Evaluation of Incidental Findings on Abdominopelvic CT: Potential Benefit of Photon-counting Detector CT Over Conventional Single-energy CT.

PURPOSE: To assese of potential benefint of photon-counting detector CT (PCD-CT) over conventional single-energy CT (CSE-CT) on accurate diagnosis of incidental findings with high clinical significance (IFHCS). MATERIALS AND METHODS: This retrospective study included 365 patients who initially underwent abdominopelvic contrast-enhanced CT (AP-CECT) without non-enhancement (PCD-CT: 187 and CSE-CT: 178). We selected IFHCS and evaluated their diagnosability using CE-CT alone. IFHCSs that could not be diagnosed with only CE-CT were evaluated using additional PCD-CT postprocessing techniques, including virtual non-contrast image, low keV image, and iodine map. A PCD-CT scanner (NAEOTOM Alpha, Siemens Healthineer, Erlangen, Germany) was used. RESULTS: Thirty-nine IFHCSs (PCD-CT: 22 and CSE-CT: 17) were determined in this study. Seven IFHCSs in each group were able to diagnose with only CE-CT. Fifteen IFHCSs were able to diagnose using the additional PCD-CT postprocessing technique, which was useful for detecting and accurately diagnosing 68.2% (15/22) of lesions and 65% (13/20) of patients. All IFHCSs were accurately diagonosed with PCD-CT. CONCLUSION: PCD-CT was useful for characterizing IFHCSs that are indeterminate at CSE-CT. PCD-CT offered potential benefit of PCD-CT over conventional single-energy CT on evaluation of IFHCS on only abdominopelvic CT.

Computed diffusion-weighted imaging with a low-apparent diffusion coefficient-pixel cut-off technique for breast cancer detection.

OBJECTIVE: This study aimed to compare the image quality and diagnostic performance of computed diffusion-weighted imaging (DWI) with low-apparent diffusion coefficient (ADC)-pixel cut-off technique (cDWI cut-off) and actual measured DWI (mDWI). METHODS: Eighty-seven consecutive patients with malignant breast lesions and 72 with negative breast lesions who underwent breast MRI were retrospectively evaluated. Computed DWI with high b-values of 800, 1200, and 1500 s/mm2 and ADC cut-off thresholds of none, 0, 0.3, and 0.6 (×10-3 mm2/s) were generated from DWI with two b-values (0 and 800 s/mm2). To identify the optimal conditions, two radiologists evaluated the fat suppression and lesion reduction failure using a cut-off technique. The contrast between breast cancer and glandular tissue was evaluated using region of interest analysis. Three other board-certified radiologists independently assessed the optimised cDWI cut-off and mDWI data sets. Diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. RESULTS: When an ADC cut-off threshold of 0.3 or 0.6 (× 10-3 mm2/s) was applied, fat suppression improved significantly (p < .05). The contrast of the cDWI cut-off with a b-value of 1200 or 1500 s/mm2 was better than the mDWI (p < .01). The ROC area under the curve for breast cancer detection was 0.837 for the mDWI and 0.909 for the cDWI cut-off (p < .01). CONCLUSION: The cDWI cut-off provided better diagnostic performance than mDWI for breast cancer detection. ADVANCES IN KNOWLEDGE: Using the low-ADC-pixel cut-off technique, computed DWI can improve diagnostic performance by increasing contrast and eliminating un-suppressed fat signals.

A case of incomplete duplication of the portal vein associated with multiple congenital anomalies.

Double portal veins are a duplication of the portal vein and normal portal vein with an accessory portal vein. We report a case of a 63-year-old asymptomatic female with double portal veins. There was fat accumulation observed in the area which was supplied by the first portal vein in normal position, and fatty sparing of the liver was observed in the area which was supplied by the second portal vein in the preduodenal position. The 2 portal veins were equal in size. Furthermore, the patient presented with multiple congenital anomalies, including double inferior vena cava, splenic lobulation, and accessory liver lobe. Therefore, double portal veins in our case were thought to be an incomplete duplication of the portal vein with multiple congenital anomalies.

Combined primary hepatic neuroendocrine carcinoma and hepatocellular carcinoma: case report and literature review.

