Masanori Nakajo

Histogram Analysis of Apparent Diffusion Coefficient in Differentiating Pancreatic Adenocarcinoma and Neuroendocrine Tumor.

AbstractThe aim of this study was to investigate whether histogram analysis in diffusion-weighted (DW) magnetic resonance imaging (MRI) can help differentiate pancreatic adenocarcinomas from neuroendocrine tumors.Sixty-four patients with histologically confirmed 53 pancreatic adenocarcinomas or 19 neuroendocrine tumors underwent DW MRI. We evaluated the pixel distribution histogram parameters (mean, skewness, kurtosis, and entropy) of the apparent diffusion coefficient (ADC) values derived from b-values of 0 and 200 (ADC200), 0 and 400 (ADC400), or 0 and 800 (ADC800) s/mm2. Histogram parameters were compared between pancreatic adenocarcinomas and neuroendocrine tumors, and the diagnostic performance was evaluated by using receiver operating characteristic (ROC) analysis.The mean ADC200 and ADC400 were significantly higher in neuroendocrine tumors than in pancreatic adenocarcinomas (P = 0.001 and P = 0.019, respectively). Pancreatic adenocarcinomas showed significantly higher skewness and kurtosis on ADC400 (P = 0.007 and P = 0.001, respectively) and ADC800 (P = 0.001 and P = 0.001, respectively). With all b-value combinations, the entropy of ADC values was significantly higher in pancreatic adenocarcinomas (P < 0.001 for ADC200; P = 0.001 for ADC400; P < 0.001 for ADC800), and showed the highest area under the ROC curve for diagnosing adenocarcinomas (0.77 for ADC200, 0.76 for ADC400, and 0.78 for ADC800).ADC histogram analysis of DW MRI can help differentiate pancreatic adenocarcinomas from neuroendocrine tumors.

Computed tomographic features of two cases of acute gastric anisakiasis

Little is known about the detailed computed tomography (CT) features of acute gastric anisakiasis. Our two cases showed transiently swollen gastric folds comprised of the remarkably thickened contrast little-enhanced submucosal layer with little-thickened contrast-enhanced mucosal and muscular-serosal layers on multi-detector row CT. When CT demonstrates the swollen gastric folds in acute abdomen, acute gastric anisakiasis should be included in the differential diagnosis.

ADC histogram analysis for adrenal tumor histogram analysis of apparent diffusion coefficient in differentiating adrenal adenoma from pheochromocytoma

To determine the diagnostic performance of apparent diffusion coefficient (ADC) histogram analysis in diffusion‐weighted (DW) magnetic resonance imaging (MRI) for differentiating adrenal adenoma from pheochromocytoma.

Amide Proton Transfer Imaging of Cavernous Malformation in the Cavernous Sinus

Amide proton transfer (APT) imaging is an emerging molecular MRI technique based on chemical exchange saturation transfer where the imaging contrast is generated by endogenous mobile proteins and peptides. Previous studies have shown that APT signal increases with increasing malignancy grade of gliomas, hypothetically reflecting abundant cytosolic protein due to high cellularity. Cavernous malformation is rare, highly vascular benign lesion that has very low cellularity. Here, we report a cavernous malformation that showed markedly high APT signal. A 70-year-old woman presented with left facial discomfort and progressive loss of vision in the left eye for 6 months. Magnetic resonance imaging was performed using a 3T scanner (Ingenia 3.0T; Philips Healthcare, Best, The Netherlands) equipped with dual-source parallel radiofrequency transmission system and a 15-channel head coil for signal reception, which revealed a left cavernous sinus mass with hypointensity on T1-weighted imaging, marked hyperintensity on T2-weighted imaging, and strong homogenous enhancement after contrast injection (Fig. 1). Amide proton transfer imaging based on two-dimensional single slice single-shot turbo spin-echo technique was performed: TR, 4550 ms; TE, 4.8 ms; flip angle 90°; turbo factor 128; number of signal averaging, 1; FOV, 230 × 230 mm2; imaging matrix, 128 × 128 (reconstructed in 256 × 256); slice thickness, 5 mm. A quasi-continuous saturation pulse with an amplitude of 2 μT and a duration of 2 s (40 × 50 ms, sin c-Gaussian elements) was applied at 27 offset frequencies including 24 ranging from +6 to −6 ppm with a step of 0.5 ppm and 2 at ±9.6 ppm as well as one far off-resonance frequency (−1560 ppm) for signal normalization. During postprocessing, the B0 field inhomogeneity was corrected on a voxel-by-voxel basis using a separately obtained map of B0. The APT images were obtained by calculating the magnetization transfer ratio asymmetry (MTRasym) between ±3.5 ppm using the B0-corrected MT-spectrum:

Whole-tumor apparent diffusion coefficient (ADC) histogram analysis to differentiate benign peripheral neurogenic tumors from soft tissue sarcomas: Differentiation of BPNSTs From STSs

Apparent diffusion coefficient (ADC) histogram analyses have been used to differentiate tumor grades and predict therapeutic responses in various anatomic sites with moderate success.

