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Biomedical subjects

Junichi Hachiya

Publications and source records attributed to Junichi Hachiya.

At least 19 recordsLinked to original sources
PubMed2005

Anorectal malignant melanoma: preoperative usefulness of magnetic resonance imaging.

Magnetic resonance imaging (MRI) findings in three patients with primary anorectal malignant melanoma are described. Two patients had melanotic and one had amelanotic anorectal melanoma. The findings of MRI with a pelvic coil and an endorectal coil were consistent with pathologic findings. MRI with a pelvic coil demonstrated the melanotic component as high signal intensity on T1-weighted imaging. MRI with a pelvic coil and an endorectal coil was useful for staging anorectal melanoma. This article describes the initial report of the use of an endorectal coil for malignant melanoma of the anorectum.

Adult↗
PubMed2004

Three-dimensional MR digital subtraction angiography using parallel imaging and keyhole data sampling in cerebrovascular diseases: initial experience.

We assessed the feasibility of MR digital subtraction angiography (DSA) using parallel imaging and keyhole data sampling in the diagnosis of cerebrovascular diseases (CVDs) in 11 patients. Their diseases included arterial trunk stenosis/occlusion ( n=4), aneurysm ( n=3), arteriovenous malformation ( n=2), venous angioma ( n=1), and sinus thrombosis ( n=1). The technique depicted not only anatomical features, comparably to MR angiography ( n=10/11), but also hemodynamics such as collateral flow at a temporal resolution of 1.68 s/frame. When compared with conventional angiograms ( n=7), details were missed in four patients (incomplete demonstration of aneurysmal neck in two and poor separation of AVM components in two). Although inferior to conventional angiography, this technique can provide both anatomical and hemodynamic information of CVDs.

Adolescent↗
PubMed2004

Diffusion-weighted MR imaging in acute spinal cord ischemia.

We report diffusion-weighted (DW) MR findings for acute spinal cord ischemia in a 56-year-old patient. MR imaging obtained approximately 3 h after symptom onset demonstrated an area of hyperintensity on DW images, but no conspicuous signal abnormality on T2-weighted images in the conus medullaris. DW imaging of the spinal cord can contribute to the early detection of spinal cord vascular compromise.

Acute Disease↗
PubMed2004

MR digital subtraction angiography with three-dimensional data acquisition in the diagnosis of brain tumors: preliminary experience.

MR digital subtraction angiography (DSA) visualizes intracranial vasculature using a rapid T1-weighted sequence and a bolus injection of gadolinium. Although two-dimensional sequences are most frequently used, we applied a three-dimensional technique in combination with a fast method of k-space filling to improve both the temporal and spatial resolutions. In this preliminary study, we assessed the feasibility of using this technique for the diagnosis of brain tumors in 21 patients by reviewing the obtained images and, in 10 patients, comparing the images with conventional angiograms. MR DSA visualized a tumor stain in 11 patients, a tumor mass effect in 9, and tumor-related vessels in 5. In 9 of the 10 patients for whom conventional angiograms were available, the two kinds of angiograms corresponded well. Three-dimensional MR DSA using our technique is a useful adjunct to conventional MR imaging for the visualization of tumor hemodynamics and, in some cases, tumor-related vessels and mass effects.

Adolescent↗
PubMed2003

Evaluation of MR cisternography of the cerebellopontine angle using a balanced fast-field-echo sequence: preliminary findings.

We evaluated the feasibility of MR cisternography by the balanced fast-field-echo (bFFE) sequence, comparing with that by a turbo-spin-echo (TSE) sequence, for cerebellopontine angle lesions on a 1.5-T imager (Gyroscan Intera, Philips, Best, The Netherlands). The bFFE MR cisternograms depicted target cranial nerves with less cerebrospinal fluid pulsation artifacts than TSE cisternograms and visualized an acoustic schwannoma in 6 of 44 patients with suspicion and a causative vessel of hemifacial spasm in all of 3 patients in a short scanning time (1 min 53 s). The bFFE sequence can be promising for MR cisternography in the diagnosis of cerebellopontine angle lesions.

Adolescent↗
PubMed2003

The pearl necklace sign: an imaging sign of adenomyomatosis of the gallbladder at MR cholangiopancreatography.

