Biomedical subjects

G Uchiyama

Publications and source records attributed to G Uchiyama.

At least 19 recordsLinked to original sources

PubMed1997

Giant calcifying epithelioma of Malherbe (pilomatrixoma): imaging features.

We present a case of giant calcifying epithelioma of Malherbe (pilomatrixoma) in the right upper arm of a 62-year-old man. It measured 18 x 12 x 8 cm in size, making it the largest of all the cases reported previously. CT clearly demonstrated a well-defined, subcutaneous mass with amorphous calcifications. The mass showed intermediate signal intensity on T2*-weighted MR images and slight contrast uptake on contrast-enhanced MR images. Histopathologically, this tumor showed no aggressive or malignant nature. The patient is without evidence of recurrence or metastasis 3 years following the resection.

Arm↗

PubMed1995

MRI of white matter changes in the Sjögren-Larsson syndrome.

We report a case of Sjögren-Larsson syndrome with spastic diplegia and conduction aphasia. MRI demonstrated the white matter changes deep in the cerebral hemispheres. We analyse the MRI findings and compare the results with neuropsychological signs.

Adolescent↗

PubMed1995

Contrast-enhanced dynamic MRI of adrenal masses: classification of characteristic enhancement patterns.

OBJECTIVE: This study evaluated the usefulness of dynamic MRI to differentiate various adrenal tumours. MATERIALS AND METHODS: Sixty-five adrenal tumours (28 adenomas, 22 metastases, seven phaeochromocytomas, five neurogenic tumours and three tuberculous granulomas) were evaluated with gadolinium-enhanced dynamic MRI (13 at 0.5 T, 52 at 1.5 T). In this technique, a series of 12 sequential images (gradient-echo images at 0.5 T and spin-echo images at 1.5 T) were obtained up to 21 min after bolus administration of 0.1 mmol/kg Gd-DTPA. RESULTS: All 28 adenomas showed peak enhancement in the early phase (< 2 min) and quick washout. Fourteen of 22 metastases showed peak enhancement in the early or middle phase (< 9 min) and slow washout. Six of seven phaeochromocytomas revealed marked peak enhancement in the early phase and little washout. All neurogenic tumours showed gradually increasing enhancement. Granulomas showed little enhancement. As a result, only 14 adrenal masses (27/65, 42%) were correctly classified according to contrast enhancement patterns. However, if we consider each type of enhancement pattern to be specific to adenoma, metastasis, phaeochromocytoma, neurogenic tumour and tuberculous granuloma respectively, 56 of the 65 adrenal masses (86%) could be classified. Seven of the indistinguishable nine tumours were performed at 0.5 T system using gradient-echo sequences. CONCLUSION: Dynamic MR imaging at 1.5 T is useful in the differentiation of adrenal masses. Imaging at 0.5 T with gradient-echo sequences seems less useful to distinguish adenomas from metastases.

Adenoma↗

PubMed1995

The usefulness and limitations of combined Tc-99m pertechnetate and Ga-67 citrate imaging of salivary gland disorders.

The usefulness of combined Tc-99m and Ga-67 scans in diagnosing salivary gland disorders was evaluated in a total of 31 patients. Out of 6 patients with Warthin's tumor, 4 showed a typical pattern of high-activity in the gland with retention of Tc-99m, but without an affinity for Ga-67. Out of 9 patients with pleomorphic adenoma, 8 showed a "cold" area in the tumor by Tc-99m and 5 of the 9 patients had accumulated Ga-67. Five of 6 patients with malignant tumor showed an affinity for Ga-67. Nine of 10 patients with sialadenitis showed diffuse uptake of both Tc-99m and Ga-67 in the involved gland. Combined Tc-99m and Ga-67 imaging was useful in detecting the cases of Warthin's tumor and sialadenitis (90% sensitivity and 89% specificity for sialadenitis), but the study had limitations in differentiating malignant tumors from benign tumors (66% sensitivity and 84% specificity). However, Ga-67 imaging showed a 91% negative predictive value. A negative scan could almost rule out the possibility of malignant disease of the salivary gland.

Adenocarcinoma↗

PubMed1995

Parameters of dynamic and static iodine-123-MIBG cardiac imaging.

