Imaging of Pancreaticobiliary Maljunction.

Pancreaticobiliary maljunction (PBM) is a congenital malformation in which the pancreatic and bile ducts join outside the duodenal wall, usually forming a long common channel. A major issue in patients with PBM is the risk of biliary cancer. Because the sphincter of Oddi does not regulate the pancreaticobiliary junction in PBM, pancreatic juice frequently refluxes into the biliary tract and can cause various complications, including biliary cancer. Most cancers arise in the gallbladder or dilated common bile duct, suggesting that bile stasis is related to carcinogenesis. Early diagnosis and prophylactic surgery to reduce the risk of cancer are beneficial. The diagnosis of PBM is made mainly on the basis of imaging findings. The development of diagnostic imaging modalities such as multidetector CT and MR cholangiopancreatography has provided radiologists with an important role in diagnosis of PBM and its complications. Radiologists should be aware of PBM despite the fact that it is rare in non-Asian populations. In this review, the authors present an overview of PBM with emphasis on diagnosis and management of PBM and its complications. For early diagnosis, the presence of extrahepatic bile duct dilatation or gallbladder wall thickening may provide a clue to PBM with or without biliary dilatation, respectively. The pancreaticobiliary anatomy should be closely examined if imaging reveals these findings. Radiologists should also carefully evaluate follow-up images in PBM patients even years after prophylactic surgery because residual bile ducts remain at risk for cancer.©RSNA, 2020.

Quantitative and Qualitative Evaluation of Convolutional Neural Networks with a Deeper U-Net for Sparse-View Computed Tomography Reconstruction.

RATIONALE AND OBJECTIVES: To evaluate the utility of a convolutional neural network (CNN) with an increased number of contracting and expanding paths of U-net for sparse-view CT reconstruction. MATERIALS AND METHODS: This study used 60 anonymized chest CT cases from a public database called "The Cancer Imaging Archive". Eight thousand images from 40 cases were used for training. Eight hundred and 80 images from another 20 cases were used for quantitative and qualitative evaluation, respectively. Sparse-view CT images subsampled by a factor of 20 were simulated, and two CNNs were trained to create denoised images from the sparse-view CT. A CNN based on U-net with residual learning with four contracting and expanding paths (the preceding CNN) was compared with another CNN with eight contracting and expanding paths (the proposed CNN) both quantitatively (peak signal to noise ratio, structural similarity index), and qualitatively (the scores given by two radiologists for anatomical visibility, artifact and noise, and overall image quality) using the Wilcoxon signed-rank test. Nodule and emphysema appearance were also evaluated qualitatively. RESULTS: The proposed CNN was significantly better than the preceding CNN both quantitatively and qualitatively (overall image quality interquartile range, 3.0-3.5 versus 1.0-1.0 reported from the preceding CNN; p < 0.001). However, only 2 of 22 cases used for emphysematous evaluation (2 CNNs for every 11 cases with emphysema) had an average score of ≥ 2 (on a 3 point scale). CONCLUSION: Increasing contracting and expanding paths may be useful for sparse-view CT reconstruction with CNN. However, poor reproducibility of emphysema appearance should also be noted.

Portal Vein Embolization: Radiological Findings Predicting Future Liver Remnant Hypertrophy.

OBJECTIVE. The purpose of this article is to evaluate the radiologic findings predicting the future liver remnant hypertrophy ratio after portal vein embolization of the right branch. MATERIALS AND METHODS. The associations between the radiologic findings and the future liver remnant hypertrophy ratio for 79 patients who underwent portal vein embolization of the right branch between July 2007 and April 2017 were retrospectively analyzed. Multiple linear regression was performed to adjust for potential confounders, and the volume ratio of the right lobe anterior segment, number of proximal small branches from the right anterior and posterior portal veins, transient hepatic parenchymal enhancement, portal vein invasion, and variants of main portal vein anatomy were evaluated. The potential confounders were age, ratio of future liver remnant hypertrophy to total liver volume, indocyanine green clearance rate, maximum serum total bilirubin before portal vein embolization, and history of chemotherapy. RESULTS. Statistically significant associations were found between the future liver remnant hypertrophy ratio and the number of proximal small branches from the right anterior and posterior portal veins (p < 0.001), transient hepatic parenchymal enhancement (p < 0.001), portal vein invasion (p = 0.017), and variants of main portal vein anatomy (p = 0.048). The mean future liver remnant hypertrophy rate was 51.0% (n = 16) in patients without the radiologic findings showing statistically significant differences, and 25.8% (n = 63) in patients with at least one significant finding. CONCLUSION. When added to previously reported factors, the radiologic findings identified can help determine the indications for portal vein embolization and novel strategies for major hepatectomy.

