Refractory splenic bleeding from splenic angiosarcoma: A case report and literature review.

INTRODUCTION AND IMPORTANCE: Atraumatic splenic rupture (ASR) is a rare state that accounts for only <1 % of splenic ruptures. One of the causes of ASR is splenic neoplasm such as angiosarcoma. The treatment strategy for ASR is still unclear given the small number of cases reported in detail. CASE PRESENTATION: A 75-year-old woman presenting with abdominal pain with shock was referred to our hospital. Emergency computed tomography revealed splenic rupture, and hemodynamic stabilization was obtained by emergent vascular embolization. Rebleeding occurred 27 days after the initial treatment, and splenectomy was performed. Pathologically, ASR was diagnosed as caused by splenic angiosarcoma. CLINICAL DISCUSSION: ASR is a very rare disease. The etiology of ASR has been reported as neoplastic, infectious, and so on. The treatment for ASR should be decided considering the etiology of ASR, hemodynamic stability, volume of blood transfusion, patient status, severity of the splenic injury, and volume of intraperitoneal bleeding. CONCLUSIONS: We experienced a very rare case of ASR, in which diagnosis was challenging and the timing of surgery was difficult to determine. When splenic rupture has an atraumatic cause, splenectomy should be considered because of the possibility of malignancy.

Synchronous solid pseudopapillary neoplasm and invasive ductal carcinoma of the pancreas: a case report.

BACKGROUND: Solid pseudopapillary neoplasm (SPN) of the pancreas is an extremely rare neoplasm with a favorable prognosis. On the other hand, pancreatic invasive ductal carcinoma (IDC) is known to be an aggressive malignancy. To the best of our knowledge, there is no report of SPN combined with IDC of the pancreas. CASE PRESENTATION: A 66-year-old woman presented with abnormal genital bleeding and was diagnosed with inoperable cervical cancer. During computed tomography for cancer staging, the patient was incidentally diagnosed with pancreatic cancer. After radiation therapy for the cervical cancer, distal pancreatectomy with D2 lymph node dissection was performed. A postoperative pathological examination revealed SPN with ossification and well-differentiated IDC in the pancreatic body. On immunohistochemical staining, SPN tumor cells showed positive ß-catenin and CD10 staining, whereas IDC cells were negative for both. The tumor boundaries were clear. Accordingly, the final pathological diagnosis was synchronous SPN and IDC of the pancreas. Moreover, pathological findings such as the ossification and small number of SPN cells suggested that SPN may have existed long before IDC initiation. CONCLUSIONS: Here, we report the first case of SPN combined with IDC of the pancreas. They may occur independently, and the long-term presence of SPN may lead to the development of IDC.

Hyperintense Liver Masses at Hepatobiliary Phase Gadoxetic Acid-enhanced MRI: Imaging Appearances and Clinical Importance.

Gadoxetic acid, a hepatobiliary-specific contrast medium used for MRI, is becoming increasingly important in the detection and characterization of hepatic mass lesions. This medium is taken up by functioning hepatocytes, and the liver parenchyma is strongly enhanced in the hepatobiliary phase (HBP), during which hepatic mass lesions without functioning hepatocytes commonly show hypointensity. However, some hepatic mass lesions show hyperintensity in the HBP. Focal nodular hyperplasia (FNH) and FNH-like lesions show hyperintensity in the HBP owing to the uptake of gadoxetic acid by hyperplastic normal hepatocytes. The tumor cells of some types of hepatocellular adenoma (eg, ß-catenin-activated type, inflammatory type) and hepatocellular carcinoma (eg, green hepatoma) can show uptake of gadoxetic acid. Retention of gadoxetic acid in the extracellular space can cause hyperintensity of fibrotic tumors or hemangiomas during the HBP owing to the extracellular contrast agent characteristics of gadoxetic acid. During the HBP, peritumoral retention is observed in some tumors, such as hepatocellular carcinomas, gastrointestinal stromal tumors, and neuroendocrine tumors. Gadoxetic acid is excreted into the bile; therefore, biliary tract enhancement can be observed in the cystic components of intraductal papillary neoplasms of the bile duct. Intratumoral bile ducts can be observed in malignant lymphomas. Knowledge of these specific mechanisms, which can cause hyperintensity during the HBP depending on the pathologic or molecular background, is important not only for precise imaging-based diagnoses but also for understanding the pathogenesis of hepatic mass lesions. ©RSNA, 2019 See discussion on this article by Lalwani.

