Fat-suppressed T2-weighted Images Research Articles

Evaluation of Shimming Techniques on MRI Breast Image Quality at 1.5T.

The quality of all clinical MRI is dependent on B0 homogeneity, which is optimized during the shimming part of a prescan or preparatory phase before image acquisition. The purpose of this study was to assess shimming techniques clinically employed for breast MRI across our practice, and to determine factors that correlate with higher image quality for contrast-enhanced breast MRI at 1.5T. One hundred consecutive female patients were retrospectively collected with Institutional Review Board approval. Shimming-related parameters, including shim-box placement and shimming gradient offsets were extracted from prior contrast-enhanced 3D fat-suppressed T1-weighted gradient echo image acquisitions. Three breast radiologists evaluated these images for fat saturation, breast density, overall image quality, and artifacts. Technologist experience was also evaluated for variability of shimming. Generalized linear mixed models were used to compare acquisition parameters between fat saturation. P < 0.05 was considered as statistical significance. The percentage of soft tissue inside the field of view (FOV) (ie, Tissue/FOV) in the good fat-saturation group (0.37 ± 0.06) was significantly lower (P < 0.01) than that in the poor fat-saturation group (0.39 ± 0.06). Other shimming-related parameters were found not significantly affecting the fat-saturation outcomes. Technologists with more experience tended to have less variable shimming performance than junior technologists did. The quality of clinical MRI and especially breast MRI is highly dependent on shimming. Decreasing Tissue/FOV was associated with good image quality (good fat saturation). Optimization of shimming may require manual shimming or higher-order field-correction strategies.

Prevalence and clinical significance of discordant LI-RADS® observations on multiphase contrast-enhanced MRI in patients with cirrhosis.

To determine the prevalence and clinical significance of discordant LI-RADS® (Liver Imaging Reporting and Data System) liver observations on multiphase contrast-enhanced (MCE) magnetic resonance imaging (MRI) in patients with cirrhosis. This cross-sectional study included 93 cirrhosis patients who underwent 1.5 or 3 T MCE MRI for evaluation of hepatocellular carcinoma (HCC). Two abdominal radiologists independently reviewed T1-, T2-, diffusion-weighted unenhanced images as well as MCE T1-weighted fat-suppressed images and reported liver observations using LI-RADS®. Concordance were recorded for detection (co-detected by both radiologists or not), size category (< 10; 10-19; ≥ 20mm), and LI-RADS® category assignment as reportable (LR-3/4/5/M) and actionable (LR-4/5/M). The overall concordance (i.e., concordant in detection, size, and LR-category) was calculated with 95% confidence interval [CI], and separately for detection, size, and LR-category. Clinical significance of discordance was assessed as impact on follow-up imaging, referral for biopsy, liver transplant eligibility, or treatment modality. Reportable and actionable observations were overall concordant between two radiologists only in 32.3% [24.6, 41.0] and 40.1% [29.5, 51.5] of cases, respectively. Poor overall concordance was related to detection concordance of 52.0% [44.3, 59.5] and 62.5% [52.3, 71.8], as well as LR-category concordance of 73.7% [61.6, 83.1] and 70.9% [57.3, 81.6], for reportable and actionable observations, respectively. Discordant LI-RADS® observations would have impacted clinical management in 30 subjects (43.5%), most (66.7%) of whom were due to discordant detection. Discordant MRI LI-RADS® observations are common in patients with cirrhosis and may have potential implications for patient management.

Prediction for early recurrence of intrahepatic mass-forming cholangiocarcinoma: quantitative magnetic resonance imaging combined with prognostic immunohistochemical markers

