbling with pure oxygen, PDT irradiation was applied. The cell relaxation time after therapy was significantly shorter than the cell relaxation time before PDT. The cells were exposed to PpIX disodium salt as the administered pharmacological substance. The study showed that the therapy significantly affected tumor cells, which was confirmed by a significant reduction in tumor cell relaxation time on the MRI results.

Early detection of myocardial involvement by non-contrast T1ρ mapping of cardiac magnetic resonance in type 2 diabetes mellitus.

This study aims to determine the effectiveness of T1ρ in detecting myocardial fibrosis in type 2 diabetes mellitus (T2DM) patients by comparing with native T1 and extracellular volume (ECV) fraction. T2DM patients (n = 35) and healthy controls (n = 30) underwent cardiac magnetic resonance. ECV, T1ρ, native T1, and global longitudinal strain (GLS) values were assessed. Diagnostic performance was analyzed using receiver operating curves. The global ECV and T1ρ of T2DM group (ECV = 32.1 ± 3.2%, T1ρ = 51.6 ± 3.8 msec) were significantly higher than those of controls (ECV = 26.2 ± 1.6%, T1ρ = 46.8 ± 2.0 msec) (all P < 0.001), whether there was no significant difference in native T1 between T2DM and controls (P = 0.264). The GLS decreased significantly in T2DM patients compared with controls (-16.5 ± 2.4% vs. -18.3 ± 2.6%, P = 0.015). The T1ρ and native T1 were associated with ECV (Pearson's r = 0.50 and 0.25, respectively, both P < 0.001); the native T1, T1ρ, and ECV were associated with hemoglobin A1c (Pearson's r = 0.41, 0.52, and 0.61, respectively, all P < 0.05); and the ECV was associated with diabetes duration (Pearson's r = 0.41, P = 0.016). The AUC of ECV, T1ρ, GLS, and native T1 were 0.869, 0.810, 0.659, and 0.524, respectively. In T2DM patients, T1ρ may be a new non-contrast cardiac magnetic resonance technique for identifying myocardial diffuse fibrosis, and T1ρ may be more sensitive than native T1 in the detection of myocardial diffuse fibrosis.

Non-Contrast Magnetic Resonance Imaging of Isolated Superior Mesenteric Artery Dissection.

Non-Contrast Magnetic Resonance Imaging of Isolated Superior Mesenteric Artery Dissection.

Can non-contrast magnetic resonance imaging replace contrast-enhanced computerized tomography in the local staging of pediatric renal tumors?

BackgroundRenal tumors account for approximately 6–7% of the total incidence of pediatric cancers. Wilms tumor (WT) is the most common renal malignancy observed in the pediatric population under 5 years old. Computed tomography (CT) is used for staging of the renal tumors. Magnetic resonance imaging (MRI) offers enhanced soft tissue resolution and provides more comprehensive insights into tumor extension through the capsule, including tumor infiltration into the renal vein or IVC. MRI is a noninvasive imaging modality that does not involve any radiation hazards, making it safe for children. In addition, MRI can be performed without the administration of contrast agents in patients with impaired renal function. Therefore, MRI plays a vital role in screening, staging, preoperative evaluation, and follow-up. Diffusion-weighted imaging (DWI) is a functional tool that aids in locating the most receptive tumoral region to guide confirmatory biopsies. In this study, we aim to evaluate the potential value of non-contrast MRI in staging pediatric renal tumors compared to contrast-enhanced CT.ResultsThis study included 50 patients presented with renal mass, with ages ranging from 1 to 8 years and a mean age of 4.27 ± 1.27 (mean ± SD). The final diagnosis was Wilm’s tumor at 86%, clear cell sarcoma at 4%, rhabdoid tumor at 4%, rhabdomyosarcoma at 2%, and nephroblastomatosis with no malignant transformation at 4%. CT accurately diagnosed stages 4 and 5 in agreement with pathological findings while upstaging the other cases, with a CT sensitivity of 90.91%, specificity of 82.35%, PPV of 92%, and NPV of 84%. MRI is superior to CT in stages 1 and 3, accurately diagnosing stages 2, 4, and 5, with a sensitivity of 93.30%, specificity of 95.65%, PPV of 95%, and NPV of 97%.ConclusionsNon-contrast MRI could be considered the optimal radiation-free imaging modality in staging pediatric renal tumors mainly Wilm’s tumor as it offers high sensitivity and specificity of capsular and vascular infiltration, compared to contrast-enhanced CT especially in cases with impaired renal functions.