Improved visualization of a fine intrahepatic biliary duct on drip infusion cholangiography-computed tomography: Impact of knowledge-based iterative model reconstruction.

AIM: The purpose of this study was to investigate the visualization of fine biliary ducts with knowledge-based iterative model reconstruction (IMR) in low-dose drip infusion computed tomography (CT) cholangiography (DIC-CT) as compared with filtered back projection (FBP) and hybrid iterative reconstruction (iDose4 ). METHODS: A total of 38 patients underwent DIC-CT for living donor liver transplantation. CT was performed approximately 20 min after the end of the infusion of meglumine iotroxate (100 mL). Images were reconstructed using FBP, iDose4 , and IMR, and 1-mm slice images at fixed window level and width were prepared for assessment. Two reviewers independently evaluated the quality of visualization of the fine biliary ducts of the caudate lobe (B1) using a 5-point scale. The visualization scores of three reconstructed images were compared using the Kruskal-Wallis test and Mann-Whitney U-test. RESULTS: For reviewer 1, the visualization score of IMR was significantly higher than that of FBP (P = 0.012), and tended to be higher than that of iDose4 (P = 0.078). For reviewer 2, the visualization score of IMR was significantly higher than those of both FBP and iDose4 (P < 0.01). CONCLUSIONS: IMR showed better visualization of B1 on DIC-CT than FBP or iDose4 . DIC-CT reconstructed with IMR may be useful to the anatomical grasp of biliary tracts in cases of hepatectomy.

Amide proton transfer imaging for differentiating benign ovarian cystic lesions: Potential of first time right.

PURPOSE: To investigate whether amide proton transfer (APT) imaging is useful to differentiate benign ovarian cystic lesions. MATERIALS AND METHODS: This prospective study enrolled a total of 19 lesions in 18 patients with benign ovarian cystic lesion: serous cystadenoma (SCA), n = 4; mucinous cystadenoma (MCA), n = 9; or functional cyst (FC), n = 6. APT imaging was performed with three different presaturation pulse durations: 0.5, 1.0 and 2.0 s. APT signal was defined as magnetization transfer ratio asymmetry at 3.5 ppm. The SI ratios of cyst to muscle calculated on T1- and T2-weighted images were defined as T1- and T2-ratios. Apparent diffusion coefficient (ADC) maps were also generated. We compared the three cystic lesion groups' APT signals, T1-ratio, T2-ratio, and ADC. RESULTS: When using 2.0 s of presaturation, the APT signals were 1.41 ±â€¯0.71% in SCA, 5.15 ±â€¯1.92% in MCA and 8.52 ±â€¯1.17% in FC. Significant differences were observed between SCA and MCA (p < .01) and MCA and FC (p < .05), as well as between SCA and FC (P <  .0001). When 1.0 s presaturation pulse was used, similar results were obtained. On the other hand, ADC value shows significance only between SCA (2.91±0.03×10-3 mm2/s) and MCA (2.59 ±â€¯0.49 × 10-3 mm2/s, p < .05). Further, there was no significant difference in the T1-ratio, T2-ratio among the three groups. CONCLUSIONS: APT imaging might be useful for the non-invasive diagnosis of benign ovarian cystic lesions. With the use of the longer presaturation pulse as possible, APT imaging may provide an early and correct diagnosis of ovarian cystic lesions without additional follow-up studies.

Superparamagnetic iron-oxide-enhanced diffusion-weighted magnetic resonance imaging for the diagnosis of intrapancreatic accessory spleen.