BackgroundPartial hepatectomy is the first option for intrahepatic mass-forming cholangiocarcinoma (IMCC) treatment, which would prolong survival. The main reason for the poor outcome after curative resection is the high incidence of early recurrence (ER). The aim of this study was to investigate the combined predictive performance of qualitative and quantitative magnetic resonance imaging (MRI) features and prognostic immunohistochemical markers for the ER of IMCC.MethodsForty-seven patients with pathologically proven IMCC were enrolled in this retrospective study. Preoperative contrast-enhanced MRI and post-operative immunohistochemical staining of epidermal growth factor receptors (EGFR), vascular endothelial growth factor receptor (VEGFR), P53 and Ki67 were performed. Univariate analysis identified clinic-radiologic and pathological risk factors of ER. Radiomics analysis was performed based on four MRI sequences including fat suppression T2-weighted imaging (T2WI/FS), arterial phase (AP), portal venous phase (PVP), and delayed phase (DP) contrast enhanced imaging. A clinicoradiologic-pathological (CRP) model, radiomics model, and combined model were developed. And ROC curves were used to explore their predictive performance for ER stratification.ResultsEnhancement patterns and VEGFR showed significant differences between the ER group and non-ER group (P = 0.001 and 0.034, respectively). The radiomics model based on AP, PVP and DP images presented superior AUC (0.889, 95% confidence interval (CI): 0.783–0.996) among seven radiomics models with a sensitivity of 0.938 and specificity of 0.839. The combined model, containing enhancement patterns, VEGFR and radiomics features, showed a preferable ER predictive performance compared to the radiomics model or CRP model alone, with AUC, sensitivity and specificity of 0.949, 0.875 and 0.774, respectively.ConclusionsThe combined model was the superior predictive model of ER. Combining qualitative and quantitative MRI features and VEGFR enables ER prediction, thus facilitating personalized treatment for patients with IMCC.

Relationship between temporomandibular joint pain and magnetic resonance imaging findings in patients with temporomandibular joint disorders

The purpose of this study was to evaluate abnormal magnetic resonance imaging (MRI) findings related to temporomandibular joint (TMJ) pain. This study included 245 joints of 152 patients with temporomandibular disorders with anterior disc displacement; of these, 129 joints had joint pain whereas 116 joints had no joint pain. MRI was used to evaluate the reduction of anterior disc displacement, joint effusion, mandible condylar morphology, bone marrow oedema of the mandibular condyle, and signal intensity of the posterior disc attachment (PDA) on fat-suppressed T2-weighted images. The odds ratio (OR) for each MRI variable for the pain group versus the no pain group was computed using logistic regression analysis. Univariate logistic regression analysis showed significant correlations between TMJ pain and all MRI findings. Multivariate logistic regression analysis showed significant correlations with joint effusion (P=0.03, OR 2.21), bone marrow oedema (P<0.001, OR 11.75), and signal intensity of the PDA (P<0.001, OR 6.21). These results suggest that bone marrow oedema, high signal intensity of the PDA on fat-suppressed T2-weighted images, and joint effusion, in descending order of influence, are factors related to TMJ pain.

Radiomics and Machine Learning with Preoperative MRI May Accurately Predict the Histopathological Grades of Soft Tissue Sarcomas

Preoperative prediction of the grade of soft tissue sarcomas (STSs) is important because of its effect on the treatment plan, as adjuvant chemotherapy before surgery may significantly affect survival. The purpose of our study was to assess the value of radiomics features in distinguishing histological grades of STSs. Eighty STS patients (18 low-grade [grade I]; 62 high-grade [grade II and III]) undergoing T1WI and fat-suppressed T2WI were enrolled in the primary set. The T1WI and fat-suppressed T2WI were analysed to derive volume-based data of the entire lesion. Multiple machine learning methods were trained to establish classification models to predict STS grades. We tested the model with a validation set (33 patients; 7 low-grade; 26 high-grade). The machine learning method performance varied with the different machine learning algorithms used. The best classification model for the prediction of STS grade, a combination of feature selection by recursive feature elimination (RFE) and random forest (RF) classification algorithm with synthetic minority over-sampling technique (SMOTE), had an area under the curve (AUC) of 0.9615 (95% confidence interval [CI], 0.8944-1) in the validation set. The accuracy, sensitivity, and specificity of the best method were 93.94, 96.15, and 85.71% in the validation set, respectively. Radiomics feature-based machine learning methods are useful for distinguishing STS grades, which improve the precision of preoperative diagnosis and may affect treatment strategies. Funding: This work was financially supported by the National Natural Science Foundation of China (grant numbers 81370035, and 81230030). Declaration of Interest: The authors declare that they have no competing interests. Ethical Approval: This retrospective study was approved by the local ethics committee of our hospital, which waived the need for patients’ informed consent.