Diagnostic accuracy of non-contrast MRI in frozen shoulder.

Despite being the most used exam today, few studies have evaluated the accuracy of findings on non-contrast magnetic resonance imaging (MRI). The primary objective of the study was to evaluate the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of non-contrast MRI findings in frozen shoulder, isolated and in combination. The secondary objectives were to define the interobserver and intraobserver agreement of the assessments and the odds ratio for frozen shoulder because of the various findings of MRI. A retrospective diagnostic accuracy study comparing non-contrast MRI findings between the frozen shoulder group and the control group. Sensitivity, specificity, positive and negative predictive value, accuracy, odds ratio, interobserver and intraobserver agreement were calculated for each finding and their possible associations. The hyperintensity on capsule in the axillary recess presented 84% sensitivity, 94% specificity, and 89% accuracy. The obliteration of the subcoracoid fat triangle in the rotator interval had sensitivity 34%, specificity 82% and accuracy 58%. For coracohumeral ligament thickness ≥ 2mm had specificity 66%, 48% specificity and 57% accuracy. Capsule thickness in the axillary recess ≥ 4mm resulted in 54% sensitivity, 82% specificity, and 68% accuracy. Regarding interobserver agreement, only the posteroinferior and posterosuperior quadrants showed moderate results, and all the others showed strong reliability. The odds ratio for hyperintensity in the axillary recess was 82.3 for frozen shoulder. The association of these findings increased specificity (95%). The accuracy of non-contrast magnetic resonance imaging is high for diagnosing frozen shoulder, especially when evaluating the hyperintensity of the axillary recess. The exam has high reliability and reproducibility. The presence of an association of signs increases the specificity of the test. Level III, study of diagnostic test.

Three-dimensional non-contrast magnetic resonance lymphography severity stage for upper extremity lymphedema

PurposesNon-contrast magnetic resonance lymphography (NMRL) has recently shown the capability of evaluating anatomical fluid distribution in upper extremity lymphedema (UEL). However, there is still a lack of knowledge about the correlation between the characteristic three-dimensional (3D) NMRL findings and the indocyanine green lymphography (ICG-L) findings. Our goal was to clarify the relationship between the 3D NMRL findings and the ICG-L findings. MethodsMedical charts of patients with secondary UEL who underwent NMRL and ICG-L between January 2018 to October 2021 were reviewed. The upper extremities were divided into 6 regions; the hand, elbow, and the radial and ulnar aspects of the forearm and the upper arm. We investigated the prevalence of characteristic 3D NMRL patterns (Mist/Spray/Inky) in each region based on the ICG-L stage. We also examined the association between the 3D NMRL stage which we proposed and the ICG-L stage, and other clinical factors. ResultsA total of 150 regions of 25 patients with upper extremities lymphedema were enrolled in the study. All of the characteristic patterns increased significantly as the ICG-L stage advanced (p < 0.001, < 0.001, and < 0.001, respectively). The predominant NMRL patterns changed significantly from the Early pattern (Mist pattern) to the Advanced pattern (Inky/Spray pattern) as the ICG-L stage progressed (p < 0.001). The higher Stage of 3D NMRL was significantly associated with the progression of the ICG-L stage (rs = 0.80, p < 0.001). ConclusionsCharacteristic 3D NMRL patterns and the 3D NMRL Stage had a significant relationship with the ICG-L stage and other clinical parameters. This information may be an efficient tool for a more precise and objective evaluation of various treatments for UEL patients.

A Non-Contrast Multi-Parametric MRI Biomarker for Assessment of MR-Guided Focused Ultrasound Thermal Therapies.

