[en] Contrast agents have come increasingly into use for MR angiography for the purpose of improving flow contrast. Three-dimensional gradient echo imaging can be performed during or after administration of the contrast agent, Gd-DTPA. In this article, we review pertinent current imaging techniques from both a basic and a clinical point of view. The importance of hemodynamic considerations relevant to contrast-enhanced MR angiography is stressed. (author). 58 refs

[en] The diagnostic accuracy of CT colonography (CTC) by 64-row multislice CT was evaluated. The detection rate was evaluated according to the size and gross morphology of the lesion in 275 lesions (≥2 mm) in 208 patients who underwent total colonoscopy and CTC on the same day. The sensitivity was 36.9% at a tumor size of 2 mm, 52.5% at 3 mm, 79.6% at 4 mm, 72.2% at 5 mm, and 100.0% at ≥6 mm. The positive predictive value was 76.5% for lesions 6 mm or larger. In elevated lesions, the sensitivity was 60.0% for Is (sessile), 100% for Isp (subpediculate) and 100% for Ip (pediculate), with a mean of 64.3%. In superficial lesions, the sensitivity was low, at 40% (4/10), for IIa (including laterally spreading tumor (LST)). Colon cancer could be detected by CTC in all 4 patients. Since the detection rate of lesions 6 mm or greater, which are treatment targets, by CTC was satisfactory, CTC may become a useful modality for colon cancer screening. (author)

[en] In recent years, CTC (CT colonography) has been clinically applied in the screaning of colorectal cancers, and is regarded highly for its diagnostic accuracy. This has become possible because of widespread use of multi-slice CT and increased use of analysis software. In addition, CTC, which yields objective and reproducible results, is a high-potential screening method, in that it is a low-invasive test associated with only mild distress, and can be easily normalized. In this center, screening for colorectal cancers with CTC is being conducted, with its accuracy being proved by statisical data: sensitivity (91.4%), specificity (92.4%), positive predictive value (PPV) (69.6%), negative predictive value (NPV) (98.3%), proper diagnosis rate (92.3%), and rate of detecting cancer (0.21%). CTC is considered to have the potential to become a 'new test for colorectal cancers', and can play an important role in screening for such cancers. (author)

[en] We evaluated quantitatively the enhancement pattern of the aorta, normal liver and liver tumor on dynamic helical CT and dynamic MRI. Triple-phase (arterial, portal and delayed phase) dynamic helical CT and MRI of the whole liver were obtained in 22 patients with hepatocellular carcinoma, 15 patients with hemangioma and 26 patients with metastatic tumors. We calculated the contrast index defined as division of enhancement value at a certain time by peak enhancement value, and contrast enhancement ratio (CER) on a CT value and MR signal intensity of tumors on each phase. The enhancement pattern of liver tumors was similar to that of normal structure. But it significantly differed on the delayed phase. After the peak of the enhancement, the enhancement of both the aorta and liver parenchyma lasted on dynamic MRI longer than that of dynamic helical CT. The contrast index of the hepatocellular carcinoma was the highest on arterial phase on both CT and MRI. Tumor became isointensity on the delayed phase with dynamic MRI, while wash-out of contrast material was seen on CT. The contrast index of hemangioma was greatest on the delayed phase MRI. On delayed phase MRI, metastatic tumors became isointensity. (author)

[en] Echo planar imaging is a very fast imaging technique that allows one to collect all the data required to reconstruct an image in a less than 100 ms. We undertook this study to evaluate EPI pulse sequence performance in the application of imaging of liver neoplasms. Three EPI pulse sequences (short TE SE-EPI, long TE SE-EPI and short TE GE-EPI) were obtained in 25 patients (35 lesions) with liver neoplasms. The signal-to-noise ratio of liver and tumor were highest on GE-EPI, while liver-tumor contrast was better on long TE SE-EPI. In 16 of 35 lesions, liver-tumor contrast was better on SE-EPI than on breath-hold TSE images and equal in 15 of 35 lesions. (author)

[en] We successfully performed embolization therapy for a pelvic arteriovenous malformation by the retrograde transvenous approach using a liquid embolie material. This malformation was unique in that it had a single draining vein, which allowed this technique employing an occlusion balloon.

[en] We successfully performed embolization therapy for a pelvic arteriovenous malformation by the retrograde transvenous approach using a liquid embolic material. This malformation was unique in that it had a single draining vein, which allowed this technique employing an occlusion balloon

[en] Background: Although the screening of small, flat polyps is clinically important, the role of CT colonography (CTC) screening in their detection has not been thoroughly investigated. Purpose: To evaluate the detection capability and usefulness of CTC in the screening of flat and polypoid lesions by comparing CTC with optic colonoscopy findings as the gold standard. Material and Methods: We evaluated the CTC detection capability for flat colorectal polyps with a flat surface and a height not exceeding 3 mm (n = 42) by comparing to conventional polypoid lesions (n = 418) according to the polyp diameter. Four types of reconstruction images including multiplanar reconstruction, volume rendering, virtual gross pathology, and virtual endoscopic images were used for visual analysis. We compared the abilities of the four reconstructions for polyp visualization. Results: Detection sensitivity for flat polyps was 31.3 %, 44.4 %, and 87.5 % for lesions measuring 2-3 mm, 4-5 mm, and ≥6 mm, respectively; the corresponding sensitivity for polypoid lesions was 47.6 %, 79.0 %, and 91.7 %. The overall sensitivity for flat lesions (47.6%) was significantly lower than polypoid lesions (64.1%). Virtual endoscopic imaging showed best visualization among the four reconstructions. Colon cancers were detected in eight patients by optic colonoscopy, and CTC detected colon cancers in all eight patients. Conclusion: CTC using 64-row multidetector CT is useful for colon cancer screening to detect colorectal polyps while the detection of small, flat lesions is still challenging

[en] 

Purpose

To test the tagging efficacy, patient acceptability, and accuracy of computed tomographic colonography (CTC) with a reduced dose of laxative using a novel barium sulfate (BaSO₄) contrast agent.

Materials and methods

CTC followed by optical colonoscopy (OC) was performed on 73 patients with positive results in fecal occult blood tests. They were administrated a BaSO₄ suspension and a magnesium citrate solution for bowel preparation. Patients completed a questionnaire about the acceptability of bowel preparation. Tagging efficacy was estimated using a novel categorization system, which classified all segments into 8 categories. The accuracy of detecting protruded lesions ≥ 6 mm was calculated from the comparison of CTC and OC results, using the latter as a reference standard.

Results

Tagging efficacy was good in 77.3% of colonic segments where residue was observed. The acceptability of bowel preparation for CTC was significantly higher than that for OC. The sensitivity, specificity, and positive and negative predictive values were 0.778, 0.945, 0.824, and 0.929, respectively. All lesions ≥ 7 mm were successfully detected by CTC.

Conclusion

CTC with a reduced dose of laxative using a novel BaSO₄ contrast agent has a favorable tagging efficacy, patient acceptability, and accuracy.