PURPOSE: To evaluate the diagnostic performance of superparamagnetic iron-oxide (SPIO)-enhanced diffusion-weighted image (DWI) for distinguishing an intrapancreatic accessory spleen from pancreatic tumors. MATERIALS AND METHODS: Twenty-six cases of intrapancreatic accessory spleen and nine cases of pancreatic tail tumors [neuroendocrine tumor (n = 8) and pancreatic adenocarcinoma (n = 1)] were analyzed. Two blind reviewers retrospectively reviewed the SPIO-enhanced magnetic resonance imaging (MRI) scans. The lesion visibility grades were compared and the diagnostic performance of SPIO-enhanced DWI was compared to those of SPIO-enhanced T2WI and T2*WI with the use of a receiver operating characteristic (ROC) analysis. RESULTS: The grade of lesion visibility was the highest on DWI [mean ± standard deviation (SD): 2.8 ± 0.3] followed by T2WI (2.3 ± 0.7, p < 0.001) and T2*WI (2.1 ± 0.7, p < 0.0001). Reviewers 1 and 2 correctly characterized the presence or absence of SPIO uptake in 34 of 35 cases (97.1%) on DWI, 24 (68.6%) and 25 (71.4%) cases on T2WI, respectively, and 16 (45.7%) and 17 (48.6%) cases on T2*WI. The area under the ROC curve (AUC) of DWI was 0.974 and 0.989 for reviewers 1 and 2, respectively. For Reviewer 1, the AUC of DWI was significantly higher than that of T2*WI (0.756, p < 0.01), although it was not significantly different from that of T2WI (0.868, p = 0.0857). For Reviewer 2, the AUC of DWI was significantly higher than those of T2WI (0.846, p < 0.05) and T2*WI (0.803, p < 0.01). CONCLUSION: The diagnostic performance of SPIO-enhanced DWI was better than those of SPIO-enhanced T2*WI and T2WI for the diagnosis of intrapancreatic accessory spleen.

Imaging features of undifferentiated carcinoma of the pancreas.

INTRODUCTION: The purpose of this retrospective study was to evaluate imaging features of undifferentiated carcinoma of the pancreas. METHODS: The study group included eight patients with surgically resected undifferentiated carcinoma of the pancreas. Multidetector-row computed tomography (MDCT, n = 8) and magnetic resonance imaging (MRI, n = 6) findings were retrospectively reviewed. RESULTS: On MDCT, all eight cases were hypovascular with upstream main pancreatic duct (MPD) dilatation, and only 1 showed exophytic growth. Five cases (62.5%) showed necrosis/cystic change, and calcification was observed in two cases (25%). Calcification reflected tumour osteoid components. On MRI, haemorrhage and hemosiderin were observed in 4 of 6 (66.7%) cases. In addition, tumour thrombus in the splenic vein (n = 1) and intraductal tumour growth in the MPD (n = 2) were pathologically identified, although imaging studies only revealed 1 of these latter cases. CONCLUSION: Undifferentiated carcinoma of the pancreas may present as a tumour with haemorrhagic necrosis. Coexistence of calcification, intraductal tumour growth in the MPD and tumour thrombus may support the imaging diagnosis of this entity.

Usefulness of a Pretreatment CT-Based Modified RENAL Nephrometry Score in Predicting Renal Function After Cryotherapy for T1a Renal Mass.

PURPOSE: We investigated the usefulness of the modified RENAL nephrometry (mRN) scoring system for predicting post-cryotherapy renal function in patients with T1a renal mass. PATIENTS AND METHODS: A total of 75 patients with a T1a renal mass were enrolled. The mRN score was determined based on the tumor size, the tumor's exophytic/endophytic properties, the tumor's nearness to the collecting system, and the anterior/posterior location of the kidney. The change in the estimated glomerular filtration rate (ΔeGFR) was calculated as follows: ΔeGFR = 100 × ([pretreatment eGFR - eGFR at 6 months after cryotherapy]/pretreatment eGFR). Based on the ΔeGFR results, we classified the patients into two groups: a preserved renal function group (ΔeGFR < 10%) and an impaired renal function group (ΔeGFR ≥ 10%). We then analyzed the relationships between the mRN score and ΔeGFR and between the mRN score and the chronic kidney disease (CKD) stage. RESULTS: The mean ΔeGFR for all patients was 5.5%. The mRN scores of the preserved renal function group (5.8 ± 0.3) were significantly lower than those of the impaired group (7.4 ± 0.3) (p < 0.001). When the mRN score cutoff value was set at 7 points, the mRN had 67.7% sensitivity, 72.7% specificity, 61.8% positive predictive value (PPV), 76.1% negative predictive value (NPV), and 70.7% accuracy for predicting impaired renal function. For predicting a deterioration of CKD stage, the mRN had 92.9% sensitivity, 67.2% specificity, 39.4% PPV, 97.6% NPV, and 72% accuracy. CONCLUSION: Our newly proposed modified RENAL nephrometry score was suggested to be useful for predicting renal function after renal cryotherapy.

