Biomedical subjects

Junichi Hachiya

Publications and source records attributed to Junichi Hachiya.

23 records · Page 2Linked to original sources

PubMedDate not supplied

Visualization of extracranial-intracranial bypass using multidetector-row helical computed tomography angiography.

PURPOSE: The advent of multidetector-row computed tomography (MDCT) has enabled images with good spatial resolution to be obtained over a wide range in a short scanning time. Our purpose was to determine whether CT angiography using the MDCT system could effectively depict extracranial-intracranial (EC-IC) bypass routes. METHOD: Helical CT angiography was performed using an MDCT scanner in 12 patients who had undergone EC-IC bypass surgery: 10 patients had undergone superficial temporal artery-middle cerebral artery (MCA) anastomosis, 1 patient had undergone an encephaloduroarteriosynangiosis procedure for the treatment of moyamoya disease, and 1 patient had undergone an external carotid artery-MCA anastomosis using a graft. The resulting CT angiograms were visually evaluated for their depiction of the EC-IC bypass route. Conventional angiograms were available for comparison in all 12 patients. RESULTS: The EC-IC bypass was visualized to be patent at the site of anastomosis in all 12 patients. Branches of the MCA secondary or more to those connected to a donor artery were demonstrated in 9 patients, whereas MCA branches immediately distal to the anastomosis were demonstrated in 3 patients. The CT angiography findings corresponded well with the conventional angiography findings in all patients. CONCLUSION: Helical CT angiography using the MDCT technique is an effective method for visualizing EC-IC bypass routes.

Adult↗

PubMedDate not supplied

Case report: spinal cord infarction demonstrated on diffusion-weighted MR imaging with a single-shot fast spin-echo sequence.

We describe the diffusion-weighted (DW) MR imaging findings in three cases of spinal cord infarction using a recently developed single-shot fast spin-echo (SSFSE) technique. The SSFSE-DW MR images, which were obtained 20 hours, 3 days, and 18 days, respectively, after the ischemic event, demonstrated conspicuous areas of hyperintensity in the affected portions. Follow-up DW MR images, obtained in two of the patients at 17 days and 3 months, respectively, showed persistent decreased apparent diffusion coefficient values. SSFSE-DW imaging of the spinal cord may provide additional information for assessment of ischemic changes.

Aged↗

PubMedDate not supplied

Gadolinium enhanced endorectal coil and air enema magnetic resonance imaging as a useful tool in the preoperative examination of patients with rectal carcinoma.

BACKGROUND/AIMS: In the present study, we attempted to evaluate the usefulness of gadolinium enhanced endorectal coil and air enema magnetic resonance imaging with slice adjustments in patients with rectal carcinoma. METHODOLOGY: The subjects were patients with rectal cancer from June 1997 to September 1999 who were examined with a 1.5 Tesla magnetic resonance device. Buscopan was administered both intravenously and intramuscularly to reduce motion artifacts. Imaging sequences were obtained for T1 weighed, T2 weighed and T2 fat-saturated images. Slice thickness was 5 mm and interslice gap 3 mm. Endorectal coil insertion and air enema technique were performed with slice adjustments. Images were interpreted according to the criteria of the TNM classification. Lymph node metastasis was diagnosed as positive when the lymph nodes exceeded 5 mm in diameter. Histological and magnetic resonance findings were compared, and diagnostic accuracy was calculated. RESULTS: Fifty-four consecutive patients were included in this study (37 male, 17 female). There were 10 early cases and 44 advanced cases of rectal cancer. Images with an endorectal coil were obtained in 4 patients. Fifty patients underwent air enema technique. The depth of tumor invasion was accurately diagnosed in all 4 patients undergoing endorectal coil examination. On air enema study, magnetic resonance imaging correctly staged the depth of invasion in 41 of 50 patients (82.0%). Overstaging was seen in 8 of 50 patients (16%), however, only one patient (2.0%) was understaged. Overall accuracy, overstaging and understaging rates were 83.3% (45/54), 14.8% (8/54), and 1.8% (1/54), respectively. On endorectal coil study, accurate diagnosis of lymph node metastasis was obtained in 3 of 4 (75.0%) patients. On air enema study, an accurate diagnosis of lymph node metastasis was obtained in 36 of 50 (72.0%) patients, yielding 75.0% sensitivity and 73.1% specificity. Overall magnetic resonance imaging findings of lymph node metastasis resulted in 72.2% (39/54) diagnostic accuracy, yielding sensitivity of 75.0% (18/24) and specificity of 73.3% (22/30). CONCLUSIONS: We conclude that gadolinium enhanced endorectal coil and air enema magnetic resonance imaging is promising for preoperative evaluation of patients with rectal carcinoma.

Air↗

PubMedDate not supplied

Utility of cine MR urography of the urinary tract and comparison with static MR urography.

PURPOSE: MR urography using heavily T2-weighted images can depict the urinary tract without the need for contrast medium. However, this technique has potential problems with regard to evaluating the non-dilated ureter. We compared the efficacy of cine MR urography (C-MRU) with static MR urography (S-MRU). MATERIALS AND METHODS: Twenty-two patients with suspected upper urinary tract disease underwent C-MRU. The final clinical diagnosis was compared with the diagnosis made using S-MRU and C-MRU, respectively. The sequence used was single-shot fast spin echo with a slice thickness of 50 mm, FOV of 45 cm, and 256x256 matrix. MR urography was obtained sequentially by 6 to 10 repetitions of single-shot scans with intermittent breath holding. S-MRU was used in the initial phase of this sequence, while C-MRU was used for the entire sequence. A final diagnosis was made based on 1) existence of stenosis, 2) rate of certainty of existence of stenosis, 3) etiology of stenosis. RESULTS: No statistically significant difference was observed between S-MRU and C-MRU, except in certainty of existence of stenosis, where C-MRU (average rate: 2.82 +/- 0.39) was significantly superior to S-MRU (2.41 +/- 0.73). CONCLUSION: C-MRU can improve the certainty of existence of urinary stenosis, and may be useful in excluding suspected stenoses in normal or undilated ureters.

Adult↗

PubMedDate not supplied

MRI diagnosis of mesorectal lymph node metastasis in patients with rectal carcinoma. what is the optimal criterion?

BACKGROUND: Preoperative diagnosis of lymph node metastasis is often difficult. A number of different criteria have been advocated in the literature, however, an optimal criterion has not yet been determined in patients with rectal carcinoma. PATIENTS AND METHODS: Fifty-one patients, undergoing radical surgery with total mesorectal excision, were examined with reference to regional lymph node status. MRI and pathological findings were compared, and an optimal preoperative criterion was clarified by receiver operating characteristic (ROC) analysis. RESULTS: Among size, shape and internal structure criteria, size was a significant factor for diagnosing metastatic lymph node on MRI. ROC analysis showed that a criterion of 6-mm or larger in the longitudinal axis was the most reliable in differentiating metastatic and non-metastatic lymph nodes, with overall accuracy of 78%. CONCLUSION: A 6-mm longitudinal diameter criterion is thought to be most optimal in the evaluation of mesorectal lymph node status in patients with rectal carcinoma.

Female↗