PURPOSE: To evaluate the demonstration of the pearl necklace sign at magnetic resonance (MR) cholangiopancreatography (MRCP) in patients with proven adenomyomatosis and carcinoma of the gallbladder. MATERIALS AND METHODS: MRCP findings and those of a combination of unenhanced and arterial phase computed tomography (CT) and arterial phase MR imaging were retrospectively compared in 29 patients who were pathologically proven to have adenomyomatosis of the gallbladder and in 18 patients with pathologically proven gallbladder carcinoma. Receiver operating characteristic (ROC) analysis was used with a five-point confidence scale. The relative sensitivity, specificity, and accuracy of each imaging modality were also calculated. The pearl necklace sign was defined on MRCP images as small round foci, with the same markedly high signal intensity as bile, within the thickened wall of the gallbladder. RESULTS: The mean area under the ROC curve of MRCP alone and that of the combination of MRCP and arterial phase MR imaging was significantly higher than that of combined CT (unenhanced and arterial phase) and arterial phase MR imaging alone (P <.01). The relative sensitivities in the diagnosis of adenomyomatosis of the gallbladder were 24% for the combined CT, 29% for arterial phase MR imaging, 62% for MRCP, and 57% for the combination of MRCP and arterial phase MR imaging. The mean relative sensitivity, specificity, and accuracy of the pearl necklace sign on MRCP images were 62%, 92%, and 74%, respectively. In eight (28%) of 29 patients with adenomyomatosis of the gallbladder, the pearl necklace sign was not identified by all three readers on the MRCP images. CONCLUSION: The pearl necklace sign, which indicates the presence of Rokitansky-Aschoff sinuses within the thickened gallbladder wall, was specifically detected at MRCP for adenomyomatosis of the gallbladder.

Adenomyoma↗
PubMed2003

Magnetic resonance cholangiopancreatography for postoperative follow-up of intraductal papillary-mucinous tumors of the pancreas.

BACKGROUND: After resection of an intraductal papillary-mucinous tumor (IPMT), benign tumors or portions of the resected tumor are sometimes left in place to avoid total pancreatectomy. We evaluated the role of magnetic resonance cholangiopancreatography (MRCP) in postoperative follow-up. METHODS: Twenty-two patients underwent MRCP 0.5 to 6.5 years after pancreatic resection for IPMT. RESULTS: Two patients with surgical margin involvement of the main pancreatic duct showed mildly enhanced ductal dilatation due to anastomotic stenosis. In 4 patients with residual IPMT of the branch ducts, postoperative MRCP demonstrated no changes. MRCP revealed new IPMT 1 year after surgery in 1 patient. No patients showed intraductal or intracystic mural nodules postoperatively. In 3 patients with postoperative pancreatitis or recurrent abdominal discomfort, MRCP demonstrated ductal dilatation and poor secretin-stimulated pancreatic secretion into the gastrointestinal tract, which suggested pancreatoenterostomic stenosis. CONCLUSIONS: MRCP is useful for postoperative follow-up of IPMT, in terms of investigating residual or recurrent IPMT and evaluating postpancreatectomy long-term complications.

Aged↗
PubMed2003

Comparison between endorectal coil and pelvic phased-array coil magnetic resonance imaging in patients with anorectal tumor.

BACKGROUND: Magnetic resonance imaging (MRI) has been used as one of the diagnostic tools in the preoperative evaluation of rectal cancer. However, the usefulness of endorectal coil (ERC) compared with phased array coil (PA) MRI is still unknown. PATIENTS AND METHODS: Nineteen patients with rectal (17 patients) and anal (2 patients) tumors undergoing both ERC-MRI and PA-MRI preoperatively were included in the study. Seventeen patients had advanced stage tumors, and the remaining 2 had early stage tumors. The diagnostic accuracy of depth tumor invasion and lymph node metastasis were compared with reference to the histopathologic findings as the gold standard. RESULTS: ERC-MRI was evaluable in only 10 (52.6%) of 19 patients, because of difficulties in ERC placement, whereas PA-MRI could be obtained in all patients (100%). In 10 patients examined by both modalities, the diagnostic accuracy of depth of tumor invasion was 80% by ERC-MRI and 80% by PA-MRI. In lymph node staging, ERC yielded sensitivity of 100%, specificity of 62.5%, and overall accuracy of 70.0%. The corresponding values for PA-MRI were 50%, 100% and 90.0%, respectively. These figures were not significantly different between the two modalities. CONCLUSIONS: ERC-MRI and PA-MRI showed similar diagnostic accuracy. ERC-MRI may be abandoned in the preoperative staging of patients with locally advanced anorectal tumors because of its limited clinical utility.

Adult↗
PubMed2003

A prospective comparison between multidetector-row computed tomography and magnetic resonance imaging in the preoperative evaluation of rectal carcinoma.