Neoadjuvant Chemotherapy with Gemcitabine Plus Nab-Paclitaxel for Borderline Resectable Pancreatic Cancer Potentially Improves Survival and Facilitates Surgery.

BACKGROUND: Accumulation of evidence suggests that neoadjuvant chemotherapy improves the outcomes of borderline resectable pancreatic cancer (BRPC). Gemcitabine plus nab-paclitaxel (GnP) has been widely accepted as systemic chemotherapy for unresectable pancreatic cancer and reportedly results in remarkable tumor shrinkage. This study was performed to evaluate the safety and efficacy of neoadjuvant chemotherapy using neoadjuvant GnP for BRPC. METHODS: The medical records of 57 patients who underwent treatment of BRPC from 2010 to 2017 were retrospectively reviewed. The patient characteristics and short- and intermediate-term outcomes were compared between the GnP and upfront surgery (UFS) groups. RESULTS: The GnP group comprised 31 patients and the UFS group comprised 26 patients. The patient characteristics were comparable with the exception of a higher prevalence of arterial involvement in the GnP group. Twenty-seven of the 31 patients (87%) in the GnP group and all 26 patients in the UFS group underwent resection. The GnP group showed a significantly shorter operation time (429 vs. 509.5 min, p = 0.0068), less blood loss (760 vs. 1324 ml, p = 0.0115), and a higher R0 resection rate (100% vs. 77%, p = 0.0100) than the UFS group. Postoperative complications and hospital stay were comparable between the two groups, and no treatment-related mortality occurred in either group. Both the disease-free survival and overall survival times were significantly longer in the GnP group (p = 0.0018 and p = 0.0024, respectively). CONCLUSIONS: Neoadjuvant GnP is a safe and effective treatment strategy for BRPC. It potentially improves patients' prognosis and facilitates surgical procedures.

Prediction of Liver Fibrosis Using CT Under Respiratory Control: New Attempt Using Deformation Vectors Obtained by Non-rigid Registration Technique.

AIM: To investigate whether liver fibrosis can be predicted by quantifying the deformity of the liver obtained based on computed tomographic (CT) images scanned under respiratory control. MATERIALS AND METHODS: For dynamic CT of 47 patients, portal venous and equilibrium phases were scanned during inspiration and expiration, respectively. After rigid registration of the two images, non-rigid registration of the liver was performed, and the amount and direction of each voxel's shift during non-rigid registration was defined as the deformation vector. The correlation of each CT parameter for the obtained deformation vectors with the pathologically-proven degree of liver fibrosis was assessed using Spearman's rank correlation test. Receiver operating characteristic curve analysis was conducted for prediction of liver fibrosis. RESULTS: The standard deviation, coefficient of variance (CV) and skewness were significantly negatively correlated with the degree of liver fibrosis (p=0.030, 0.009 and 0.037, respectively). Of these measures, CV was best correlated and significantly decreased as liver fibrosis progressed (rho=-0.376). CV showed accuracies of 66.0-70.2%, and the areas under curves were 0.654-0.727 for prediction of fibrosis of grade F1 or greater, F2 or greater, F3 or greater and F4 fibrosis. CONCLUSION: The deformation vector is a potential CT parameter for evaluating liver fibrosis.

Impact of body mass index on CT attenuation of adrenal adenoma.