BACKGROUND: Hepatocellular carcinoma (HCC) can grow in a mosaic pattern, often combined with various non-hepatocellular cells. However, HCC combined with a neuroendocrine carcinoma (NEC) component is rarely reported, and its clinical features, origin, diagnosis, and behavior have not been established. In the literature, mixed HCC-NEC tumors are categorized as either collision type or combined type, depending on their microscopic features. Here, we report a patient with a combined-type HCC-NEC tumor. CASE PRESENTATION: An asymptomatic 84-year-old woman was found to have a solid mass in the right lobe of the liver. Laboratory and radiologic examinations showed typical findings of HCC, including arterial-phase enhancement, and portal- and delay-phase washout. She was treated by partial laparoscopic hepatectomy of segment 5. Pathological examination showed that the tumor was predominantly HCC, partly admixed with an NEC component. A transitional zone between the HCC and NEC tissues was also observed. The tumor was finally diagnosed as a combined-type primary mixed NEC-HCC tumor. After the preoperative diagnosis, the patient underwent somatostatin receptor scintigraphy to detect the primary NEC lesion, but no accumulation was found in any other part of her body. She has been free of recurrence for 9 months since the surgery. CONCLUSION: Mixed HCC-NEC tumors are extremely rare, and correct diagnosis requires multidisciplinary collaboration. The accumulation of further cases is needed to help understand the exact pathology, diagnosis, and treatment of this disease.

Outcomes of Local Excision plus Chemoradiotherapy in Patients with T1 Rectal Cancer.

OBJECTIVE: The National Comprehensive Cancer Network (NCCN) guidelines recommend local excision and observation as standard treatment for selected patients with clinical T1N0M0 rectal cancer. In patients with pathological T1 (pT1) rectal cancer who received local excision, the local recurrence rate is at least 10%. We studied oncological outcomes in patients with pT1 rectal cancer who received chemoradiotherapy (CRT) after local excision. METHODS: Local excision was performed in 65 patients with clinical T1N0M0 rectal cancer (≤8 cm from the anal verge, tumor size < 30 mm, well or moderately differentiated adenocarcinoma). The patients received CRT (40 or 45 Gy in 1.8-2.0 fractions with concurrent oral UFT [tegafur/uracil] or S-1 [tegafur/gimeracil/ote-racil]) after confirmation of pT1 and negative margins. RESULTS: Patients who had pT2 cancer or who did not provide informed consent were excluded. The remaining 50 patients additionally received CRT. The CRT was completed in 48 patients (96%). The median follow-up period was 71 months. Local recurrence occurred in 1 patient (2%). Distant metastases occurred in 3 patients (6%). The 5-year disease-free survival rate was 86%, and the 5-year overall survival rate was 92%. CONCLUSIONS: Our study suggested that multidisciplinary treatment with local excision plus CRT can be used as a treatment option in selected patients with clinical T1N0M0 rectal cancer.

Mucinous components assessed by magnetic resonance imaging in primary rectal cancer tissue before and after chemoradiotherapy and tumor response.

BACKGROUND: Mucinous rectal carcinoma has been reported to have a lower survival rate and a poorer histologic response to chemoradiotherapy(CRT). Magnetic resonance imaging (MRI) can accurately evaluate the amount of mucin pools (MP) in primary cancer tissue. We compared the degree of MP on MRI before and after CRT with the histologic findings of resected specimens to investigate the predictors of response to CRT. METHODS: The study group comprised 205 patients with rectal adenocarcinoma who received preoperative CRT. MPs were measured on MRI before and after CRT and in resected specimens. The degree of MP was classified into five classes according to the MP area ratio: 0%, class I; 1 to 19%, class II; 20 to 49%, class III; and 50% or higher, class IV. RESULTS: The degree of MP on MRI was largely unchanged after CRT; however, the MP on MRI after CRT was underestimated in 26.3% of patients as compared with that in resected specimens. A pathological complete response was obtained in patients who initially had no MP or had an MP ratio of less than 20%. The tumor volume was significantly greater, and the rates of tumor shrinkage and T downstaging were significantly lower in patients who had an MP area ratio of 20% or higher before CRT than in those who had an MP area ratio of less than 20%. CONCLUSIONS: The MP area ratio measured on MRI before treatment was closely associated with the response to CRT and is a potentially useful predictor of treatment response.