IgG4-related disease: rare presentation as a soft-tissue mass in the thigh of an adolescent.

We report a case of a 16-year-old boy who presented a soft-tissue mass in the anterior compartment of the right thigh discovered by positron emission tomography/computed tomography within the work-up of unexplained prolonged inflammatory syndrome. The mass has no calcification. Subsequently, magnetic resonance imaging of the femoral triangle was carried out. Axial short tau inversion recovery images showed a 3.5-cm ill-defined mass in the femoral triangle with focal areas of hypointensity, which suggests that there might be fibrosis or hemosiderin within the tumor. Axial T1-weighted images showed a slight hyperintense mass involving the iliopsoas muscle. Contrast-enhanced fat-suppressed T1-weighted imaging showed a heterogeneous solid enhancement. Adjacent thick fascia enhancement of the vastus intermedius and the vastus lateralis muscles extending from the mass as a tail-like margin suggested the infiltrative spread of the tumor along the fascial plane. The mass and the lymphadenopathy were excised. Immunohistochemically, tumor cells were staining for muscle actin and desmin. Many plasma cells were IgG4+ (175per high-power field) with a ratio IgG4+/IgG+ of 50%. The diagnosis of IgG4-related disease (IgG4-RD) was made. Although a diffuse array of musculoskeletal symptoms has been observed in IgG4-related disease, reports of biopsy-proven musculoskeletal involvement of the limb are rare. We showed the radiological features of IgG4-RD presenting as a soft-tissue mass of the thigh. Musculoskeletal involvement, clinical significance, and treatment of IgG4-RD are also discussed.

Bone Pseudometastasis on 18F-FDG PET in Japanese Patients With Esophageal Cancer.

False-positive bone lesions mimicking bone metastases (bone pseudometastasis) on F-FDG PET/CT have often been reported in patients with esophageal cancer. We aimed to evaluate the prevalence and features of these lesions in Japanese patients with esophageal cancer. In this retrospective study, we analyzed 83 FDG PET/CT studies for initial staging of esophageal cancer, and extracted patients with 1 or more localized high uptake sites with no subsequent progression, which were therefore judged to be bone pseudometastasis. The FDG PET/CT imaging features of the bone pseudometastasis were evaluated, and other available imaging and clinical features reviewed. Of the 83 patients, 7 had bone pseudometastasis. All 7 were males diagnosed with squamous cell cancer, of which 5 had T1a tumors. Bone pseudometastasis showed normal or ill-defined hyperdense (nonosteolytic) sites compared with the surrounding area on the CT. Additionally, accumulation in the upper vertebral levels of each case was contiguously high compared with the lumbar spines (we named this finding "contiguous accumulation"). On MRI, these findings were visualized as low signals on T1-weighted imaging (T1WI) and T2WI images but were unclear on fat-suppressed T2WI images. Among all PET/CT performed for staging of esophageal cancer, 8.3% demonstrated bone pseudometastasis characterized by heterogeneous distribution with severe fatty degeneration of bone marrow accompanied by contiguous accumulation. Caution is required during diagnoses of bone lesions in esophageal cancer patients in Japan to prevent inappropriate therapeutic choices.

MR Imaging-based Evaluation of Mesenteric Ischemia Caused by Strangulated Small Bowel Obstruction and Mesenteric Venous Occlusion: An Experimental Study Using Rabbits.