OBJECTIVE: To investigate whether lipid metabolism-related factors regulate unenhanced CT attenuation in adrenal adenoma (AA). MATERIALS AND METHODS: Thirty-six patients with surgically proven AAs were enrolled in this study. The patients' underlying diseases were the following: primary aldosteronism (n = 24), Cushing's syndrome (n = 8), subclinical Cushing's syndrome (n = 3) and non-functioning AA (n = 1). Unenhanced CT attenuation of AAs and liver was measured. Pathologically, clear cell ratio (CCR) constituting each AA was qualitatively assessed. Clinical data including tumor diameter, body mass index (BMI), hemoglobin A1c, triglyceride, total cholesterol, blood cortisol and plasma aldosterone levels were also obtained. Simple and multiple linear regression analyses were performed to evaluate the radiological and clinicopathological factors associated with CT attenuation of AAs for all patients and separately for 25 patients with primary aldosteronism or non-functioning AA. RESULTS: For all patients, there was a significant correlation between CT attenuation and each of CCR, BMI and blood cortisol levels (p < 0.05). For patients with primary aldosteronism or non-functioning AA, there was also a significant correlation between CT attenuation and CCR or BMI (p < 0.05). CONCLUSION: In addition to pathological factors, lipid-metabolism-related factors including BMI and blood cortisol levels can affect unenhanced CT attenuation of AA.

Image quality and diagnostic performance of free-breathing diffusion-weighted imaging for hepatocellular carcinoma.

AIM: To retrospectively evaluate the diagnostic performance of free-breathing diffusion-weighted imaging (FB-DWI) with modified imaging parameter settings for detecting hepatocellular carcinomas (HCCs). METHODS: Fifty-one patients at risk for HCC were scanned with both FB-DWI and respiratory-triggered DWI with the navigator echo respiratory-triggering technique (RT-DWI). Qualitatively, the sharpness of the liver contour, the image noise and the chemical shift artifacts on each DWI with b-values of 1000 s/mm2 were independently evaluated by three radiologists using 4-point scoring. We compared the image quality scores of each observer between the two DWI methods, using the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma and lesion-to-nonlesion contrast-to-noise ratios (CNRs) after measuring the signal intensity on each DWI with a b-factor of 1000 s/mm2. The average SNRs and CNRs between the two DWI methods were compared by the paired t-test. The detectability of HCC on each DWI was also analyzed by three radiologists. The detectability provided by the two DWI methods was compared using McNemar's test. RESULTS: For all observers, the averaged image quality scores of FB-DWI were: Sharpness of the liver contour [observer (Obs)-1, 3.08 ± 0.81; Obs-2, 2.98 ± 0.73; Obs-3, 3.54 ± 0.75], those of the distortion (Obs-1, 2.94 ± 0.50; Obs-2, 2.71 ± 0.70; Obs-3, 3.27 ± 0.53), and the chemical shift artifacts (Obs-1, 3.38 ± 0.60; Obs-2, 3.15 ± 1.07; Obs-3, 3.21 ± 0.85). The averaged image quality scores of RT-DWI were: Sharpness of the liver contour (Obs-1, 2.33 ± 0.65; Obs-2, 2.37 ± 0.74; Obs-3, 2.75 ± 0.81), distortion (Obs-1, 2.81 ± 0.56; Obs-2, 2.25 ± 0.74; Obs-3, 2.96 ± 0.71), and the chemical shift artifacts (Obs-1, 2.92 ± 0.59; Obs-2, 2.21 ± 0.85; Obs-3, 2.77 ± 1.08). All image quality scores of FB-DWI were significantly higher than those of RT-DWI (P < 0.05). The average SNR of the normal liver parenchyma by FB-DWI (11.0 ± 4.8) was not significantly different from that shown by RT-DWI (11.0 ± 5.0); nor were the lesion-to-nonlesion CNRs significantly different (FB-DWI, 21.4 ± 17.7; RT-DWI, 20.1 ± 15.1). For all three observers, the detectability of FB-DWI (Obs-1, 43.6%; Obs-2, 53.6%; and Obs-3, 45.0%) was significantly higher than that of RT-DWI (Obs-1, 29.1%; Obs-2, 43.6%; and Obs-3, 34.5%) (P < 0.05). CONCLUSION: FB-DWI showed better image quality and higher detectability of HCC compared to RT-DWI, without significantly reducing the SNRs of the liver parenchyma and lesion-to-nonlesion CNRs.