Right Aortic Arch with Mirror-image Branching in Adults: Evaluation Using CT.

OBJECTIVE: We evaluated radiological findings and clinical significance of right aortic arch with mirror-image branching (RAMI) in adults using data from computed tomography (CT) examinations. MATERIAL AND METHODS: We reviewed recorded reports and CT images obtained from university and branch hospitals for RAMI in adults. The RAMI incidence in adults found on CT was assessed. Associated congenital and acquired cardiovascular diseases were evaluated. RESULTS: A total of 27 cases (14 men, 13 women; mean age, 59.4 ± 18.3 years) of RAMI were found. Among 107,014 cases in three hospitals, the RAMI incidence in the first, second, and third Tokai University hospitals were 0.018%, 0.012%, and 0.012%, respectively. Eight cases had high aortic arches and four cases had aortic diverticulum (AD) in proximal descending aorta. Three cases had a history of tetralogy of Fallot. One case with an absent left pulmonary artery and three cases with an aberrant left brachiocephalic vein were found incidentally. Two cases were associated with AD aneurysm and vascular ring formation. One case had stenosis of the left subclavian artery due to injury. CONCLUSION: Cases of RAMI found in CT examinations in adults were extremely rare. Some cases were associated with congenital anomalies and/or acquired cardiovascular disease.

MR Imaging with Apparent Diffusion Coefficient Histogram Analysis: Evaluation of Locally Advanced Rectal Cancer after Chemotherapy and Radiation Therapy.

Purpose To determine response to neoadjuvant chemotherapy and radiation therapy in patients with locally advanced rectal cancer (LARC) by using magnetic resonance (MR) apparent diffusion coefficient (ADC) histogram analysis. Materials and Methods Ninety-two patients with LARC underwent MR imaging with rectal barium before and after chemotherapy and radiation therapy (CRT). Rectal expansion with barium expanded the lumen, provided similar imaging geometry before and after CRT, and eliminated fecal matter, air, and residual fluid. T2-weighted images, the percentage change in ADC, and ADC histogram skewness and kurtosis were assessed. The histopathologic tumor regression grade (TRG) ranged from 1a (66%-99% residual tumor cells) to 3 (no residual cells). The Wilcoxon signed-rank test, the Spearman correlation test, multivariable linear regression, and one-way analysis of variance were used to determine post- and pretreatment differences and correlations between tumor size and ADC. Results Of the 92 patients, 16 (17.4%) had TRG 3, 27 (29.3%) had TRG 2b, 24 (26.1%) had TRG 2a, 14 (15.2%) had TRG 1b, and 11 (12%) had TRG 1a. Post-CRT skewness (regression coefficient = 10.9, P = .06) and percentage ADC change (regression coefficient = -0.18, P = .03) were associated with the percentage of residual tumor. Post-CRT skewness and percentage ADC change, respectively, showed negative and positive correlation with histopathologic TRG (post-CRT skewness: P = .024; percentage ADC change: P = .001). Conclusion In patients with LARC, post-CRT skewness of the ADC histogram and percentage change in ADC were useful for predicting a favorable response to neoadjuvant CRT. © RSNA, 2018 Online supplemental material is available for this article.

Aberrant Left Brachiocephalic Vein versus Persistent Left Superior Vena Cava without Bridging Vein in Adults: Evaluation on Computed Tomography.

Objective: Persistent left superior vena cava without bringing vein (PLSVC w/o BV) is a common thoracic venous anomaly, while aberrant left brachiocephalic vein (ALBCV) is an uncommon condition. We compared the incidences of the two venous anomalies and assessed congenital cardiovascular diseases (CCDs) in adults using computed tomography (CT). Materials and Methods: We reviewed the recorded reports or CT images of 49,494 adults for PLSVC w/o BV and ALBCV in two hospitals. We determined incidences of two venous anomalies and the rate of associated CCDs. Results: 76 PLSVCs w/o BV and 27 ALBCVs were found. The incidence of PLSVC w/o BV was 0.15% and the incidence of ALBCV was 0.055%. PLSVC w/o BV had higher incidence than ALBCV (p<0.001). Four PLSVCs w/o BV and one ALBCV were associated with congenital heart diseases. Two PLSVCs w/o BV and four ALBCVs were associated with congenital aortic arch anomaly (CAAA). ALBCV had higher incidence of associated CAAA than PLSVC w/o BV (P=0.02). Conclusion: The incidence of ALBCV was <50% that of PLSVC w/o BV. The two venous anomalies found on CT during adulthood were rarely associated with CCDs.