Left Gastric Vein Visualization with Hepatopetal Flow Information in Healthy Subjects Using Non-Contrast-Enhanced Magnetic Resonance Angiography with Balanced Steady-State Free-Precession Sequence and Time-Spatial Labeling Inversion Pulse.

Objective: To selectively visualize the left gastric vein (LGV) with hepatopetal flow information by non-contrast-enhanced magnetic resonance angiography under a hypothesis that change in the LGV flow direction can predict the development of esophageal varices; and to optimize the acquisition protocol in healthy subjects. Materials and Methods: Respiratory-gated three-dimensional balanced steady-state free-precession scans were conducted on 31 healthy subjects using two methods (A and B) for visualizing the LGV with hepatopetal flow. In method A, two time-spatial labeling inversion pulses (Time-SLIP) were placed on the whole abdomen and the area from the gastric fornix to the upper body, excluding the LGV area. In method B, nonselective inversion recovery pulse was used and one Time-SLIP was placed on the esophagogastric junction. The detectability and consistency of LGV were evaluated using the two methods and ultrasonography (US). Results: Left gastric veins by method A, B, and US were detected in 30 (97%), 24 (77%), and 23 (74%) subjects, respectively. LGV flow by US was hepatopetal in 22 subjects and stagnant in one subject. All hepatopetal LGVs by US coincided with the visualized vessels in both methods. One subject with non-visualized LGV in method A showed stagnant LGV by US. Conclusion: Hepatopetal LGV could be selectively visualized by method A in healthy subjects.

Non-contrast-enhanced 3D MR portography within a breath-hold using compressed sensing acceleration: A prospective noninferiority study.

PURPOSE: To evaluate images of non-contrast-enhanced 3D MR portography within a breath-hold (BH) using compressed sensing (CS) compared to standard respiratory-triggered (RT) sequences. MATERIALS AND METHODS: Fifty-nine healthy volunteers underwent MR portography using two sequences of balanced steady-state free-precession (bSSFP) with time-spatial labeling inversion pulses (Time-SLIP): BH bSSFP-CS and RT bSSFP. Two radiologists independently scored the diagnostic acceptability to delineate the portal branches (MPV: main portal vein; RPV: right portal vein; LPV: left portal vein; RPPV: right posterior portal vein; and P4 and P8: portal branch of segment 4 and segment 8, respectively) and the overall image quality on a four-point scale. We assessed noninferiority of BH bSSFP-CS to RT bSSFP. For quantitative analysis, vessel-to-liver contrast (Cv-l) was calculated in MPV, RPV and LPV. RESULTS: BH bSSFP sequence was successfully performed with a 30-second acquisition time. The diagnostic acceptability scores of BH bSSFP-CS compared with RT bSSFP were statistically noninferior: MPV (95% CI for score difference of Reader 1 and Reader 2, respectively: [-0.16, 0.06], [-0.05, 0.02]), RPV ([-0.00, 0.11], [-0.01, 0.08]), LPV ([-0.03, 0.10], [-0.10, 0.03]), RPPV ([-0.03, 0.10], [-0.05, 0.05]), P4 ([-0.13, 0.34], [-0.28, 0.21]) and P8 ([-0.21, 0.11], [-0.25, -0.02]). However, the overall image quality of BH bSSFP-CS did not show noninferiority ([-0.61, -0.24], [-0.54, -0.17]). Cv-l values were significantly lower in BH bSSFP-CS (P<0.001). CONCLUSION: CS enabled non-contrast-enhanced 3D bSSFP MR portography to be performed within a BH while maintaining noninferior diagnostic acceptability compared to standard RT bSSFP MR portography.