UNLABELLED: Dynamic and static 123I-MIBG studies were used to investigate various parameters with regard to their usefulness in evaluating cardiac disorders. METHODS: Four patient groups and one control group were included in this study. Dynamic study was acquired immediately after injection at 1 frame/sec for 2 min and at 1 frame/6 sec for the next 30 min using a 64 x 64 matrix format. Static study consisted of planar images at the anterior and left anterior oblique 45 degrees views in a 512 x 512 matrix format for 1 min. The early and delayed planar images were acquired soon after dynamic acquisition and approximately 4 hr after injection, respectively. Net injection dose was calculated as the difference in syringe counts before and after injection. From the dynamic and static studies, the heart uptake ratios at 3 min and 30 min, early uptake ratio and delayed uptake ratio were calculated at various intervals. Early and delayed clearance rates, Ke and Kd, respectively were also determined. These parameters were compared and correlated with each other. RESULTS: Three-minute heart uptake ratios were significantly higher than early or delayed uptake ratios or uptake ratios at 30 min in all groups. All uptake ratios in hemodialysis patients were significantly higher than those in other groups. The Kd values in dilated cardiomyopathy, doxorubicin therapy and vasospastic angina patients were significantly higher than those in hemodialysis patients and normal controls. At least bi-exponential clearance patterns of MIBG from the heart were observed in all groups. CONCLUSION: Three-minute and delayed heart uptake ratios calculated from dynamic and static studies are helpful in elucidating the uptake at nonvesicular sites, which reflect the severity of sympathetic nervous system abnormalities in the heart.

3-Iodobenzylguanidine↗

PubMed1994

[Evaluation of malignancy and viability of brain tumors by 201Tl SPECT: the correlation between 201Tl SPECT and pathology, clinical progress and the intensity of enhancement on CT images].

Thallium-201 (201Tl) SPECT was performed 48 times in 26 patients to clarify its usefulness in the evaluation of malignancy and viability of brain tumors. The early counts ratio (ER) and delayed counts ratio (DR) of a lesion compared with normal brain were obtained 10-15 minutes and 3 hours, respectively, after intravenous administration of 185 MBq of 201Tl chloride. Untreated high grade malignant tumors and recurrent tumors did not always show high ER and DR, and they were widely distributed. High grade malignant tumors that showed low ER and DR were not well enhanced on CT or MRI. In low grade malignant tumors, such as pituitary adenoma which was well enhanced on CT, ER and DR were as high as in high grade malignant tumor. Whether a tumor recurred within three months after radiotherapy or not was retrospectively predicted at accuracy rates of 93.8% and 87.5% with cut-off points of 4.0 for ER and 3.5 for DR. Cerebral radiation necrosis showed ring-like increased uptake of 201Tl in proportion to the progress of necrosis and intensity of enhancement on MRI. In conclusion 201Tl SPECT is considered to be less useful for lesions that are well enhanced on CT, because they show high uptake of 201Tl regardless of their malignancy and viability. On the other hand, in tumors that are not well enhanced on CT. 201Tl shows good accumulation in viable and high grade malignant lesions. 201Tl SPECT should be performed in such cases.

Adult↗

PubMed1994

[Usefulness of superparamagnetic iron oxide particle (AMI-25) enhanced MR imaging for the diagnosis of liver tumors: comparison with contrast enhanced CT].

The purpose of this study was to clarify the usefulness of SPIO-enhanced MRI in the diagnosis of liver tumors in comparison with contrast-enhanced CT. The subjects were forty patients with 154 nodules in the liver. We compared SPIO-enhanced MRI with contrast-enhanced CT in terms of tumor-liver contrast and detectability of liver tumors. In terms of tumor liver contrast, SPIO-enhanced MRI was equal or superior to contrast-enhanced CT in 82% of cases. In the detectability of liver tumor, SPIO-enhanced MRI detected more tumors than contrast-enhanced CT, especially small tumors. Tumors undetected by SPIO-enhanced MRI that were detected by contrast-enhanced CT and/or plain MRI were adenomatous hyperplasia and inflammatory pseudotumor according to fine needle biopsy. There were no severe complications of SPIO-enhanced MRI. In conclusion, SPIO-enhanced MRI will be more useful than contrast-enhanced CT in the diagnosis of liver tumors. SPIO-enhanced MRI may be a promising diagnostic method for the detection of hepatic tumors, especially small ones.

Adult↗

PubMed1994

[Distinction between adrenal adenomas and metastases using 0.5 Telsa MR imaging: diagnosis with out-of-phase T2*-weighted gradient-field-echo image].

The purpose of this study was to investigate the ability of MR imaging with a 0.5-T apparatus to distinguish adrenal adenomas from adrenal metastases. The series included 23 adrenal adenomas (18 non-hyperfunctioning adenomas, 5 hyperfunctioning) and 23 adrenal metastases (14 from lung, 5 liver, 3 colon, and 1 stomach cancer). The signal intensity (SI) ratio (adrenal tumor/liver) on T1-, T2-, and T2*-weighted MR images was calculated for adrenal tissue characterization. Adrenal adenomas were more precisely distinguished from adrenal metastases on T2*-weighted images (21/23, 91%) than on T2-weighted images (15/23, 65%). In conclusion, T2*-weighted images were better than routine T2-weighted images in distinguishing adrenal adenomas from adrenal metastases. The reason could be that the total signal intensity of adrenal adenomas which contained some fat components decreased on T2*-weighted images due to an out-of-phase effect.