BACKGROUND: Multidetector-row computed tomography (MDCT, or multislice CT) is a new modality with four detectors, which makes examination time shorter and produces higher resolution and multiplanar reformation of the images. Its diagnostic role in patients with rectal carcinoma has not been determined. METHODS: Twenty-one patients with rectal carcinoma were preoperatively examined by both MDCT and magnetic resonance imaging (MRI). Diagnostic accuracies of both modalities were compared regarding depth of tumor invasion and lymph node metastasis based on the pathologic findings. RESULTS: Both examinations detected all tumors. Regarding depth of tumor invasion, the concordance was 95.2% (20 of 21) for MDCT and 100% (21 of 21) for MRI. Regarding lymph node metastasis, the overall accuracy was 61.9% for MDCT and 70.0% for MRI. CONCLUSIONS: Multidetector-row computed tomography was equal to MRI in the preoperative local staging of rectal carcinoma.

Adenocarcinoma↗
PubMed2003

MR digital subtraction angiography in the diagnosis of meningiomas.

OBJECTIVE: MR digital subtraction angiography (DSA) is a technique for demonstrating the vasculature combining a rapid two-dimensional T1-weighted sequence with a bolus injection of gadolinium. We attempted to determine its contribution to the diagnosis of intracranial meningiomas. METHODS AND PATIENTS: MR DSA was performed in 18 patients with meningioma as well as in 28 patients with other tumors. The findings were analyzed regarding demonstration of tumor stain and tumor-related vessels. RESULTS: All meningiomas except one were visualized as a homogeneous and intense stain. Feeding arteries were visualized in 2 patients, and draining or abnormal veins in three. In 21 of the 28 patients with other tumors, tumor stains of varying degrees were demonstrated. CONCLUSION: MR DSA can serve as an adjunct to routine MR imaging, because it enables assessment of the hemodynamics of meningiomas and facilitates its differential diagnosis from other tumors.

Adolescent↗
PubMed2003

[Dose investigation of superparamagnetic iron oxide (SPIO) SH U 555 A in liver MR imaging].

SH U 555 A, a new superparamagnetic iron oxide (SPIO) contrast agent for liver MR imaging, was investigated in terms of safety and efficacy. Eighty-four patients with suspected malignant liver tumor were randomly allocated to two groups: the L dose group (8 mumol Fe/kg) and H dose group (12 mumol Fe/kg). Efficacy was qualitatively evaluated through blinded reading of the MR images. Assessment of the images revealed no consistent differences between the L and H dose groups. During the 3- to 4-day observation period, a total of 16 adverse events were observed in 11 patients: 8 patients in the L dose group and 3 patients in the H dose group. Nasal bleeding occurred in 2 of these cases in the H dose group 2 and 4 days, respectively, after injection. Although patients in the H dose group showed a significantly larger transient decrease in Coagulation Factor XI at 4-6 hr post-injection (p.i.) than patients in the L dose group, analysis of covariance revealed an estimated 6.5% difference. There was no prolongation of APTT or change in Factor XI at 72-96 hr p.i. Because there were no clinically significant differences between the L and H doses, both were considered to be safe and effective.

Aged↗
PubMed2002

Application of multi-detector row helical scanning to postmyelographic CT.

The advent of a multi-detector row helical CT has made it possible to attain images over a broader area with good spatial resolution. We assessed whether postmyelographic CT scans obtained using this system provided more information than conventional imaging techniques. Postmyelographic CT scans were preoperatively obtained in 46 patients using a multi-detector row helical CT system. Reconstructed images in the sagittal and coronal planes in all patients and curved reformation images along the dural sac in 37 patients were compared with myelograms and conventional postmyelographic CT scans. In 34 patients comparison was also made with MR images. The multi-detector row CT images demonstrated deformities of the dural sac more clearly than the other modalities in 39 of the 46 patients. They also provided the best visualization of nerve root abnormalities in 24 of the 46 patients and clearly revealed the presence of spurs in all 22 patients with spinal canal stenosis. Postmyelographic CT scans made using a multi-detector row helical CT system provide more information on the dural sac, nerve sleeves, and their contents than other imaging techniques.

Adolescent↗
PubMed2002

MR-angiogram-added surface anatomy scanning of superficial cerebral arteriovenous malformations.