We present the development of a non-contrast multi-parametric magnetic resonance (MPMR) imaging biomarker to assess treatment outcomes for magnetic resonance-guided focused ultrasound (MRgFUS) ablations of localized tumors. Images obtained immediately following MRgFUS ablation were inputs for voxel-wise supervised learning classifiers, trained using registered histology as a label for thermal necrosis. VX2 tumors in New Zealand white rabbits quadriceps were thermally ablated using an MRgFUS system under 3 T MRI guidance. Animals were re-imaged three days post-ablation and euthanized. Histological necrosis labels were created by 3D registration between MR images and digitized H&E segmentations of thermal necrosis to enable voxel-wise classification of necrosis. Supervised MPMR classifier inputs included maximum temperature rise, cumulative thermal dose (CTD), post-FUS differences in T2-weighted images, and apparent diffusion coefficient, or ADC, maps. A logistic regression, support vector machine, and random forest classifier were trained in red a leave-one-out strategy in test data from four subjects. In the validation dataset, the MPMR classifiers achieved higher recall and Dice than a clinically adopted 240 cumulative equivalent minutes at 43 °C (CEM 43) threshold (0.43) in all subjects. The average Dice scores of overlap with the registered histological label for the logistic regression (0.63) and support vector machine (0.63) MPMR classifiers were within 6% of the acute contrast-enhanced non-perfused volume (0.67). Voxel-wise registration of MPMR data to histological outcomes facilitated supervised learning of an accurate non-contrast MR biomarker for MRgFUS ablations in a rabbit VX2 tumor model.

Kiosk 7R-FB-09 - Feasibility of a Non-contrast Rapid Cardiac Magnetic Resonance Protocol in Heart Transplant Recipients for Detection of Acute Cardiac Allograft Rejection: Initial Experience FBom a Developing Country

Kiosk 7R-FB-09 - Feasibility of a Non-contrast Rapid Cardiac Magnetic Resonance Protocol in Heart Transplant Recipients for Detection of Acute Cardiac Allograft Rejection: Initial Experience FBom a Developing Country

Growth kinetics of venous tumor thrombus in patients with renal cell carcinoma

Some patients with renal cell carcinoma (RCC) present with venous tumor thrombus (VTT). The extent of the VTT is related to survival, so prompt surgical care is recommended. However, studies evaluating the natural history of VTT in patients with RCC are rare. We sought to evaluate the growth kinetics of VTT in patients with RCC using preoperative cross-sectional images. We identified patients who underwent radical nephrectomy and venous tumor thrombectomy at our institution from 01/2009 to 02/2022. We included those with a minimum of 2 adequate preoperative imaging studies (contrast-enhanced Computerized Tomography (CT), noncontrast Magnetic resonance imaging (MRI), or contrast-enhanced MRI), at least 14 days apart. We measured VTT in each study to calculate growth rate, and evaluated predictors of faster growth (demographics, histology, laterality, tumor diameter, and staging). To assess the relation between clinical variables and VTT growth, we used the Wilcoxon Rank-Sum, Kruskal-Wallis, and Spearman correlation tests. A total of 30 patients were included in the analysis. The median time interval between studies was 33 days. Patients were mostly Caucasian and Males (90% and 70%, respectively). Most patients underwent a CT scan as their initial imaging study (66%), followed with an MRI as second study (73%). The mean venous tumor thrombus growth rate was 0.3 mm/d (standard deviation of 0.5mm), and only rhabdoid/sarcomatoid differentiation showed an association with tumor thrombus growth rate (0.3 vs. 0.63 mm/d, P = 0.038). To the best of our knowledge, this is the first study evaluating the natural growth rate of venous tumor thrombus in patients with renal cell carcinoma. We found that tumor thrombi grew an average of 0.3 mm/d (1.0 cm/month) and that those with sarcomatoid and/or rhabdoid differentiation grew faster (0.63 mm/d). Further studies are needed to validate these results and provide a better understanding of tumor thrombus kinetics.

Multi-parametric non-contrast cardiac magnetic resonance for the differentiation between cardiac amyloidosis and hypertrophic cardiomyopathy.

To evaluate the ability of fast strain-encoded (SENC) cardiac magnetic resonance (CMR) derived myocardial strain and native T1 mapping to discriminate between hypertrophic cardiomyopathy (HCM) and cardiac amyloidosis. Ninety nine patients (57 with hypertrophic cardiomyopathy and 42 with cardiac amyloidosis) were systematically analysed. LV-ejection fraction, LV-mass index, septal wall thickness and native T1 mapping values were assessed. In addition, global circumferential and longitudinal strain and segmental circumferential and longitudinal strain in basal, mid-ventricular, and apical segments were calculated. A ratio was built by dividing native T1 values by basal segmental strain (T1-to-basal segmental strain ratio). Myocardial strain was equally distributed in apical and basal segments in HCM patients, whereas an apical sparing with less impaired apical strain was noticed in cardiac amyloidosis (apical-to-basal-ratio of 1.01 ± 0.23 versus 1.20 ± 0.28, p < 0.001). T1 values were significantly higher in amyloidosis compared to HCM patients (1170.7 ± 66.4ms versus 1078.3 ± 57.4ms, p < 0.001). The T1-to-basal segmental strain ratio exhibited high accuracy for the differentiation between the two clinical entities (Sensitivity = 85%, Specificity = 77%, AUC = 0.90, 95% CI = 0.81-0.95, p < 0.001). Multivariable analysis showed that age and the T1-to-basal-strain-ratio were the most robust factors for the differentiation between HCM and cardiac amyloidosis. The T1-to-basal-segmental strain ratio, combining information from segmental circumferential and longitudinal strain and native T1 mapping aids the differentiation between HCM and cardiac amyloidosis with high accuracy and within a fast CMR protocol, obviating the need for contrast agent administration.

