Purpose
To compare qualitative results obtained from computer-aided dual-ratio analysis on T1-weighted two-point Dixon, with T2*-corrected multi-echo Dixon and T2-corrected multi-echo single-voxel MR ...spectroscopy sequence (MRS) for evaluation of liver fat and iron at 3T.
Methods and materials
This retrospective, HIPAA-compliant, IRB-approved study included 479 patients with known or suspected liver disease. Two-point Dixon, multi-echo Dixon, and MR spectroscopy sequences were performed for each patient at 3T. A receiver-operating characteristic analysis was performed to compare the diagnostic performance in 80 patients using biopsy as the standard. Sensitivity, specificity, PPV, and NPV of qualitative two-point Dixon results, multi-echo Dixon (PDFF and R2*), and MRS (fat fraction and R2 water) for detection of hepatic steatosis and siderosis were assessed.
Results
Fat fractions obtained from MRS and multi-echo Dixon have equivalent accuracy for detection of hepatic steatosis (AUC, sensitivity and specificity: 0.90 vs 0.88, 0.77 vs. 0.82, and 0.90 vs. 0.82), but the optimal cutoff value is higher for MRS (6.05% vs. 3.4%). The dual-ratio Dixon discrimination technique showed high negative predictive value for detection of hepatic steatosis and siderosis (0.90 and 0.94, respectively). R2* from multi-echo Dixon and R2
water
from MRS have equivalent accuracy for detection of iron overload at 3T (AUC 0.89 vs. 0.88). The optimal cutoff for R2* and R2
water
are 60.5 s
−1
and 40.85 s
−1
, respectively.
Conclusion
The computer-aided dual-ratio discrimination with two-point Dixon is a useful qualitative screening tool with high negative predictive value for hepatic steatosis and iron overload. Multi-echo Dixon and MRS have similar accuracy for detection of hepatic steatosis and iron overload at 3 Tesla.
Autoimmune pancreatitis (AIP) is a rare chronic relapsing steroid-responsive fibroinflammatory disorder of the pancreas that is likely caused by immune dysregulation. It is now thought that AIP ...consists of two distinct clinicopathologic syndromes currently designated as types 1 and 2.
A current update on etiopathogenesis, pathology, and clinical and imaging findings of AIP is provided with an emphasis on diagnosis and management.
There is a heterogeneous group of noninfectious gastroenterocolitis syndromes that are characterized by immune dysregulation. Recent advances in pathologic analysis have allowed for better ...characterization of many of these disorders. Some entities demonstrate characteristic disease distribution, epidemiologic features, natural history, and response to specific therapy. For instance, celiac disease occurs in genetically susceptible individuals who are sensitive to gluten, eosinophilic esophagitis is an immune response to ingested allergens, and microscopic colitis predominantly occurs in older patients with chronic diarrhea and is induced or exacerbated by drugs. Eosinophilic gastroenteritis has a variety of clinical and imaging manifestations. Crohn disease and ulcerative colitis are multifactorial immune-mediated chronic inflammatory disorders and have become increasingly prevalent in recent years. Multidetector computed tomography and magnetic resonance imaging provide valuable information that may be used to diagnose these conditions, guide treatment, and assess changes after treatment, and the role of imaging in evaluating response to therapy continues to evolve and expand.
MR elastography (MRE), first described in 1995 and FDA-cleared in 2009, has emerged as an important tool for noninvasively detecting and staging liver fibrosis in patients with known or suspected ...chronic liver disease. This review focuses on a series of practical questions about the clinical use of MRE. Most head-to-head comparison studies with other laboratory and imaging-based tests have concluded that MRE has the highest diagnostic performance among tests for staging liver fibrosis. Limitations in the accuracy of biopsy as a standard of truth in staging liver fibrosis are increasingly being recognized. MRE-based measurements show promise as quantitative surrogates of disease severity and predictors of important clinical outcomes. The appropriate role of MRE in the management of patients with chronic liver disease is being actively incorporated into recognized clinical guidelines. Growing evidence shows that MRI measurement of elevated liver fat is the most important single biomarker for detecting nonalcoholic steatohepatitis (NASH) and that MRE-based liver stiffness is the most important single biomarker for detecting at-risk NASH (i.e., NASH with stage ≥ F2 fibrosis). Advances in MRE technology are offering higher precision and new biomarkers, which have potential to allow independent assessment of inflammation and other histologic processes in addition to fibrosis.
Acute pancreatitis is one of the most common conditions for which emergent imaging is indicated. Alcohol consumption and cholelithiasis are the most common causes of acute pancreatitis in adults, ...whereas the majority of cases in children are idiopathic or secondary to trauma. A wide variety of structural and biochemical abnormalities may also cause pancreatitis. Although in some cases it is difficult to identify the specific cause of the disease radiologically, certain uncommon types of acute or chronic pancreatitis may have unique imaging features that can help the radiologist make an accurate diagnosis. These unusual types include autoimmune pancreatitis, groove pancreatitis, tropical pancreatitis, hereditary pancreatitis, and pancreatitis in ectopic or heterotopic pancreatic tissue. Pancreatitis may occasionally be seen in association with cystic fibrosis or pancreas divisum, or secondary to worm infestation of the pancreaticobiliary tree (eg, by Ascaris lumbricoides). In addition, primary pancreatic and duodenal masses may occasionally manifest as acute or recurrent acute pancreatitis. Knowledge of the classic imaging findings of these entities allows prompt recognition of the relevant pathologic condition, thereby preventing misdiagnosis and subsequent inappropriate or delayed management.