Purpose:This study assessed the MRI findings of strangulated small bowel obstruction (SBO) and mesenteric venous occlusion (MVO) in a rabbit model using 3T MRI.Materials and Methods:Twenty rabbits were included in this study. The strangulated SBO and MVO models were generated via surgical procedures in nine rabbits, and sham surgery was performed in two rabbits. The success of generating the models was confirmed via angiographic, macroscopic, and microscopic findings after the surgical procedure. MRI was performed before and 30 min after inducing mesenteric ischemia. T1-weighted images (T1WIs), T2-weighted images (T2WIs), and fat-suppressed T2WIs (FS-T2WIs) were obtained using the BLADE technique, and fat-suppressed T1WIs (FS-T1WIs) were obtained. The signal intensities of the affected bowel before and after the surgical procedures were visually categorized as high, iso, and low intense compared with the findings for the normal bowel wall on all sequences. Bowel wall thickness was measured, and the signal intensity ratio (SI ratio) was calculated using the signal intensities of the bowel wall and psoas muscle.Results:Angiographic, macroscopic, and microscopic findings confirmed that all surgical procedures were successful. The ischemic bowel wall was thicker than the normal bowel. The bowel wall was thicker in the MVO model (3.17 ± 0.55 mm) than in the strangulated SBO model (2.26 ± 0.46 mm). The signal intensity and SI ratio of the bowel wall were significantly higher after the procedure than before the procedure on all sequences in both models. The mesentery adjacent to the ischemic bowel loop exhibited a high signal intensity in all animals on FS-T2WIs.Conclusion:Non-contrast MRI can be used to evaluate mesenteric ischemia caused by strangulated SBO and MVO. FS-T2WIs represented the best modality for depicting the high signal intensity in the bowel wall and mesentery caused by ischemia.

Development and External Validation of an MRI-Based Radiomics Nomogram for Pretreatment Prediction for Early Relapse in Osteosarcoma: A Retrospective Multicenter Study

Background: To develop and externally validate an MR-based radiomics nomogram from retrospective multicenter datasets for pretreatment prediction of early relapse (≤1 year) in osteosarcoma after surgical resection. Methods: This multicenter study retrospectively enrolled 93 patients (training cohort: 62 patients from four hospitals; validation cohort: 31 patients from two hospitals) with clinicopathologically confirmed osteosarcoma who received neoadjuvant chemotherapy and surgical resection at six hospitals between January 2009 and October 2017. Radiomics feature was extracted from contrast-enhanced fat-suppressed T1-weighted (CE FS T1-w) images. A radiomics signature was constructed with least absolute shrinkage and selection operator (LASSO) regression. The radiomics nomogram that incorporated the radiomics signature and subjective MRI-assessed risk factors was developed to predict early relapse with a multivariate logistic regression model in the training cohort and validated in the external validation cohort. The performance of the nomogram was assessed by its discrimination, calibration, and clinical usefulness. Findings: The radiomics nomogram, which incorporated a radiomics signature (consisted of six selected features) and subjective MRI-assessed risk factors (joint invasion and perivascular involvement) from the multicenter datasets, achieved good discrimination in the training cohort (C-index: 0.907, 95% CI: 0.838-0.977) and external validation cohort (C-index: 0.811, 95% CI: 0.653-0.970), and good calibration. Decision curve analysis suggested that the combined nomogram was clinically useful. Interpretation: The proposed MRI-based radiomics nomogram could provide a nonvasive tool to develop a model for pretreatment prediction of early relapse in osteosarcoma, which has potential to lead to improvement of personalized pretreatment management of osteosarcoma. Funding: This research is supported by the National Key Research and Development Program of China (No. 2017YFC1309100), the National Natural Science Foundation of China (Grant Nos. 81871510, 81771912). Declaration of Interest: No competing interest exists. Ethical Approval: This multicentric study was approved by the ethics committee of every participating hospital and was conducted in accordance with the Declaration of Helsinki.

Fully Automated Diagnosis of Anterior Cruciate Ligament Tears on Knee MR Images by Using Deep Learning.

