Purpose: The purpose of this study was to assess the potential role of diŠusion-weighted imaging (DWI) using low and high b-values to detect rectal cancer.Methods: The subjects were 15 patients diagnosed endoscopically with rectal cancer (m in 1 patient, sm in 0, mp in 3, ss in 7, se in 1, a in 3) and 20 patients diagnosed endoscopically with colon cancer and no other lesions (control group). Magnetic resonance imaging was performed using a 1.5T system. DWI was performed in the axial plane using echo planar imaging sequence (repetition time W echo time 1200 W 66,ˆeld of view 306×350 mm, reconstruction matrix 156×256, pixel size 2.0×1.4×8.0 mm) and acquired with 2 b-values (50 and 800 s W mm 2 ). Low and high b-value DW images were analyzed visually. A lesion was positive by detection of a focal area of high signal in the rectum in high b-value images. The apparent diŠusion coe‹cient (ADC) values of areas of high signal in high b-value images were calculated from the low and high b-value images.Results: High b-value images enabled visualization of all 15 rectal cancers. In the control group, 13 cases were classiˆed as negative and 7 cases as positive for rectal cancer. Sensitivity for detection of rectal cancer was 100z (15 W 15), and speciˆcity was 65z (13 W 20). The mean ADC values in 7 patients with false-positive lesions and in 15 patients with rectal cancer were 1.374×10 -3 mm 2 W s (standard deviation [SD]: 0.157) and 1.194×10 -3 mm 2 W s (SD: 0.152), respectively (P＝0.026).Conclusion: DWI with low and high b-values may be used to screen for rectal cancer.

A 50-year-old male with hepatitis B was referred for a small intrahepatic nodule. Magnetic resonance images raised strong suspicion of a benign lesion, such as an inflammatory pseudotumor, while the other radiological studies were equivocal. Furthermore, the high-intensity image on diffusion magnified-weighted imaging with a low B value strongly suggested a benign tumor. In spite of the absence of typical clinical or radiological findings, needle biopsy revealed an intrahepatic cholangiocarcinoma (ICC). The diagnosis of peripheral ICC rich in fibrous tissue seems to require needle biopsy for pathological examination with immunohistochemical staining because it frequently mimics other diseases, including benign tumors.

Reported herein is a gastric leiomyosarcoma, which, nowadays, is extremely rare. Attention was focused not only on pathological findings but also on the histological basis of magnetic resonance imaging (MRI) findings. The patient was a 29-year-old Japanese woman. Preoperative T2-weighted MRI showed a large high-intensity gastric tumor with isointense streaks. The tumor was a broad-based large polypoid lesion and histologically consisted of fascicles of spindled cells having eosinophilic cytoplasm and cigar-shaped nuclei. Immunoreactivity for several smooth muscle markers including desmin on tumor cells, low amplification of both c-kit and PDGFRA cDNA on polymerase chain reaction, and absence of c-kit gene mutation in exons 9 and 11 strongly suggested that the tumor was not a gastrointestinal stromal tumor but a true leiomyosarcoma. In vitro MRI of the fresh tumor was obtained to explain the radiological findings on a morphological basis. In vitro MRI clearly depicted the very high-intensity areas separated by radially extended isointense lines. This radiological finding corresponded best to the most characteristic histological feature, that is, linearly extended fascicles of the tumor cells often with myxedematous change separated by radially elongated thin fibrovascular stroma: in other words, spouting appearance.

The objective of this study was to evaluate the usefulness of the nonenhanced 3-dimensional heavily T2-weighted images obtained with 2-dimensional prospective acquisition and correction in visualization of the lymphatic system of the trunk. The thoracic duct, cisterna chyli, and lumbar lymphatics were well shown in 9 healthy volunteers. This nonenhanced magnetic resonance lymphoductography is thought to be a suitable method in visualization of the lymphatic system of the trunk.

A combination of morphologic criteria and kinetic information is useful for differentiating between benign and malignant SPNs. In particular, internal enhancement with PE and positive visual washout is thought be a useful tool.