Correlation between main pancreatic duct diameter measurements: Special pancreatic ultrasonography versus magnetic resonance cholangiopancreatography.

Main pancreatic duct (MPD) dilatation is reported to be a risk factor for pancreatic cancer (PC). Although magnetic resonance cholangiopancreatography (MRCP) and ultrasonographic modalities are valuable for monitoring the pancreas, there is limited information on the efficacy of different imaging modalities in measuring MPD diameter. To improve pancreatic imaging, we developed a specialized ultrasound approach focusing on the pancreas (special pancreatic US). We aimed to examine the correlation between MPD diameter measurements using special pancreatic US versus MRCP. We retrospectively reviewed the clinical data of patients with MPD dilation (≥2.5 mm) via special pancreatic US used for screening at our institution between January 2020 and October 2022 and included patients who underwent magnetic resonance imaging 2 months before and after pancreatic US. The MPD diameter on MRCP was measured at the pancreatic locus, where the maximum MPD diameter was obtained on special pancreatic US. This study included 96 patients, with a median interval of 8.5 days between the date of special pancreatic US and the date of undergoing MRCP. MPD dilatation and/or pancreatic cysts were diagnosed in 86 patients, PC in 5 patients, and other diseases in 5 patients. The median MPD diameter, measured using special pancreatic US, was 3.4 mm (interquartile range: 2.9-4.9 mm), whereas it was 3.5 mm using MRCP (interquartile range: 2.8-4.5 mm). There were strong positive correlations between MPD diameter measured on special pancreatic US and that measured on MRCP (R = 0.925, P < .001). This study revealed strong positive correlations between the MPD diameter measurements using special pancreatic US and MRCP. MPD diameter measurements from each imaging method can be helpful during follow-up in individuals at a high risk of PC.

Calyceal Diverticulum Found Incidentally on 18 F-FDG PET/CT Imaging.

ABSTRACT: A 69-year-old man with pancreatic cancer underwent 18 F-FDG PET/CT examination for tumor staging. The PET images showed a focal mass-like FDG accumulation in the left kidney mimicking malignancy, whereas simultaneous CT and fused PET/CT images suggested a cystic lesion. On subsequent MR examination, the lesion appeared cystic on T2-weighted, contrast-enhanced arterial phase, and contrast-enhanced venous phase images. In addition, excretory phase images showed filling contrast medium to the cystic cavity, leading to a diagnosis of calyceal diverticulum. This report suggests that the possibility of a calyceal diverticulum should be considered in cases with focal FDG accumulation in renal cystic lesions.

Nonbrain metastases seen on magnetic resonance imaging during metastatic brain tumor screening.

Although metastases found during head magnetic resonance imaging (MRI) are not limited to metastatic brain tumors, the MRI is a very common method for "brain metastasis screening," a modality that is being increasingly performed. In this review, we describe MRI findings of nonbrain metastases and discuss ways to avoid missing these lesions. Metastatic cranial bone tumors are among the most common nonbrain metastatic lesions found on head MRI, followed by leptomeningeal carcinomatosis. The other less-frequent metastatic lesions include those in the ventricle/choroid plexus, the pituitary gland and stalk, and the pineal gland. Metastases in the head and neck area, as well as cranial and intracranial lesions, should be carefully evaluated. Furthermore, direct geographical invasion, perineural spread, and double cancers should also be considered. While it is important to recognize these metastatic lesions on MRI, because they may necessitate a change in treatment strategy that could lead to an improvement in prognosis due to early introduction of therapy, nonbrain lesions should also be given greater attention, given the increasing survival of patients with cancer and advances in MRI technology, such as contrast-enhanced-3D T1-weighted imaging.

Whole-body MRI: detecting bone metastases from prostate cancer.