Mucinous nonneoplastic cyst of the pancreas: CT and MRI appearances.

PURPOSE: The purpose of this retrospective study was to evaluate imaging features of mucinous nonneoplastic cyst (MNNC) of the pancreas. MATERIALS AND METHODS: Three (0.9%) patients with MNNC of the pancreas were found in 335 surgically resected pancreatic cystic lesions. Three MDCT and two MRI/MRCP studies were retrospectively reviewed. RESULTS: Three cases of MNNC were found in the pancreatic neck, body, and tail, respectively. All the three cases were multilocular without communication with the main pancreatic duct (MPD), although upstream MPD dilatation was seen in two of the three cases. The signal intensity of the cyst fluid was low on T1-weighted, high on T2-weighted, and low on diffusion-weighted images. Cyst wall was thin in two cases, and the remaining case with obstructive pancreatitis showed visible cyst wall enhancement. CONCLUSION: Imaging findings of MNNC of the pancreas were nonspecific without communication with the MPD. Cyst wall is typically thin without visible enhancement.

Validity of the management strategy for intraductal papillary mucinous neoplasm advocated by the international consensus guidelines 2012: a retrospective review.

PURPOSE: The aim of this study was to investigate the validity of the management strategy for intraductal papillary mucinous neoplasms (IPMNs) advocated by the international consensus guidelines 2012 (ICG2012). METHODS: The medical records of 49 patients who underwent pancreatectomy for IPMN were retrospectively reviewed. RESULTS: According to preoperative imaging, 10 patients (20 %) had main-duct IPMNs, 20 (41 %) had mixed IPMNs, and 19 (39 %) had branch-duct IPMNs, with malignancy frequencies of 80, 15, and 37 %, respectively. Twenty-seven patients had high-risk stigmata and 21 had worrisome features, with malignancy frequencies of 59 and 10 %, respectively. The sensitivity, specificity, and positive and negative predictive values of high-risk stigmata for malignancy were 88, 65, 59, and 91 %, respectively. Lesions were malignant in 88 % of patients with an enhanced solid component, which was significantly correlated with the prevalence of malignancy (P < 0.01). However, of the 10 patients who underwent pancreatectomy solely due to a main pancreatic dilation of ≥10 mm, 9 (90 %) had benign IPMNs. CONCLUSIONS: Many mixed IPMNs defined according to ICG2012 are benign. Although the management strategy advocated by ICG2012 has been improved relative to the Sendai criteria, the different high-risk stigmata carry unequal weights. Consequently, ICG2012 remains suboptimal for predicting malignant IPMN.

Apparent diffusion coefficient: An associative factor for recurrence after nephrectomy in localized renal cell carcinoma.

PURPOSE: To investigate whether the apparent diffusion coefficient (ADC) of a tumor is associated with recurrence after nephrectomy in renal cell carcinoma (RCC) MATERIALS AND METHODS: We retrospectively studied 49 patients with localized RCC who underwent 1.5T magnetic resonance imaging (MRI) including diffusion-weighted imaging preoperatively. Fifteen patients had recurrent disease after surgery. The ADC was measured by placing a region-of-interest in a solid region of each tumor on the ADC map. We named the average value of the three ADC values the "average ADC" and the lowest ADC value among the three as the "minimum ADC." The correlations between clinicopathological factors including patient age and gender, tumor side, tumor size, growth/invasion pattern, Fuhrman grade, histological subtype, venous invasion, average and minimum ADCs, and disease-free survival were analyzed by Cox proportional hazards model. RESULTS: In univariate analysis, tumor size, venous invasion, mean ADC, and minimum ADC showed significant correlations with disease-free survival (P < 0.05). In multivariate analysis, only venous invasion and minimum ADC were significant (P < 0.05). The 5-year disease-free survival rate of the low minimum ADC group was 51.6%, while that of the high minimum ADC group was 85.1%. CONCLUSION: The minimum ADC of a tumor, although not as pronounced as venous invasion, was found to be an independent associative factor for recurrence after nephrectomy in patients with localized RCC.