Non-contrast-enhanced magnetic resonance venography using magnetization-prepared rapid gradient-echo (MPRAGE) in the preoperative evaluation of living liver donor candidates: Comparison with conventional computed tomography venography.

OBJECTIVE: To compare the diagnostic performance of non-contrast-enhanced magnetic resonance venography using magnetization-prepared rapid gradient-echo (MPRAGE-MRV) and conventional computed tomography venography (CTV) in preoperative evaluation of venous tributaries for living donor liver transplantation. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained for this prospective study of 73 donor candidates. Of these, 23 underwent right-sided graft hepatectomy without middle hepatic vein. One or more tributaries, other than the right hepatic vein, were reconstructed for 20 of the 23 grafts. For these 20 grafts, the number and location of the tributaries requiring reconstruction were evaluated based on venography, and diagnostic performance was analyzed using surgical records as a reference standard. For each candidate, the number of small tributaries directly joining the inferior vena cava was counted in each venographic image; a paired-sample t-test was used to assess differences. The severity of respiratory artifacts in MPRAGE-MRV was qualitatively evaluated, and compared using Wilcoxon's rank-sum test. RESULTS: All reconstructed venous tributaries were prospectively identified using both methods. MPRAGE-MRV tended to provide a greater number of small tributaries than conventional CTV (mean: 2; 95% CI: [1.66, 2.34], and 1.74; [1.44, 2.04], respectively), although the difference was not significant (P=0.10); MPRAGE-MRV was superior or equal to CTV in 52 subjects (71.2%), and inferior in 21 subjects (28.8%). Respiratory artifacts were significantly less severe in the former subjects (P<0.0001). CONCLUSIONS: MPRAGE-MRV has the potential to replace conventional CTV in the preoperative evaluation of living liver donor candidates.

Portal vein branching order helps in the recognition of anomalous right-sided round ligament: common features and variations in portal vein anatomy.

PURPOSE: This study aimed to evaluate the common features and variations of portal vein anatomy in right-sided round ligament (RSRL), which can help propose a method to detect and diagnose this anomaly. METHODS: In this retrospective study of 14 patients with RSRL, the branching order of the portal tree was analyzed, with special focus on the relationship between the dorsal branch of the right anterior segmental portal vein (PA-D) and the lateral segmental portal vein (PLL), to determine the common features. The configuration of the portal vein from the main portal trunk to the right umbilical portion (RUP), the inclination of the RUP, and the number and thickness of the ramifications branching from the right anterior segmental portal vein (PA) were evaluated for variations. RESULTS: In all subjects, the diverging point of the PA-D was constantly distal to that of the PLL. The portal vein configuration was I- and Z-shaped in nine and five subjects, respectively. The RUP was tilted to the right in all subjects. In Z-shaped subjects, the portal trunk between the branching point of the right posterior segmental portal vein and that of the PLL was tilted to the left in one subject and was almost parallel to the vertical plane in four subjects. Multiple ramifications were radially distributed from the PA in eight subjects, whereas one predominant PA-D branched from the PA in six subjects. CONCLUSIONS: Based on the diverging points of the PA-D and PLL, we proposed a three-step method for the detection and diagnosis of RSRL.

Selective visualization of pelvic splanchnic nerve and pelvic plexus using readout-segmented echo-planar diffusion-weighted magnetic resonance neurography: A preliminary study in healthy male volunteers.