Adenoma↗

PubMed1994

Radioimmunoscintigraphy of CEA/CA 19-9 producing tumors with I-131 labeled monoclonal antibodies.

A total of 7 (4 males and 3 females) patients were included in this retrospective study to determine the sensitivity of radioimmunoscintigraphy with I-131 labeled anti CEA/CA 19-9 monoclonal antibodies. Out of 7 patients 2 had ascending colon cancer, one had sigmoid colon cancer, one had rectal cancer and one had adenocarcinoma in the CBD and the remaining two had metastatic tumor (one in the lungs and the other in the liver). Whole body as well as spot images showed a 72% (5/7) positive scan. But post operative specimen counts and imaging showed a high tumor to non-tumor ratio and a good tumor to non-tumor contrast of activity of I-131 labeled monoclonal antibody. We did not find any relation between CEA/CA 19-9 levels and scan findings. A case of liver metastasis was also detected by this radioimmunoscintigraphy.

Adenocarcinoma↗

PubMed1994

Scintigraphic changes in bone metastasis from prostate cancer after hormonal therapy--comparison with tumor markers and bone X-ray.

Bone scintigraphy is often performed to assess the response to systemic therapy of bone metastasis from prostate cancer. We examined the changes in bone scintigraphic findings and the agreement with AIP, AcP, or other tumor markers measured in the follow-up of patients with known bone metastasis after hormonal therapy. Out of 32 patients, 22 (69%) showed improved scintigraphic findings on the first follow-up bone scintigraphy after hormonal therapy. However, 7 out of 22 patients who showed improvement on the first follow-up scintigraphy, deteriorated thereafter. Changes in the scintigraphic findings were closely correlated with those in the measured tumor markers except for patients with small bone metastasis. Though there were no significant differences in the agreement ratios of the 6 tumor markers evaluated, AIP might be a practical and acceptable indicator. Bone X-ray findings did not change at all in almost half of the cases though the scintigraphic findings showed improvement or deterioration.

Acid Phosphatase↗

PubMed1994

Abdominal wall desmoid mimicking intra-abdominal mass: MR features.

A case of abdominal wall desmoid which enlarged toward the liver and mimicked an intra-abdominal tumor is presented. T*2-weighted MR images clearly demonstrated the tumor's continuity with the rectus abdominis muscle. The case presented suggests MRI may provide more valuable information concerning the origin of a right-upper-quadrant mass than CT does. However, the nature of the signals and attachment which this case showed were so unusual for desmoids that this case has not been diagnosed accurately.

Abdominal Muscles↗

PubMed1994

Adrenal adenomas: characteristic hyperintense rim sign on fat-saturated spin-echo MR images.

PURPOSE: To determine whether adrenal adenomas can be differentiated from metastases on fat-saturated magnetic resonance (MR) images. MATERIALS AND METHODS: Twenty-eight adrenal adenomas and 20 metastatic lesions were imaged at 1.5 T by means of fat-saturated T1- and T2-weighted and gadolinium-enhanced T1-weighted sequences. The authors evaluated visually whether structures of high signal intensity (hyperintense rim sign) could be observed in the outer margin of the adrenal masses. RESULTS: Twenty-six of 28 adrenal adenomas revealed the hyperintense rim sign on at least one kind of fat-saturated image, compared with only one of 20 metastases. The sensitivity of the hyperintense rim sign as suggestive of adrenal adenoma was 92%, specificity was 95%, and overall accuracy was 94%. CONCLUSION: The hyperintense rim sign is characteristic of adrenal adenomas. Thus, adrenal adenomas can be differentiated from metastases by means of this new imaging sign on fat-saturated MR images.

Adrenal Cortex Neoplasms↗

PubMed1994

Septa in the liver of patients with chronic hepatic schistosomiasis japonica: MR appearance.