Current radiologist workload and the shortages in Japan: how many full-time radiologists are required?

PURPOSE: To clarify the workload of certified radiologists and to estimate the current manpower shortages in Japan. METHODS: We conducted a questionnaire survey for accredited training institutions. The contents included the radiologist employment pattern (full vs. part time), the number of computed tomography (CT) and magnetic resonance imaging (MRI) examinations and their radiology reports, the number of radiation therapy planning sessions, and the time per week spent for each work activity. We also used the hospital survey reports of Japan's Ministry of Health, Labor, and Welfare in our analyses. RESULTS: The estimated numbers of CT and MRI interpretation reports and radiation treatment plans that one full-time radiologist could complete within 1 hospital day (8 h) were 19.9 and 1.22, respectively. To complete all CT and MRI reports, at least 2.09 times more full-time diagnostic radiologists are needed in Japan. For radiation therapy, at least 1.23 times more full-time radiation oncologists are necessary at large- and medium-scale hospitals, although the number of radiation oncologists needed in Japan is balanced to the current number. CONCLUSION: The number of full-time certified diagnostic radiologists for CT and MRI interpretation in Japan is insufficient. Centralized radiation therapy facilities may be more efficient for meeting the increasing demand.

Optimization and Clinical Feasibility of Free-breathing Diffusion-weighted Imaging of the Liver: Comparison with Respiratory-Triggered Diffusion-weighted Imaging.

PURPOSE: We compared the image quality of free-breathing diffusion-weighted imaging (FB-DWI) to that of respiratory-triggered DWI (RT-DWI) after proper optimization. MATERIALS AND METHODS: Three healthy subjects were scanned to optimize magnetic resonance (MR) parameters of FB-DWI to improve image quality, including spatial resolution, image noise, and chemical shift artifacts. After this optimization, we scanned 32 patients with liver disease to assess the clinical feasibility of the optimized FB-DWI. Of the 32 patients, 14 had a total of 28 hepatocellular carcinomas (HCCs), four had a total of 15 metastatic liver tumors, and the other 14 had no tumor. Qualitatively, we compared the image quality scores of FB-DWI with those of RT-DWI with the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma, lesion-to-nonlesion contrast-to-noise ratios (CNRs) and apparent diffusion coefficient (ADC) values of the liver parenchyma and liver tumor by the paired t-test. RESULTS: The average scores of image quality for sharpness of liver contour, image noise, and chemical shift artifacts were significantly higher for FB-DWI than RT-DWI (P < 0.05). SNRs, CNRs, and ADC values of the liver parenchyma and tumors did not differ significantly between the 2 DWI methods. CONCLUSION: Compared with RT-DWI, the optimized FB-DWI provided better spatial resolution, fewer artifacts, and comparable SNRs, lesion-to-nonlesion CNRs, and ADC values.

Pathological manifestation of difference in washout pattern of adrenal hyperplasia on dynamic CT.

INTRODUCTION: The relationship between the washout pattern and constituent cell in adrenal hyperplasia (AH) has not been fully investigated. The purpose of this study was to elucidate the radiological or pathological factors determining the washout pattern of AH on dynamic CT. METHODS: Ten patients with 14 surgically proven AHs were enrolled. Dynamic CT was scanned before (pre-contrast image) and 60 seconds (early phase) and 240 seconds (delayed phase) after administration of iodine contrast. The absolute percentage washout (APW) of each nodular lesion was calculated using the following formula: APW(%) = (TAearly-TAdelay)/(TAearly-TApre) × 100, when TApre, TAearly and TAdelay were defined as tumour attenuation values of pre-contrast, early and delayed phases, respectively. Pathologically, the clear cell ratio (CCR) constituting each nodular lesion was qualitatively assessed. Regression analysis was performed to evaluate a correlation between each pair of CCR, TApre, (TAearly-TAdelay) and APW. RESULTS: There was a significant correlation between each pair of CCR, TApre and APW. CCR decreased as TApre increased (r = 0.81, P < 0.001). APW increased as CCR decreased (r = 0.80, P < 0.001) or as TApre increased (r = 0.74, P < 0.01). CONCLUSIONS: The key factors of washout pattern of AH on dynamic CT were CCR and TApre. The difference in constituent cell was associated with variability in APW of AH.