To investigate the feasibility of using a deep learning-based approach to detect an anterior cruciate ligament (ACL) tear within the knee joint at MRI by using arthroscopy as the reference standard. A fully automated deep learning-based diagnosis system was developed by using two deep convolutional neural networks (CNNs) to isolate the ACL on MR images followed by a classification CNN to detect structural abnormalities within the isolated ligament. With institutional review board approval, sagittal proton density-weighted and fat-suppressed T2-weighted fast spin-echo MR images of the knee in 175 subjects with a full-thickness ACL tear (98 male subjects and 77 female subjects; average age, 27.5 years) and 175 subjects with an intact ACL (100 male subjects and 75 female subjects; average age, 39.4 years) were retrospectively analyzed by using the deep learning approach. Sensitivity and specificity of the ACL tear detection system and five clinical radiologists for detecting an ACL tear were determined by using arthroscopic results as the reference standard. Receiver operating characteristic (ROC) analysis and two-sided exact binomial tests were used to further assess diagnostic performance. The sensitivity and specificity of the ACL tear detection system at the optimal threshold were 0.96 and 0.96, respectively. In comparison, the sensitivity of the clinical radiologists ranged between 0.96 and 0.98, while the specificity ranged between 0.90 and 0.98. There was no statistically significant difference in diagnostic performance between the ACL tear detection system and clinical radiologists at P < .05. The area under the ROC curve for the ACL tear detection system was 0.98, indicating high overall diagnostic accuracy. There was no significant difference between the diagnostic performance of the ACL tear detection system and clinical radiologists for determining the presence or absence of an ACL tear at MRI.© RSNA, 2019Supplemental material is available for this article.

Fully automated segmentation of wrist bones on T2-weighted fat-suppressed MR images in early rheumatoid arthritis.

Magnetic resonance imaging (MRI) allows accurate determination of soft tissue and bone inflammation in rheumatoid arthritis. Inflammation can be measured semi-quantitatively using the well-established RA-MRI scoring system (RAMRIS), but its application is time consuming in routine clinical practice. To fully realize an automated quantitation of inflammation scoring for clinical use, automatic segmentation of the wrist bones on MR imaging is needed. Most previous studies extracted the wrist bones on T1-weighted (T1W) MR images, and then used registration to segment T2W fat-suppressed images for bone marrow oedema quantification, introducing spatial errors into the process. Relatively little work has tried segmentation directly from T2W fat-suppressed images and no prior study have used convolution neural network (CNN) to segment the wrist bones. The purpose of this study is to develop a CNN-based algorithm for automated segmentation of the wrist bones in early rheumatoid arthritis (ERA) patients on T2W fat-saturated MR images. As preliminary tests indicated that out-of-the-box segmentation CNN U-net performance was compromised by close apposition of wrist tendons and bone, we separated the volumes prior to segmentation by using classification CNN Inception V3 to group images with similar features. The classified images were then segmented by individually trained U-net. We trained the networks on 40 cases and tested them on 11 cases derived from an MR imaging dataset of 51 patients with varying severity of ERA. We obtained a wrist bone segmentation with an average dice similarity coefficient (DICE) of 0.888±0.014, when compared to a manually drawn label. These results are comparable to existing atlas-based methods. We have developed a fully automatic method to segment the wrist bones in ERA patients of varying severity directly from T2W fat-suppressed MR images. This compares well with manually drawn labels.

MRI of skeletal muscles in patients with idiopathic inflammatory myopathies: characteristic findings and diagnostic performance in dermatomyositis

ObjectiveTo define the characteristic findings on MRI of skeletal muscles in patients with dermatomyositis (DM) relative to those in patients with other idiopathic inflammatory myopathies (IIMs) and to assess their...

Background parenchymal enhancement assessment: Inter- and intra-rater reliability across breast MRI sequences