PURPOSE: To evaluate the potential of readout-segmented echo-planar diffusion-weighted magnetic resonance neurography (RS-EPI DW-MRN) for the selective visualization of pelvic splanchnic nerve and pelvic plexus in healthy male volunteers. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. RS-EPI DW-MRN images were acquired from thirteen healthy male volunteers aged 25-48 years between September 2013 and December 2013. For RS-EPI DW-MRN, the following parameters were used: spatial resolution, 1.1×1.1×2.5mm; b-value, 250s/mm2; number of readout-segments, seven; and acquisition time, 7min 45s. For qualitative assessment, two abdominal radiologists independently evaluated the visibility of the pelvic splanchnic nerves and pelvic plexuses bilaterally in each subject on oblique coronal thin-slab 10-mm-thick maximum intensity projection images and scored it with a 4-point grading scale (excellent, good, fair, poor). Both readers scored twice at 6-month intervals. Inter-observer and intra-observer variability were evaluated using Cohen's quadratically weighted κ statistics. Image artifact level was scored on a 4-point grading scale by other two abdominal radiologists in order to evaluate the correlation between the nerve visibility and the severity of imaging artifacts using the Spearman's correlation coefficient. RESULTS: Qualitative grading showed the following success rate (number of nerves qualitatively scored as excellent or good divided by total number of nerves): reader 1 (first set), 73% (19/26); reader 2 (first set), 77% (20/26); reader 1 (second set), 81% (21/26); and reader 2 (second set), 77% (20/26). Inter-observer agreement between readers 1 and 2 was excellent: κ=0.947 (first set) and 0.845 (second set). Intra-observer agreement was also excellent: κ=0.810 (reader 1) and 0.946 (reader 2). The visibility of pelvic splanchnic nerve and pelvic plexus showed a moderate correlation with the image artifact level (ρ=0.54, p=0.004). CONCLUSION: This study demonstrated that RS-EPI DW-MRN is a promising approach for selectively visualizing the pelvic splanchnic nerve and pelvic plexus.

Upside-Down and Inside-Out Signs in Uterine Inversion.

Uterine inversion is a rare condition that is accompanied by massive hemorrhaging and shock, resulting in a maternal emergency. The diagnosis of uterine inversion is often difficult due to massive postpartum hemorrhaging. Ultrasonography is useful for the diagnosis in such conditions, but we do not often encounter typical ultrasonographic images in uterine inversion because it occurs rarely. In the present case report of uterine inversion, we demonstrate the typical ultrasonographic findings of uterine inversion.

Usefulness of breath-hold inversion recovery-prepared T1-weighted two-dimensional gradient echo sequence for detection of hepatocellular carcinoma in Gd-EOB-DTPA-enhanced MR imaging.

The aim is to evaluate the diagnostic performance and the added value of breath-hold inversion recovery-prepared T1-weighted two-dimensional gradient echo (IR-2D-GRE) sequence for detection of hepatocellular carcinoma (HCC) in patients with insufficient liver parenchymal enhancement during the hepatobiliary phase (HBP) of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). Seventeen patients with a quantitative liver-to-spleen contrast ratio of ≤1.5 on HBP images and 36 HCCs were included. Liver-to-lesion contrast ratios on HBP images obtained with IR-2D-GRE sequence were significantly higher than those with three-dimensional gradient echo sequence. The addition of IR-2D-GRE sequence during HBP of Gd-EOB-DTPA-enhanced MRI yielded higher diagnostic accuracy and improved sensitivity.

Additional benefit of computed diffusion-weighted imaging for detection of hepatic metastases at 1.5T.

The aim is to investigate the added value of computed diffusion-weighted magnetic resonance imaging (DWI) at 1.5T in detecting hepatic metastases. Fifty-six patients with a total of 100 hepatic metastases were included. Computed DWI was synthesized from lower b values. Diagnostic performance was evaluated by receiver operating characteristic (ROC) curve analysis. The sensitivity was calculated and analyzed. The area under the ROC curve of the computed DWI was larger than that of acquired DWI. Both readers detected significantly more hepatic metastases with combined acquired DWI/computed DWI. Combined use of computed DWI with acquired DWI helped to provide higher sensitivity at 1.5T.

Decreased proteasomal function accelerates cigarette smoke-induced pulmonary emphysema in mice.