Quantitative perfusion and water transport time model from multi b-value diffusion magnetic resonance imaging validated against neutron capture microspheres.

Quantification of perfusion in ml/100 g/min, rather than comparing relative values side-to-side, is critical at the clinical and research levels for large longitudinal and multi-center trials. Intravoxel incoherent motion (IVIM) is a non-contrast magnetic resonance imaging diffusion-based scan that uses a multitude of -values to measure various speeds of molecular perfusion and diffusion, sidestepping inaccuracy of arterial input functions or bolus kinetics. Questions remain as to the original of the signal and whether IVIM returns quantitative and accurate perfusion in a pathology setting. This study tests a novel method of IVIM perfusion quantification compared with neutron capture microspheres. We derive an expression for the quantification of capillary blood flow in ml/100 g/min by solving the three-dimensional Gaussian probability distribution and defining water transport time (WTT) as when 50% of the original water remains in the tissue of interest. Calculations were verified in a six-subject pre-clinical canine model of normocapnia, induced hypercapnia, and middle cerebral artery occlusion (ischemic stroke) and compared with quantitative microsphere perfusion. Linear regression analysis of IVIM and microsphere perfusion showed agreement (slope = 0.55, intercept = 52.5, ) with a Bland-Altman mean difference of . Linear regression between dynamic susceptibility contrast mean transit time and IVIM WTT asymmetry in infarcted tissue was excellent (, intercept = 0.3, ). Strong linear agreement was found between IVIM and reference standard infarct volume (slope = 1.01, ). The simulation of cerebrospinal fluid (CSF) suppression via inversion recovery returned a blood signal reduced by 82% from combined T1 and T2 effects. The accuracy and sensitivity of IVIM provides evidence that observed signal changes reflect cytotoxic edema and tissue perfusion and can be quantified with WTT. Partial volume contamination of CSF may be better removed during post-processing rather than with inversion recovery.

The effect of non-contrast enhanced MRA on patients with renal insufficiency and foot pain.

To investigate the feasibility of non-contrast magnetic resonance angiography of arteries and veins (NATIVE) sampling perfection with application optimized contrasts by using different flip angle evolution (SPACE) and quiescent interval single shot (QISS) in assessing foot arteries of patients with renal insufficiency and foot pain. Fifty-three patients (mean age = 44.2 ± 11.4 years, male: female = 27:26) underwent QISS and NATIVE-SPACE. The source images were reconstructed to maximum intensity projection and volume render. The image quality of QISS and NATIVE-SPACE was rated (0-3, poor to excellent), and was compared using Wilcoxon test. True or false positive was determined by comparing the findings of QISS and NATIVE-SPACE. The relative signal intensity of artery was obtained for each case, and was compared between QISS and NATIVE-SPACE using Mann Whitney test. The acquisition time of NATIVE-SPACE was significantly longer than that of QISS (178.4 ± 35.7 seconds vs 45.4 ± 8.9 seconds, P < .001). QISS had significantly lower image quality score versus NATIVE-SPACE (1.4 ± 0.5 vs 2.4 ± 0.6, P = .02). Fifteen percentage (8/53) NATIVE-SPACE cases had poor image quality due to the similarity of peak flow and minimum flow. The relative signal intensity was significantly lower in QISS versus NATIVE-SPACE (9.7 ± 1.3 vs 68.2 ± 12.4, P < .001). NATIVE-SPACE is valuable in evaluating foot arteries of patients with renal insufficiency. QISS can serve as an alternative test to NATIVE-SPACE.