ObjectiveTo evaluate inter- and intra-rater reliability of background parenchymal enhancement (BPE) assessment across breast MRI sequences. Materials and methodsInstitutional review board approval was obtained and the requirement for consent was waived. Three radiologists qualitatively categorized BPE on 150 breast MRI using a four-point scale (minimal, mild, moderate or marked) according to BI-RADS category system. According to MR-sequence used for the assessment of BPE, inter-rater and intra-rater reliability across a simulated reading strategy with four options was performed: (1) initial contrast-enhanced (CE) fat-suppressed T1-weighted images (2) initial CE subtracted images (3) maximum-intensity-projection (MIP) of the first CE subtracted images (4) combination of initial CE fat-suppressed T1-weighted, initial CE subtracted and MIP images. Raters repeated BPE assessment of 45 breast MRI four weeks after the initial assessment. Gwet’s AC1 index with ordinal weights was used to assess reliabilities. ResultsGwet’s index for the reliability among the three raters was 0.68 (0.63-0.74) using initial contrast-enhanced fat-suppressed T1 weighted images, 0.74 (0.69-0.80) using subtracted images, 0.80 (0.76-0.83) using MIP, 0.80 (0.77-0.84) using a combination of the initial contrast-enhanced fat-suppressed T1 weighted, initial contrast-enhanced subtracted and MIP images. Test-retest reliability was 0.81 (0.60–1.00) for rater 1, 0.77 (0.55-0.98) for rater 2, 0.79 (0.59-0.99) for rater 3 using the combination of initial contrast-enhanced fat-suppressed T1 weighted, initial contrast-enhanced subtracted and MIP images. ConclusionsOverall, the combination of all CE MRI images showed the highest reliability of BPE assessment. However, MIP showed a high reliability with lower reading time compared to the combination of all CE MRI images.

The utility of MRI histogram and texture analysis for the prediction of histological diagnosis in head and neck malignancies

BackgroundTo assess the utility of histogram and texture analysis of magnetic resonance (MR) fat-suppressed T2-weighted imaging (Fs-T2WI) for the prediction of histological diagnosis of head and neck squamous cell carcinoma (SCC) and malignant lymphoma (ML).MethodsThe cases of 57 patients with SCC (45 well/moderately and 12 poorly differentiated SCC) and 10 patients with ML were retrospectively analyzed. Quantitative parameters with histogram features (relative mean signal, coefficient of variation, kurtosis and skewness) and gray-level co-occurrence matrix (GLCM) features (contrast, correlation, energy and homogeneity) were calculated using Fs-T2WI data with a manual tumor region of interest (ROI).ResultsThe following significantly different values were obtained for the total SCC versus ML groups: relative mean signal (3.65 ± 0.86 vs. 2.61 ± 0.49), contrast (72.9 ± 16.2 vs. 49.3 ± 8.7) and homogeneity (2.22 ± 0.25 × 10− 1 vs. 2.53 ± 0.12 × 10− 1). In the comparison of the SCC histological grades, the relative mean signal and contrast were significantly lower in the poorly differentiated SCC (2.89 ± 0.63, 56.2 ± 12.9) compared to the well/moderately SCC (3.85 ± 0.81, 77.5 ± 13.9). The homogeneity in poorly differentiated SCC (2.56 ± 0.15 × 10− 1) was higher than that of the well/moderately SCC (2.1 ± 0.18 × 10− 1).ConclusionsParameters obtained by histogram and texture analysis of Fs-T2WI may be useful for noninvasive prediction of histological type and grade in head and neck malignancy.

Early Detection of Central Nervous System Relapse of Pediatric Leukemia with Measurement of Optic Nerve Sheath Diameter on MRI

Leukemia is the most common pediatric malignancy. Central Nervous System (CNS) is the most frequently involved extramedullary location at diagnosis and at relapse. To determine if Magnetic Resonance Imaging (MRI) findings of optic nerves should contribute to early detection of CNS relapse in pediatric leukemia. Twenty patients (10 boys, 10 girls; mean age 8,3 years, range 4-16 years) with proven CNS relapse of leukemia followed up between 2009 and 2017 in our institution were included. Orbital MRI exams performed before and during CNS relapse were reviewed retrospectively. Forty optic nerves with Optic Nerve Sheaths (ONS) and Optic Nerve Heads (ONH) were evaluated on fat-suppressed T2-weighted TSE axial MR images. ONS diameter was measured from the point 10 mm posterior to the globe. ONS distension and ONH configuration were graded as 0, 1 and 2. Before CNS relapse, right mean ONS diameter was 4.52 mm and left was 4.61 mm which were 5.68 mm and 5.66 mm respectively during CNS relapse showing a mean increase of 25% on right and 22% on left. During CNS relapse, ONS showed grade 0 distension in 15%, grade 1 in 60%, grade 2 in 25% and ONH demonstrated grade 0 configuration in 70%, grade 1 in 25% and grade 2 in 5% of the patients. MRI findings of optic nerves may contribute to diagnose CNS relapse by demonstrating elevated intracranial pressure in children with leukemia.