Whole-body magnetic resonance imaging (WB-MRI) is currently used worldwide for detecting bone metastases from prostate cancer. The 5-year survival rate for prostate cancer is > 95%. However, an increase in survival time may increase the incidence of bone metastasis. Therefore, detecting bone metastases is of great clinical interest. Bone metastases are commonly located in the spine, pelvis, shoulder, and distal femur. Bone metastases from prostate cancer are well-known representatives of osteoblastic metastases. However, other types of bone metastases, such as mixed or inter-trabecular type, have also been detected using MRI. MRI does not involve radiation exposure and has good sensitivity and specificity for detecting bone metastases. WB-MRI has undergone gradual developments since the last century, and in 2004, Takahara et al., developed diffusion-weighted Imaging (DWI) with background body signal suppression (DWIBS). Since then, WB-MRI, including DWI, has continued to play an important role in detecting bone metastases and monitoring therapeutic effects. An imaging protocol that allows complete examination within approximately 30 min has been established. This review focuses on WB-MRI standardization and the automatic calculation of tumor total diffusion volume (tDV) and mean apparent diffusion coefficient (ADC) value. In the future, artificial intelligence (AI) will enable shorter imaging times and easier automatic segmentation.

Hypervascular hepatocellular carcinomas: detection with gadoxetate disodium-enhanced MR imaging and multiphasic multidetector CT.

OBJECTIVES: To retrospectively compare the accuracy of detection of hypervascular hepatocellular carcinoma (HCC) by multiphasic multidetector CT and by gadoxetate disodium-enhanced MR imaging. METHODS: After ethical approval, we analysed a total of 73 hypervascular HCC lesions from 31 patients suspected of having HCC, who underwent both gadoxetate disodium-enhanced MR imaging and multiphasic multidetector CT. Five blinded observers independently reviewed CT images, as well as dynamic MR images alone and combined with hepatobiliary phase MR images. Diagnostic accuracy (Az values), sensitivities and positive predictive values were compared by using the Scheffe post hoc test. RESULTS: The mean Az value for dynamic and hepatobiliary phase MR combined (0.81) or dynamic MR images alone (0.78) was significantly higher than that for CT images (0.67, P < 0.001, 0.005, respectively). The mean sensitivity of the combined MR images (0.67) was significantly higher than that of dynamic MR alone (0.52, P < 0.05) or CT images (0.44, P < 0.05). The mean positive predictive values were 0.96, 0.95 and 0.94, for CT, dynamic MR alone and combined MR images, respectively. CONCLUSIONS: Compared with multiphasic multidetector CT, gadoxetate disodium-enhanced MR imaging combining dynamic and hepatobiliary phase images results in significantly improved sensitivity and diagnostic accuracy for detection of hypervascular HCC. KEY POINTS: Gadoxetate disodium is a new liver-specific MR imaging contrast agent. Gadoxetate disodium-enhanced MRI helps the assessment of patients with liver disease. It showed high diagnostic accuracy for the detection of hepatocellular carcinoma.

Correlations between aorto-popliteal bolus transit speed and aortic and popliteal bolus transit time during CT angiography of aortoiliac and lower extremity arteries.

PURPOSE: The purpose of this study was to investigate correlations between the aorto-popliteal bolus transit speed and aortic and popliteal bolus transit time in order to evaluate the possibility for prediction of bolus transit speed by single test injection technique. MATERIALS AND METHODS: Approval was obtained from our institutional review board for this study, which included 42 patients, from all of whom written informed consent was obtained. Low-dose serial CT scanning after injection of 12 ml contrast material (300 mg/ml) at a rate of 3 ml/s followed by saline flush was performed twice, first at the level of the upper abdomen and second at the level of the knee joint. The times needed to reach peak enhancement of the upper abdominal aorta (T-aorta) and bilateral popliteal arteries (T-popliteal) were obtained, and aorto-popliteal bolus transit speeds between the abdominal aorta and popliteal arteries were calculated. ABI was recorded for the bilateral feet. The Pearson's product-moment correlation coefficient was used to investigate the correlation between the bolus transit speed and T-aorta, T-popliteal, ABI, and patient age. RESULT: The respective correlation coefficients for bolus transit speed on the one hand and T-aorta, T-popliteal, ABI, patient age on the other were -0.50, -0.84, 0.36, and -0.52. CONCLUSION: The time to peak enhancement for popliteal arteries showed the strongest correlation with aorto-popliteal bolus transit speeds, and was considered to be the most accurate predictor for aorto-popliteal bolus transit speeds.