To develop and test a deep learning approach named Convolutional Neural Network (CNN) for automated screening of T
-weighted (T
WI) liver acquisitions for nondiagnostic images, and compare this ...automated approach to evaluation by two radiologists.
We evaluated 522 liver magnetic resonance imaging (MRI) exams performed at 1.5T and 3T at our institution between November 2014 and May 2016 for CNN training and validation. The CNN consisted of an input layer, convolutional layer, fully connected layer, and output layer. 351 T
WI were anonymized for training. Each case was annotated with a label of being diagnostic or nondiagnostic for detecting lesions and assessing liver morphology. Another independently collected 171 cases were sequestered for a blind test. These 171 T
WI were assessed independently by two radiologists and annotated as being diagnostic or nondiagnostic. These 171 T
WI were presented to the CNN algorithm and image quality (IQ) output of the algorithm was compared to that of two radiologists.
There was concordance in IQ label between Reader 1 and CNN in 79% of cases and between Reader 2 and CNN in 73%. The sensitivity and the specificity of the CNN algorithm in identifying nondiagnostic IQ was 67% and 81% with respect to Reader 1 and 47% and 80% with respect to Reader 2. The negative predictive value of the algorithm for identifying nondiagnostic IQ was 94% and 86% (relative to Readers 1 and 2).
We demonstrate a CNN algorithm that yields a high negative predictive value when screening for nondiagnostic T
WI of the liver.
2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:723-728.
Objective
To analyze the findings of proctitis in patients with laboratory-confirmed Mpox and correlate the patient clinical presentation and laboratory findings.
Methods
21 patients with ...PCR-positive Mpox who obtained abdominopelvic CT were retrospectively identified by electronic medical record search. Three radiologists independently evaluated CT images, measuring rectal wall thickness (cm), degree of perirectal fat stranding on a 5-point Likert scale, and size of perirectal lymph nodes (cm, short axis). Mann–Whitney U-test (Wilcoxon rank sum test) was used to assess the association of rectal wall thickness and perirectal fat standing between patients with rectal symptoms and patients without rectal symptoms.
Results
20 of 21 patients presented with perirectal fat stranding, with mean Likert score of 3.0 ± 1.4, indicating moderate perirectal stranding. Mean transverse rectal wall thickness was 1.1 ± 0.5 cm (range 0.3–2.3 cm); it was thicker among patients with HIV (1.2 cm vs 0.7 cm;
p
= .019). Mean perirectal fat stranding was greater among patients presenting with HIV, and with rectal symptoms, though not significantly so. 17/21 (81%) patients had abnormal mesorectal lymph nodes by at least two of three readers, with mean short-axis measurement 1.0 ± 0.3 cm (range 0.5–1.6 cm). Multiple linear regression showed no significant correlation between rectal thickness and laboratory values or HIV status.
Conclusion
Nearly all patients with Mpox who presented with additional symptoms warranting a CT demonstrated proctitis. Degree of proctitis varied greatly within the cohort, with greatest thickening among patients with HIV. Physicians should have a high suspicion for proctitis in patients with suspected Mpox.
Abstract Congenital absence of portal vein is a rare anomaly that results from aberrant venous development in early embryonic life. The intestinal and splenic venous drainage bypass the liver and may ...drain directly into inferior vena cava or the left renal vein or the left hepatic vein. This rare anomaly is commonly associated with other congenital malformations and generally limited to females. We describe a rare case of aberrant portal vein development with congenital portocaval shunt (end-to-side) in a 3.5-year male child associated with cardiac defects (atrial and ventricular septal defects), skeletal deformities (flexion deformity and clinodactyly of digits and toes), and lichen planus with café au lait macules of skin.
Abstract Incidental splenic lesions are frequently encountered at imaging performed for unrelated causes. Splenic cysts, hemangiomas, and lymphomatous involvement are the most frequently encountered ...entities. Computed tomography and sonography are commonly used for initial evaluation with magnetic resonance imaging reserved as a useful problem-solving tool for characterizing atypical and uncommon lesions. The value of magnetic resonance imaging lies in classifying these lesions as either benign or malignant by virtue of their signal-intensity characteristics on T1- and T2-weighted imaging and optimal depiction of internal hemorrhage. Dynamic contrast-enhanced sequences may improve the evaluation of focal splenic lesions and allow characterization of cysts, smaller hemangiomas, and hamartomas. Any atypical or unexplained imaging feature related to an incidental splenic lesion requires additional evaluation and/or follow-up. Occasionally, biopsy or splenectomy may be required for definitive assessment given that some of tumours may demonstrate uncertain biologic behavior.
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