Assessment of acute obstructive pancreatitis by magnetic resonance imaging: Predicting the occurrence of pancreatic fistula following pancreatoduodenectomy.

The aim of the present study was to assess the effect of preoperative acute obstructive pancreatitis on the risk of the occurrence of pancreatic fistula (PF) following pancreaticoduodenectomy. A total of 22 patients who developed postoperative PF were carefully matched with 22 control patients without PF according to demographic data, pancreatic pathology, presenting symptoms and other surgery-associated parameters. These parameters were compared between these two groups. The mean pancreatic apparent diffusion coefficient (ADC) values in the fistula group were 1.14±0.31×10-3 mm2/s, which was significantly decreased compared with the non-fistula group (1.48±0.44×10-3 mm2/s) (P=0.005). The pancreas-muscle signal intensity (SI) ratio on fat-suppressed T1 weighted image (rT1) in the fistula group was 1.71±0.25, which was significantly increased compared with the non-fistula group (1.25±0.29) (P<0.001). The pancreas-muscle SI ratios on fat-suppressed T2 weighted image (T2WI) in the fistula group and the non-fistula group were 0.72±0.08 and 0.62±0.07, respectively (P=0.79). There was no significant difference in pancreas-muscle SI ratio on fat-suppressed T2-weighted image (rT2) value between these two groups. Based on the receiver operating characteristic curve, the optimal cut-off value of ADC as a criterion for prediction of pancreatic fistula was 1.29×10-3 mm2/s, which yielded a sensitivity of 77.3% and a specificity of 63.6%. In conclusion, the severity of acute obstructive pancreatitis was negatively associated with ADC values and pancreas-muscle SI ratio on rT1 images, which may be useful for predicting the occurrence of PF preoperatively.

Volume change in infrapatellar fat pad is associated not with obesity but with cartilage degeneration.

Infrapatellar fat pad has been implicated in knee osteoarthritis. We examined whether infrapatellar fat pad volume is associated with quantitative cartilage changes using magnetic resonance imaging T1ρ mapping. Fifty-eight knees of knee pain patients (19 men, 39 women, mean age 57.0 [range 29-85] years) who were conservatively managed and had >1 T1ρ mapping images taken over time were evaluated. We used three slices from the medial femoral and tibial cartilage; areas showing T1ρ values <130 ms and >50 ms were designated as having cartilage degeneration. Cases were categorized into three groups: Improvement, No Change, and Deterioration. Fat-suppressed T2-weighted sagittal magnetic resonance images were used for measuring infrapatellar fat pad volume. Percent change in infrapatellar fat pad volume was -5.01 ± 5.66%, -2.06 ± 4.92%, and 0.05 ± 6.09% in the Improvement (n = 22), No Change (n = 22), and Deterioration (n = 14) groups, respectively, demonstrating significantly reduced infrapatellar fat pad volume in the Improvement group (p < 0.05). Multivariate regression analyses revealed that the percent change in infrapatellar fat pad volume significantly affected T1ρ change category independent of age, sex, follow-up period, baseline infrapatellar fat pad volume, and Kellgren-Lawrence grade. Infrapatellar fat pad volume and obesity or body weight change showed no correlation. Infrapatellar fat pad volume was reduced in patients with improved quantitative cartilage assessment on magnetic resonance imaging T1ρ mapping. This is the first study demonstrating associations between quantitative cartilage changes and infrapatellar fat pad morphological changes, suggesting a detrimental role of infrapatellar fat pad volume in articular cartilage degeneration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

MRI T2-Weighted Imaging and Fat-Suppressed T2-Weighted Imaging Image Fusion Technology Improves Image Discriminability for the Evaluation of Anal Fistulas.