Comparative study of the diagnostic ability of magnetic resonance imaging and multidetector row computed tomography for anomalous pancreaticobiliary ductal junction.

OBJECTIVE: To compare the diagnostic performance of magnetic resonance (MR) imaging and multidetector row computed tomography (MDCT) for an anomalous pancreaticobiliary ductal junction (PBJ). METHODS: This study included 26 patients who underwent MR imaging, MDCT, and endoscopic retrograde cholangiopancreatography. Seventeen of the patients were diagnosed by endoscopic retrograde cholangiopancreatography as having an anomalous PBJ. Three radiologists independently reviewed MR images alone, contrast-enhanced CT images alone, and MR images and CT images combined. Receiver operating characteristic curve analysis was used to compare diagnostic capabilities. RESULTS: The mean area under the receiver operating characteristic curve (Az [95% confidence interval]) was 0.75 (0.73-0.77) for MR imaging alone, 0.79 (0.70-0.89) for CT alone, and 0.84 (0.82-0.86) for the 2 modalities combined. Only between the combination and MR imaging alone was there significant difference in Az value (P < 0.05). CONCLUSIONS: The diagnostic performance of MR imaging and MDCT was equivalent for an anomalous PBJ. The addition of MDCT to MR imaging improved the diagnostic performance.

MR cholangiopancreatography at 3.0 T: intraindividual comparative study with MR cholangiopancreatography at 1.5 T for clinical patients.

OBJECTIVES: To prospectively evaluate the image quality and diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) at 3.0 T compared with that at 1.5 T used for patients. MATERIALS AND METHODS: This study was approved by our institutional review board, and informed consent was obtained from all patients. Three-dimensional MRCP with both a 1.5-T system and a 3.0-T system was administered to 33 consecutive patients suspected of having biliary and/or pancreatic diseases. For 3-dimensional MRCP imaging, a respiratory-triggered Fast Recovery Fast Spin Echo sequence with the parallel imaging technique was used for both systems. The spatial resolution at 1.5 T was matched to that at 3.0 T, and matrix size was 512 x 160, field of view (FOV) 36 x 36 cm, slice thickness 2 mm, and the number of slices ranged from 44 to 54. Repetition time varied according to the patients' respiratory cycles, which ranged from 3000 milliseconds to 6000 milliseconds, and effective echo time, ranging from 391 milliseconds to 482 milliseconds, was automatically determined by the systems. Contrast of imaging of the common bile duct versus that of the periductal tissue was quantitatively evaluated. The image quality for homogeneity of signal intensity, image noise, susceptibility artifacts, and overall imaging quality and diagnostic accuracy for stenoses of bile and main pancreatic ducts and for pancreatic cystic lesions were qualitatively evaluated. The results for 1.5- and 3.0-T were then compared statistically, by using the paired t test for quantitative evaluation of contrast between the common bile duct and the periductal tissue, the Wilcoxon signed rank test for visual evaluation of the image quality, and the McNemar chi2 test for evaluation of sensitivity and specificity for diagnostic purposes. A P value of less than 0.05 was considered to indicate a statistically significant difference. RESULTS: Contrast of the common bile duct versus that of the periductal tissue at 3.0 T was superior to that at 1.5 T (P < 0.001). In the visual evaluation, image quality at 3.0 T was superior to that at 1.5 T for evaluation of image noise (P < 0.001), overall image quality (P < 0.001), and delineation of intrahepatic bile ducts (P < 0.01) and the main pancreatic duct (P < 0.05), whereas there were no significant differences in homogeneity of signal intensity and in susceptibility artifacts. The diagnostic accuracy for 3.0 T was approximately equivalent to that for 1.5 T. CONCLUSION: Our results for patients with biliary and pancreatic diseases demonstrate a marked improvement in contrast of the common bile duct versus that of the periductal tissue and image quality including image noise at 3.0 T compared by 1.5 T when identical spatial resolution configuration were used. The results suggest that 3.0 T may allow higher spatial resolution and offer promise for improved diagnosis in MRCP, although further investigations using optimize scan parameters will be needed before its full potential can be achieved.