Congenital anomalies of the left brachiocephalic vein detected in adults on computed tomography.

PURPOSE: Anomalous left brachiocephalic vein (BCV) is a rare and less known systemic venous anomaly. We evaluated congenital anomalies of the left BCV in adults detected during computed tomography (CT) examinations. MATERIALS AND METHODS: This retrospective study included 81,425 patients without congenital heart disease who underwent chest CT. We reviewed the recorded reports and CT images for congenital anomalies of the left BCV including aberrant and supernumerary BCVs. The associated congenital aortic anomalies were assessed. RESULTS: Among 73,407 cases at a university hospital, 22 (16 males, 6 females; mean age, 59 years) with aberrant left BCVs were found using keyword research on recorded reports (0.03%). Among 8018 cases at the branch hospital, 5 (4 males, 1 female; mean age, 67 years) with aberrant left BCVs were found using CT image review (0.062%). There were no significant differences in incidences of aberrant left BCV between the two groups. Two cases had double left BCVs. Eleven cases showed high aortic arches. Two cases had the right aortic arch, one case had an incomplete double aortic arch, and one case was associated with coarctation. CONCLUSION: Aberrant left BCV on CT examination in adults was extremely rare. Some cases were associated with aortic arch anomalies.

A Modified Classification of Prognostic Factors Based on Pathological Stage and Tumor Regression Grade in Patients with Rectal Cancer Who Receive Preoperative Chemoradiotherapy.

OBJECTIVE: The histologic response to neoadjuvant chemoradiotherapy (CRT) has been intimately related to outcomes in locally advanced rectal cancer. However, reliable prognostic factors have yet to be established. SUBJECTS AND METHODS: The study group comprised 198 patients with locally advanced rectal cancer who received CRT. A modified classification based on the combination of ypStage and tumor regression grade (TRG) was developed. ypStage II with TRG 2 was classified as ypTRGstage IIA, and ypStage II with TRG 3 or 4 was classified as ypTRGstage IIB. ypStage 0 and ypStage I were classified as ypTRGstage I, and ypStage III was classified as ypTRGstage III. RESULTS: The 5-year disease-free survival (DFS) was 83% in ypTRGstage I, 86% in ypTRGstage IIA, 57% in ypTRGstage IIB, and 60% in ypTRGstage III (p = 0.0001). The 5-year DFS in ypTRGstage IIA did not differ significantly from that in ypStage 0 (p = 0.865) or ypStage I (p = 0.585). The 5-year DFS in ypStage IIB did not differ from that in ypStage III (p = 0.912). Multivariate analysis showed that ypTRGstage was an independent risk factor for DFS. CONCLUSION: A modified classification allows patients with ypStage II locally advanced rectal cancer to be clearly divided into two groups: responders and nonresponders.

The Apparent Diffusion Coefficient (ADC) as a Potential Marker of Inflammation Associated with Body Abscesses.

OBJECTIVE: To assess the feasibility of apparent diffusion coefficient analysis in evaluating the inflammatory severity of extracranial abscesses. METHODS: This retrospective study included 23 patients with solitary body abscesses (except those in the brain) who underwent 1.5-T diffusion-weighted magnetic resonance imaging (DWI) at b-values of 0 and 1000 s/mm2. Three types of the Apparent Diffusion Coefficient (ADC) measurements of abscesses were performed: the mean ADC value in region of interest (ROI), volume of interest (VOI), and histogram analysis of the ADC distribution in the VOI. Furthermore, two different areas were used: high-intensity area on b = 0 and b = 1000 s/mm2 images. Subsequently, correlations between ADC data and C-reactive protein (CRP) levels were assessed using Pearson's correlation coefficient (R) analyses. RESULTS: The strongest correlation was observed between the mean ADC value in VOI and CRP level (R = 0.78, P < 0.01), followed by ROI (R = 0.77, P < 0.01) by using the high-intensity area on the b = 0 s/mm2 images. CONCLUSION: The mean ADC value in the ROI encompassing the abscess at a b-value of 0 s/mm2 may be useful to assess the inflammatory activity of an abscess in daily practice.