To explore whether MRI fusion technology (combined T2-weighted imaging [T2WI] and fat-suppressed T2WI [T2WI-FS]) improves signal differences between anal fistulas and surrounding structures. A total of 32 patients with confirmed diagnoses of anal fistula were retrospectively studied. All available T2WI and T2WI-FS images for each patient were used to generate fusion image (T2WI-Fusion) based on the addition of gray values obtained from each pixel via an MR post-processing work station. The discriminability of fistula, perianal sphincter, and perianal fat in T2WI, T2WI-FS, and T2WI-Fusion images was quantified with Fisher's scoring algorithm. For subjective visual image assessment by researchers, five-point scale scores were determined using a modified double-stimulus continuous quality-scale test to evaluate T2WI-FS, T2WI, enhanced axial three-dimensional-volumetric interpolated breath-hold examination (3D-VIBE), and T2WI-Fusion sequence images. The differences were subsequently compared. Mean Fisher scores for fistulas vs. sphincters obtained from T2WI-Fusion (FFusion-fistula = 6.56) were significantly higher than those from T2WI (FT2WI-fistula = 3.35) (p = 0.001). Mean Fisher scores for sphincters vs. fat from T2WI-Fusion (FFusion-sphincter = 10.84) were significantly higher than those from T2WI-FS (FSFS-sphincter = 2.57) (p = 0.001). In human assessment, T2WI-Fusion showed the same fistula discriminability as T2WI-FS, and better sphincter discriminability than T2WI. Overall, T2WI-Fusion showed better discriminability than T2WI, T2WI-FS, and enhanced 3D-VIBE images. T2WI and T2WI-FS fusion technology improves signal differences between anal fistulas and surrounding structures, and may facilitate better evaluation of anal fistulas and sphincters.

Standing magnetic resonance imaging of distal phalanx fractures in 6 cases of Thoroughbred racehorse.

Six Thoroughbred racehorses with palmar process fractures of the distal phalanx were evaluated with standing magnetic resonance imaging (sMRI). In all the cases, the fractures were detectable on T1-weighted images and fat-suppressed images. Furthermore, multi-planar reconstruction images were useful for assessing the articular involvement of the fractures. Follow-up sMRI was obtainable in 3 cases, which revealed that the area of high signal intensity on fat-suppressed images decreased over time as symptoms improved. Our findings support the use of sMRI for the detailed evaluation of distal phalanx fractures including their articular involvement and the healing process.

New scoring system in assessment of Hoffa's fat pad synovitis: A comparative study with established scoring systems.

AIMTo investigate the reliability of the established and new scoring methods for Hoffa’s fat pad synovitis using magnetic resonance imaging (MRI).METHODSA total of 139 knees of 115 patients who underwent MRI of the knee with and without gadolinium contrast were enrolled in this study. Proton density (PD)-weighted, PD-weighted fat-suppressed (PD-FS), and postcontrast T1-weighted fat-suppressed (T1CE) images were used for evaluation. Using contrast and non-contrast images, our grading method for synovitis was performed to measure synovial thickness and signal intensity changes of the fat pad [Synovial membrane (SM) score], which was compared with the established methods, including MRI Osteoarthritis Knee Score (MOAKS), parapatellar synovitis score, Whole-Organ Magnetic Resonance Imaging Score (WORMS), and suprapatellar effusion diameter. Intraclass correlation coefficients (ICC) for intra and interobserver reproducibility and Spearman correlation coefficients (r) were calculated for the parapatellar synovitis score and each scoring method.RESULTSAll of the scores presented substantial to almost perfect intrareliability. Among three readers, effusion diameter had substantial to almost perfect interreliability (ICC = 0.68-0.81) and WORMS had substantial interreliability (ICC = 0.61-0.70). For two out of three readers, there was substantial interreliability for the thickness score in T1CE (ICC = 0.55-0.69), SM scores in T1CE (ICC = 0.56-0.78) and PD-FS (ICC = 0.51-0.79), and parapatellar synovitis score in T1CE (ICC = 0.53-0.72). The parapatellar synovitis score was significantly correlated with the thickness score in T1CE (r = 0.70) and the SM score in T1CE (r = 0.81) and PD-FS (r = 0.65).CONCLUSIONThe newly proposed quantitative thickness score on T1CE and the semi-quantitative SM score on T1CE and PD-FS can be useful for Hoffa’s fat pad synovitis.