MR imaging of endometrial carcinoma for preoperative staging at 3.0 T: comparison with imaging at 1.5 T.

PURPOSE: To prospectively compare magnetic resonance imaging (MRI) at 3.0 T and 1.5 T in the same patients for preoperative evaluation of endometrial carcinoma. MATERIALS AND METHODS: Thirty consecutive patients with endometrial carcinoma underwent MRI at both 3.0 T and 1.5 T as well as surgery. Quantitative and qualitative analyses were performed. Two radiologists independently evaluated images. MR findings were compared with surgicopathologic findings. RESULTS: Image homogeneity of T2-weighted images at 3.0 T was significantly inferior to that at 1.5 T (P = 0.007). The scores of image homogeneity and susceptibility artifacts were not significantly different between 3.0 T gadolinium-enhanced imaging and 1.5 T imaging (P = 0.09 and 0.36). Kappa statistics showed good interobserver agreement between the two radiologists for local-regional staging on T2-weighted images (kappa>0.6). The area under the receiver operating characteristic curve (Az) values for T2-weighted imaging in terms of myometrial invasion, cervical invasion, and lymph node metastases were 0.88 (3.0 T) versus 0.91 (1.5 T), 0.84 versus 0.83, and 0.94 versus 0.95 for reader 1, respectively. There were no significant differences between imaging at 3.0 T and at 1.5 T in Az values for either reader (P > 0.35). CONCLUSION: 3.0 T MRI is an equivalent imaging modality to 1.5 T imaging for presurgical evaluation of endometrial carcinoma, although not significantly superior to 1.5 T imaging.

64-slice multidetector row computed tomographic angiography of aortoiliac and lower extremity arteries: efficacy of test injection using a monitoring scan at knee level.

OBJECTIVES: To evaluate the efficacy of test injection technique using a monitoring scan at knee level for 64-slice multidetector row computed tomographic (MDCT) angiography of the abdominal and lower extremity arteries. METHODS: The test injection technique using low-dose serial CT scan at knee level was performed for 58 patients. Time elapsed from contrast material injection to peak enhancement for the popliteal arteries was applied to scan delay for CT angiography. 64-Slice MDCT angiography of the abdominal and lower extremity arteries obtained with a table speed of 137.5 mm/s was evaluated. RESULTS: The time to peak enhancement was unavailable in 2 cases. CT angiographic images were of good quality in 54 cases, whereas prominent enhancement of abdominal veins was observed in 2 cases. CONCLUSIONS: The test injection using a monitoring scan at knee level was found to be useful for 64-slice MDCT angiography of the abdominal and lower extremity arteries.

Angiographic evaluation of hepatic arterial damage after transarterial chemoembolization for hepatocellular carcinoma.

PURPOSE: The aim of this study was to assess the incidence, degree, and predictors of hepatic arterial damage (HAD) after transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A total of 33 patients with unresectable HCC underwent TACE alone using a mixture of iodized oil, epirubicin, and gelatin sponge. A follow-up angiogram was available for 76 of 109 sessions, and HAD was evaluated at each subsegment of the hepatic artery using a three-grade scale (1, no or slight wall irregularity; 2, overt stenosis; 3, occlusion). Grades 2 and 3 were considered to indicate significant HAD. The predictors of HAD were analyzed by multivariate analysis. RESULTS: A total of 161 hepatic arteries were embolized from the lobar (n = 43), segmental (n = 40), subsegmental (n = 72), or more distal (n = 6) level. The follow-up period between the initial and last sessions ranged from 70 to 1505 days (median 497 days). Significant HAD occurred in 37 of 231 subsegmental hepatic arteries (16%) and in 16 of 33 patients (48%). The accumulated dose of epirubicin per artery (P = 0.001) and Child-Pugh score (P < 0.001) were significant predictors. CONCLUSION: TACE is more likely to induce HAD in cirrhotic patients with impaired liver function and when a high dose of the chemotherapeutic agent was used.