Bone morphogenetic protein-2 expression in an intraductal papillary mucinous neoplasm with marked ossification: A case report.

Intratumoral ossification has been reported in a number of epithelial tumors, but its presence in intraductal papillary mucinous neoplasms (IPMNs) is very rare. Herein, we present a rare case of IPMN with marked ossification. A 56-year-old Japanese man was under follow-up for a previously diagnosed IPMN. Seven years later, he was found to have dilatation of the main pancreatic duct and an enlarged solid mass, for which pancreaticoduodenectomy was performed. Macroscopically, multiple and cystically dilated pancreatic branch ducts, as well as a dilated main pancreatic duct, were identified. There was a solid, polypoid hard mass measuring 15 × 12 mm in the cystically dilated branch of the duct in the pancreatic head. Histological examination revealed papillary proliferation of atypical cuboidal or columnar epithelial cells in the dilated main and branch pancreatic ducts. The solid mass included an invasive adenocarcinoma component with a tubular or trabecular structure that showed pronounced ossification. We diagnosed the patient with invasive IPMN accompanied by marked ossification. Immunohistochemically, tumor cells in both the non-invasive and invasive lesions expressed bone morphogenetic protein-2 (BMP-2). While the mechanism of intratumoral ossification is unclear, it may have involved BMP-2 in the present case.

Duodenal Emphysema Complicated with Superior Mesenteric Artery Syndrome in a Patient with Cerebral Paralysis: A Case Report.

Superior mesenteric artery syndrome (SMAS) is characterized by an arteriomesenteric duodenal compression commonly resulting from significant weight loss. Vomiting is the most frequent symptom. SMAS can be complicated by massive gastric dilatation. Patients with cerebral palsy have various factors that can predispose them to SMAS. In this paper, we report a rare case of SMAS complicated by duodenal, peritoneal and retroperitoneal emphysema in a patient with cerebral paralysis, referring to the relevant literature. In this case, severe vomiting associated with epilepsy and weight loss may have contributed to the development of duodenal emphysema.

Assessment of renal shape of horseshoe kidney with multidetector row CT in adult patients: relationship between urolithiasis and renal isthmus.

OBJECTIVE: The aim of this study was to evaluate the relationship between urolithiasis and characteristics of renal shape in adult patients with horseshoe kidney (HSK) diagnosed on multidetector row computed tomography (MDCT). METHODS: We evaluated 36 patients with HSK and urolithiasis (Group A) and 70 patients with HSK without urolithiasis (Group B) whose disease was diagnosed on non-contrast MDCT. Two radiologists measured minimum width of the renal isthmus and maximum length of the renal pelvis and evaluated coexisting neoplastic diseases on axial computed tomographic (CT) images with 5-mm reconstruction, and we compared those measurements between the Groups A and B. RESULTS: The overall mean maximum length of the renal pelvis, 12.7±9.2 mm, did not differ significantly between the 2 groups. Minimum isthmus width was larger in patients with HSK and urolithiasis (11.0±5.6 mm), than those without urolithiasis (9.5±5.1 mm). No patient in either groups had a urological renal tumor. CONCLUSIONS: Patients of HSK might have tendency of a high incidence of stone formation. Because urolithiasis is a risk factor for tumors of the renal pelvis, monitoring of patients with HSK requires careful attention to isthmus width on CT images.

Partial splenic embolisation using n-butyl cyanoacrylate: intraprocedural evaluation by magnetic resonance imaging.