Amide proton transfer imaging of tumors: theory, clinical applications, pitfalls, and future directions

Amide proton transfer (APT) imaging is an emerging molecular magnetic resonance imaging technique based on chemical exchange saturation transfer (CEST). APT imaging has shown promise in oncologic imaging, especially in the imaging of brain tumors. This review article illustrates the theory of CEST/APT imaging and describes the clinical utility, pitfalls, and potential for future development of APT imaging.

Extracellular volume fraction determined by equilibrium contrast-enhanced multidetector computed tomography as a prognostic factor in unresectable pancreatic adenocarcinoma treated with chemotherapy

ObjectivesTo assess whether extracellular volume (ECV) fraction with equilibrium contrast-enhanced multidetector computed tomography (MDCT) predicts outcomes for unresectable pancreatic adenocarcinoma patients treated with chemotherapyMethodsSixty-seven patients (42 men, 25 women; mean age, 67.5 years; range, 45–83 years) with histologically confirmed surgically unresectable pancreatic adenocarcinoma underwent contrast-enhanced MDCT before systemic chemotherapy. Tumour contrast enhancement (CE) and ECV fraction were calculated using region-of-interest measurement within the pancreatic adenocarcinoma and aorta on unenhanced and equilibrium phase-enhanced CT. The effect on survival variables including age, sex, tumour location, tumour size, TNM stage, carbohydrate antigen (CA) 19-9, carcinoembryonic antigen (CEA), tumour CE and tumour ECV fraction was determined on univariate and multivariate analyses using Cox proportional hazards regression model.ResultsMedian overall survival was 10.5 months. On univariate analysis, elevated serum CA19-9 (hazard ratio (HR), 1.00; p = 0.006) and CEA (HR, 1.02; p = 0.011) levels were found to be associated with a negative effect on overall survival. Increasing tumour CE (HR, 0.98; p < 0.001) and ECV fraction (HR, 0.97; p = 0.001) were associated with a positive effect. Multivariate analysis revealed that only tumour ECV fraction was an independent predictor of overall survival (HR, 0.97; p = 0.012).ConclusionsECV fraction with equilibrium contrast-enhanced MDCT could be a useful imaging biomarker for predicting patient survival after chemotherapy for unresectable pancreatic adenocarcinoma.Key Points• Tumour aggressiveness and response to therapy are influenced by the extravascular extracellular space.• Extracellular volume (ECV) fraction can be quantified with equilibrium contrast-enhanced CT.• Patients with higher tumour ECV fraction had better prognosis after chemotherapy.

Computed diffusion-weighted MR imaging for visualization of pancreatic adenocarcinoma: Comparison with acquired diffusion-weighted imaging

OBJECTIVE To assess the feasibility of computed diffusion-weighted imaging (cDWI) in comparison with directly acquired DWI for visualizing pancreatic adenocarcinomas. MATERIALS AND METHODS Patients with pancreatic adenocarcinoma underwent DWI at b-values of 0, 1000 (DWI1000), 1500 (DWI1500) and 2000 (DWI2000) s/mm2. From DWIs at b-values of 0 and 1000s/mm2, we generated cDWIs at b-values of 1500 (cDWI1500) and 2000 (cDWI2000) s/mm2. DWI findings of pancreatic adenocarcinomas (clear hyperintensity; hyperintensity with an unclear distal border; and isointensity), the image quality and the tumor to pancreas contrast ratio (CR) were compared between directly acquired DWI and cDWI. RESULTS Among the 63 included patients, clear hyperintense tumors were seen in 35 on DWI1000, 50 on DWI1500, 50 on cDWI1500, 53 on DWI2000 and 44 on cDWI2000. Incidence of clear hyperintense tumors was significantly higher on cDWI1500 than on DWI1000 (P=0.013). There was no significant difference in the incidence of clear hyperintense tumors between DWI1500 and cDWI1500 (P>0.999), but a lower incidence was seen on cDWI2000 than on DWI2000 (P=0.028). Image quality was lower on cDWI than on DWI at b-values of 1500 (P=0.002) and 2000s/mm2 (P<0.001). The tumor to distal pancreas CR was significantly higher on cDWI2000 than on cDWI1500 (P<0.001), and on cDWI1500 than on DWI1000 (P<0.001). The cDWI showed a significantly higher tumor to distal pancreas CR than DWI at b-values of 1500 (P=0.004) and 2000s/mm2 (P<0.001). CONCLUSIONS cDWI1500 generated from b-values of 0 and 1000s/mm2 should be considered more effective than DWI1000 and at least as effective as DWI1500.

Bilateral Tibial Osteofibrous Dysplasia on 18F-FDG PET/CT

A 17-year-old girl had pain in the right front lower leg while road racing 2 months earlier. Radiography and CT showed osteolytic lesions in the medial part of the bilateral tibia. Bone scintigraphy showed focally increased radiotracer uptake in the bilateral tibia. The lesions showed hypermetabolism on FDG PET/CT. Osteofibrous dysplasia was suspected from the radiographic findings, but adamantinoma or metastases could not be excluded. Surgical biopsies were performed, and histopathologic studies confirmed the diagnosis of bilateral osteofibrous dysplasia.