Role of tumor-associated macrophages in the angiogenesis of well-differentiated hepatocellular carcinoma: pathological-radiological correlation.

The role of tumor-associated macrophages (TAMs) in hepatocellular carcinoma (HCC) has not been fully investigated. The aim of the present study was to clarify whether TAMs are associated with the angiogenesis of HCC during its multistep development, especially at an early stage. Forty­three well-differentiated HCCs and 30 well- to moderately differentiated HCCs (nodule-in-nodule lesion) were used. We immunohistochemically assessed microvessel density (by CD34) and macrophage count (by CD68 or CD163). Computed tomography hepatic angiography (CTHA) was performed for 26 well-differentiated HCCs and all 30 well- to moderately differentiated HCCs. The pathological analysis of the 43 well-differentiated HCCs revealed a positive correlation between microvessel density and macrophage count (p=0.0026, r=0.4486). Based on the CTHA findings, 26 well-differentiated HCCs classified into a hyperattenuation group (n=14) and a hypo- or isoattenuation group (n=12). The microvessel density and macrophage count of the hyperattenuation group were significantly higher than those of the hypo- or isoattenuation group (p=0.0372 and p=0.0476). In the 30 well- to moderately differentiated HCCs, microvessel density of the moderately differentiated components was significantly higher than that of the well-differentiated components (p<0.0001). However, the macrophage count of the moderately differentiated component was significantly lower than that of the well-differentiated component (p<0.0001). All the moderately differentiated components showed marked hyperattenuation on CTHA. Tumor vascularity was correlated with macrophage count in the tumor when limited to well-differentiated HCCs. TAMs may have a role in promoting angiogenesis of HCC at an early stage during its multistep development.

Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MR finding of radiation-induced hepatic injury: relationship to absorbed dose and time course after irradiation.

PURPOSE: To evaluate if Gd-EOB-DTPA-enhanced MRI could identify liver tissue damage caused by radiation exposure in patients undergoing external beam radiation therapy. MATERIALS AND METHODS: We enrolled 11 patients who underwent Gd-EOB-DTPA-enhanced MRI during or after radiotherapy in which the radiation field included the liver. External beam radiotherapy was delivered through multiple fields using a 10-MV linear accelerator. The hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI were qualitatively evaluated for the presence of a decreased uptake of Gd-EOB-DTPA in the irradiated area in the liver. Next, signal intensity (SI) ratio of the irradiated area to the non-irradiated liver parenchyma was also calculated. The absorbed dose of the irradiated area in the liver was standardized using equivalent dose in 2Gy fraction (EQD2) and biological effective dose (BED). The results of qualitative analysis were compared with EQD2 or BED, and linear regression analysis was performed between EQD2 or BED and SI ratio. RESULTS: Twenty-two irradiated areas were evaluated. Qualitative analysis revealed a decreased uptake of Gd-EOB-DTPA in 14 areas and no decreased uptake of Gd-EOB-DTPA in eight areas. The thresholds of EQD2 and BED causing a decreased uptake of Gd-EOB-DTPA were considered to be 24 to 29Gy and 29 to 35Gy, respectively. Quantitatively, SI ratio decreased as EQD2 or BED increased (r=0.89, p<0.001), and the inverse relationship between signal enhancement and the absorbed dose in the irradiated area was obtained. One area with EQD2 of 50Gy and BED of 60Gy showed a slightly decreased uptake of Gd-EOB-DTPA on the 40th day but a clearly decreased uptake of Gd-EOB-DTPA on the 123rd day from initiation of radiotherapy. CONCLUSIONS: Gd-EOB-DTPA-enhanced MRI described RLI as a decreased uptake of Gd-EOB-DTPA matching the irradiated area. The occurrence of this finding was significantly correlated with the absorbed dose of the irradiated area in the liver.