Chronic obstructive pulmonary disease (COPD) is a disease common in elderly people, characterized by progressive destruction of lung parenchyma and chronic inflammation of the airways. The pathogenesis of COPD remains unclear, but recent studies suggest that oxidative stress-induced apoptosis in alveolar cells contributes to emphysematous lung destruction. The proteasome is a multicatalytic enzyme complex that plays a critical role in proteostasis by rapidly destroying misfolded and modified proteins generated by oxidative and other stresses. Proteasome activity decreases with aging in many organs including lungs, and an age-related decline in proteasomal function has been implicated in various age-related pathologies. However, the role of the proteasome system in the pathogenesis of COPD has not been investigated. Recently, we have established a transgenic (Tg) mouse model with decreased proteasomal chymotrypsin-like activity, showing age-related phenotypes. Using this model, we demonstrate here that decreased proteasomal function accelerates cigarette smoke (CS)-induced pulmonary emphysema. CS-exposed Tg mice showed remarkable airspace enlargement and increased foci of inflammation compared with wild-type controls. Importantly, apoptotic cells were found in the alveolar walls of the affected lungs. Impaired proteasomal activity also enhanced apoptosis in cigarette smoke extract (CSE)-exposed fibroblastic cells derived from mice and humans in vitro. Notably, aggresome formation and prominent nuclear translocation of apoptosis-inducing factor were observed in CSE-exposed fibroblastic cells isolated from Tg mice. Collective evidence suggests that CS exposure and impaired proteasomal activity coordinately enhance apoptotic cell death in the alveolar walls that may be involved in the development and progression of emphysema in susceptible individuals such as the elderly.

Two adult cases of extralobar pulmonary sequestration: A non-complicated case and a necrotic case with torsion.

BACKGROUND: This case report describes two cases of extralobar pulmonary sequestration in adults with and without torsion/necrosis. CASE REPORTS: Non-complicated extralobar pulmonary sequestration was found incidentally in a 50-year-old asymptomatic woman (Case 1), diagnosed with the presence of a branching structure in a mass lesion and blood supply from the right inferior phrenic artery. Another case of a 38-year-old woman presented with a sudden onset of back pain caused by extralobar pulmonary sequestration with torsion/necrosis (Case 2). A 4-cm fusiform mass in the paravertebral region showed enhancement in the peripheral rim only, and no feeding artery. These were the same as it had been reported typical findings in extralobar pulmonary sequestration with necrosis. On magnetic resonance imaging, the masses in both cases showed inhomogeneous low signal and branching high signal on T2-weighted images. That was characteristic for a stroma without dilated alveoli as a solid part and dilated alveoli as fluid regions. CONCLUSIONS: By comparing those two cases, we came to a conclusion that only T2-weighted imaging reflects the native structure, even after infarction. Although differentiation from a cystic tumor with hemorrhage or infection can be problematic, inhomogeneous low signal and branching high signal on T2-weighted images may help us distinguish extralobar pulmonary sequestration from other cystic lesions.

Decreased proteasomal activity causes age-related phenotypes and promotes the development of metabolic abnormalities.

The proteasome is a multicatalytic enzyme complex responsible for the degradation of both normal and damaged proteins. An age-related decline in proteasomal activity has been implicated in various age-related pathologies. The relevance of decreased proteasomal activity to aging and age-related diseases remains unclear, however, because suitable animal models are not available. In the present study, we established a transgenic (Tg) mouse model with decreased proteasomal chymotrypsin-like activity. Tg mice exhibited a shortened life span and developed age-related phenotypes. In Tg mice, polyubiquitinated and oxidized proteins accumulated, and the expression levels of cellular proteins such as Bcl-xL and RNase L were altered. When Tg mice were fed a high-fat diet, they developed more pronounced obesity and hepatic steatosis than did wild-type mice. Consistent with its role in lipid droplet formation, the expression of adipose differentiation-related protein (ADRP) was elevated in the livers of Tg mice. Of note, obesity and hepatic steatosis induced by a high-fat diet were more pronounced in aged than in young wild-type mice, and aged wild-type mice had elevated levels of ADRP, suggesting that the metabolic abnormalities present in Tg mice mimic those in aged mice. Our results provide the first in vivo evidence that decreased proteasomal chymotrypsin-like activity affects longevity and aggravates age-related metabolic disorders, such as obesity and hepatic steatosis.