Our purpose was to evaluate the utility of surface anatomy scanning (SAS) of the brain with superimposition of MR angiograms in the diagnosis and presurgical planning of superficial cerebral arteriovenous malformations (AVMs). We performed SAS in 15 patients with superficial cerebral AVMs. Two-dimensional phase-contrast MR angiograms were then obtained in the same section and superimposed on the SAS images. The images were assessed regarding the visualization of each AVM component using a four-point grading scale (3=excellent to 0=poor). In 13 of the patients, the assessment was made comparing with conventional angiograms. The images were also compared with the surgical findings in 5 patients. The added images agreed well with the angiographic findings and demonstrated the relationships between the AVM components and the adjacent brain surface. The average scores of the feeder(s), nidus, and drainer(s) were 2.27, 2.33, and 2.67, respectively. The surgical findings also correlated well with the added images. Our technique can noninvasively demonstrate superficial AVMs along with the brain surface and provide information useful for planning surgery.

Adult↗
PubMed2002

Preoperative evaluation by magnetic resonance imaging in patients with bowel obstruction.

BACKGROUND: Bowel obstruction is a problematic condition because the main clinical issue is to determine whether emergency laparotomy or observation with a long tube is required. The recent development of imaging diagnostic modalities such as magnetic resonance imaging (MRI) is thought to be promising to support therapeutic decisions in patients with bowel obstruction. METHODS: Twenty-seven patients with bowel obstruction who underwent laparotomy were evaluated by plain x-ray film, computed tomography (CT) scan, and MRI preoperatively with regard to the presence or absence of bowel obstruction, and the site and cause of bowel obstruction. Diagnostic accuracies were compared among these radiological modalities. RESULTS: The presence of bowel obstruction was detected in 22 (81.5%) of 27 patients by plain abdominal x-ray film, in 24 (92.3%) of 26 patients by CT scan, and in 25 (92.6%) of 27 patients by MRI. The sites of obstruction were consistent with surgical findings in 25 (92.6%) of 27 patients by MRI, and in 15 (57.7%) of 26 patients by CT scan. The causes of bowel obstruction were accurately diagnosed by MRI in 25 (92.6%) of 27 patients, and in 23 (88.5%) of 26 patients by CT scan. CONCLUSIONS: MRI could identify the presence and the site and cause of bowel obstruction in most of the cases. MRI is assumed to be superior to CT scan in the preoperative diagnosis of bowel obstruction.

Adult↗
PubMed2002

Preoperative staging by multidetector-row computed tomography in patients with rectal carcinoma.

BACKGROUND: Multidetector-row computed tomography (MDCT, or multi-slice CT) has been introduced in 2000. So far, there has been no published study on this modality in patients with rectal carcinoma. METHODS: Twenty patients with rectal carcinoma were preoperatively examined by MDCT and conventional CT (CCT). Diagnostic accuracies of both modalities were compared regarding the evaluation of depth of tumor invasion (Tis/T1/T2, T3, T4) and lymph node metastasis based on the pathologic findings. RESULTS: Although CCT detected a tumor in 13 (65%) of 20 patients, MDCT revealed a tumor in all 20 patients (P = 0.004). Regarding depth of tumor invasion, the concordance rate was significantly higher for MDCT (20/20: 100%) than for CCT (12 of 20: 60%; P = 0.002). Regarding lymph node metastasis, the overall accuracy was 70.0% in CCT, and also 70.0% in MDCT. CONCLUSIONS: MDCT was superior to CCT in the evaluation of depth of tumor invasion, but was equal to CCT in the evaluation of lymph node metastasis.

Adenocarcinoma↗
PubMed2002

[Japanese radiological report creation with continuous speech recognition].

Ten Japanese radiological reports consisting of 1381 characters (681 words) were created by two board-certified radiologists who used conventional typing and a continuous speech-recognition system called AmiVoice (Advanced Media, Inc., Tokyo, Japan). The two radiologists had not had any special training prior to their use of the continuous speech-recognition system. The model of speech-to-text analysis was generated from 22,589 radiological reports (5.7 MB). Dedicated pronunciations for loan words (i.e., English words) were registered by a board-certified radiologist in consideration of variations in Japanese pronunciation. Misrecognition occurred in 40 of 1362 words, corresponding to a 97.1% rate of accuracy of recognition. The average speech recognition time per report was 31.3 sec, and the additional time required for corrections was 25.0 sec. The total speech input time of 56.2 sec was much less than the conventional input time of 142.8 sec for typing. Continuous speech recognition is faster than typing, even considering the additional time required for corrections, and is acceptable in view of the overall reduction in report turn-around time.

Humans↗