OBJECTIVES: To evaluate the use of diffusion-weighted imaging (DWI) for estimating infarcted splenic volume during partial splenic embolisation (PSE) using n-butyl cyanoacrylate (NBCA). METHODS: Twenty consecutive patients (57.2 ± 11.7 years) with hypersplenism underwent PSE. Intrasplenic branches were embolised using NBCA via a 2.1-French microcatheter aiming at infarction of 50 to 80 % of total splenic volume. Immediately after PSE, signal intensities (SI) of embolised and non-embolised splenic parenchyma were measured on DWI. Semi-automated volumetry (SAV) on DWI was compared with conventional manual volumetry (MV) on contrast-enhanced CT 1 week after PSE. Platelet counts were recorded before and after PSE. RESULTS: The SI on DWI in the embolised parenchyma decreased significantly (P < 0.01) to 24.7 ± 8.1 % as compared to non-embolised parenchyma. SAV and MV showed a strong correlation (r = 0.913 before PSE, r = 0.935 after PSE, P < 0.01) and significant (P < 0.01) reduction of normal splenic volume was demonstrated on both SAV (71.9 ± 12.4 %) and MV (73.6 ± 9.3 %) after PSE. Based on the initial SAV, three patients (15 %) underwent additional branch embolisation to reach sufficient infarction volume. Platelet counts elevated significantly (522.8 ± 209.1 %, P < 0.01) by 2 weeks after PSE. No serious complication was observed. CONCLUSION: Immediate SI changes on DWI after PSE allowed semi-automated splenic volumetry on site. KEY POINTS: • Partial splenic embolisation (PSE) is an important interventional technique for hypersplenism • Diffusion-weighted MR reveals an immediate decrease in signal in the embolised parenchyma • Such signal reduction permits semi-automated splenic volumetry on site. • This allows precise quantification of the amount of parenchyma infarcted, avoiding additional PSE.

Small serotonin-positive pancreatic endocrine tumors caused obstruction of the main pancreatic duct.

We report 2 cases of pancreatic endocrine tumors that caused obstruction of the main pancreatic duct (MPD). A 49-year-old asymptomatic man was referred to our institution because dilation of the MPD was revealed by abdominal ultrasonography (US). No tumor was detected by endoscopic ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The diameter of the MPD was > 20 mm at the body, and no dilation was noted at the head. Although malignancy was not confirmed through cytology or imaging, pancreatic cancer was strongly suspected. Pancreaticoduo- denectomy was performed. Pathological and immunohistochemical examination revealed a 5 mm × 3 mm serotonin-positive endocrine tumor. Fibrosis was present around the MPD and seemed to cause stricture. A 32-year-old asymptomatic man had elevated serum amylase, and US demonstrated dilation of the MPD. No tumor was detected by CT and MRI. Pancreatic cancer was suspected due to stricture and dilation of the MPD. Pancreatectomy of middle part of pancreas was performed. Pathological and immunohistochemical examination revealed a serotonin-positive endocrine tumor sized 5 mm × 4 mm. We report 2 cases of serotonin-positive pancreatic endocrine tumors that caused stricture of the MPD in spite of the small size of the tumor.

Diffusion magnetic resonance imaging with gadofosveset trisodium as a negative contrast agent for lymph node metastases assessment.

PURPOSE: The aim of this study was to assess the feasibility of using intravenously administered gadofosveset trisodium as a negative contrast agent for lymph node (LN) assessment with diffusion-weighted imaging (DWI) using a VX2 tumor model in rabbits. MATERIALS AND METHODS: VX2 cells were injected in the right hind limb of five Japanese white rabbits to induce ipsilateral popliteal LN metastasis. DWI was performed before and every 7.5 min (until 1 h) after intravenous gadofosveset trisodium administration, at 1.5 T. Signal intensities (SIs) of right (metastatic) and left (nonmetastatic) popliteal LNs at each time point were measured and compared to each other using two-sided unpaired t-tests. RESULTS: The SIs of metastatic lymph nodes were significantly higher (P < 0.05) than those of nonmetastatic LNs at each time point after intravenous gadofosveset trisodium administration. Although the SI of metastatic LNs was significantly higher (P = 0.0237) than that of nonmetastatic LNs before contrast injection, this difference became even more significant (P ≤ 0.0105) after gadofosveset trisodium administration. CONCLUSION: The SI of metastatic LNs at DWI is less suppressed than that of nonmetastatic LNs after the intravenous administration of gadofosveset trisodium. Therefore, intravenously administered gadofosveset trisodium shows promise for use as a negative contrast agent for discriminating metastatic from nonmetastatic LNs at DWI.