OBJECTIVE: Chronic hepatic schistosomiasis japonica is a disorder characterized by broad fibrous septa in the liver. The ability to recognize these septa on MR images might enable distinction of this lesion from other cirrhotic disorders. The purpose of this study was to analyze the MR appearance of these septa. MATERIALS AND METHODS: MR images of 18 patients who had typical calcifications of hepatic septa on CT scans were reviewed. The diagnosis was proved by biopsy in six patients. In the remaining 12, stool examinations were positive for schistosomiasis. T1-weighted MR images and T2-weighted and intermediate (long repetition time and short echo time) MR images acquired with the use of gradient-moment nulling were obtained in all 18 patients. In eight of 18 patients, additional T2-weighted and intermediate images were obtained without gradient-moment nulling. Fifteen patients had contrast-enhanced T1-weighted images. The presence of abnormal MR signal and its intensity at sites corresponding to the septa seen on CT scans were studied. RESULTS: MR images showed the septa as linear abnormalities frequently seen in the subdiaphragmatic portion of the right lobe of the liver. On T1-weighted images, septa had low signal intensity and were identified in nine of 18 patients. On T2-weighted images obtained with gradient-moment nulling, septa had high signal intensity and were seen in 13 of 18 patients. On T2-weighted images obtained without gradient-moment nulling, the septa had primarily low signal intensity and were seen in five of eight patients. On intermediate MR images obtained with gradient-moment nulling, the septa had primarily high signal intensity and were seen in nine of 18 patients. On intermediate images obtained without gradient-moment nulling, the septa had primarily low signal intensity and were seen in four of eight patients. In nine of 15 patients, septa were visualized as high-signal-intensity lesions on contrast-enhanced T1-weighted images. In 14 of 18 patients, the septa were detected in one or more sequences. CONCLUSION: Our experience suggests that MR imaging in patients with chronic schistosomiasis of the liver depicts the morphologic features of hepatic septa. MR signal characteristics of septa are not unique, but use of gradient-moment nulling alters the signal intensity of septa, similar to that of blood vessels, on intermediate and T2-weighted images.

Aged↗

PubMed1994

[Functional parameters calculated by 99mTc-MAG3 in transplanted kidney].

A newly developed 99mTc-labeled renal tubular agent, 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) was evaluated and compared with 99mTc-DTPA and 123I-OIH in 10 patients with a transplanted kidney. Renal uptake of MAG3 correlated well with both DTPA and OIH; however, these uptake values of MAG3 were lower than those of OIH and higher than those of DTPA. Renogram parameters also correlated well with each other, but excretion of MAG3 was slower than that of OIH and faster than that of DTPA. The bladder to kidney ratio of MAG3 also correlated well, but these ratios of MAG3 were lower than those of OIH and higher than those of DTPA. In conclusion, MAG3 is a promising agent for evaluating the function of transplanted kidney.

Adult↗

PubMed1993

[Radiation stenosis and fistula formation developed after iridium-192 high-dose-rate intracavitary radiation boost therapy for carcinoma of the esophagus].

Intracavitary irradiation using a high-dose-rate Ir-192 remote after-loading system was applied to 14 advanced or inoperable patients with esophageal carcinoma as a boost therapy. The total dose of external irradiation was 45-70 Gy/15-35 fractions and that of intracavitary irradiation was 11.6-34.0 Gy/2-4 fractions at a point 5 mm deep from the inner surface of the esophageal mucosa. The time-dose-fractionation factor (TDF) of the whole treatment was 116-186 (mean, 146). Six patients (43%) had complete response (CR), three (21%) had partial response and five (36%) had no response. Esophageal carcinoma that showed exophytic growth, was less than 5 cm ling, and showed favorable response to external irradiation was likely to be a good candidate for intracavitary radiation boost therapy. Fistula formation was produced in five patients (36%), four of whom were irradiated at more than 140 TDF. All six CR patients were free from esophageal tumors, but severe esophageal stenosis due to radiation injury developed in five (83%) of them. They were irradiated at more than 135 TDF. One- and two-year survival rates were 28.6% and 14.3%, respectively. The poor prognosis was ascribed to the frequent occurrence of fatal radiation stenosis and fistula formation. An appropriate therapeutic dose for esophageal carcinoma that does not cause severe radiation stenosis was estimated to be under 120 TDF.

Aged↗

PubMed1993

Amyotrophic lateral sclerosis: T2 shortening in motor cortex at MR imaging.

PURPOSE: To determine whether decreased signal intensity of the motor cortex (T2 shortening) at magnetic resonance (MR) imaging is a useful finding for supporting the diagnosis of amyotrophic lateral sclerosis (ALS). MATERIALS AND METHODS: High-field-strength (1.5-T) MR images of 15 patients (seven men and eight women, aged 28-80 years) and 49 neurologically normal age-matched control patients were examined for T2 shortening in the motor cortex. In addition, brains of patients with ALS were examined at autopsy. RESULTS: The MR images of 14 of the 15 patients showed T2 shortening in precentral cortices, while the images of all but one of the control patients showed no such finding. In three of eight brains at autopsy, sections from the precentral cortex showed sparsely distributed, intensely stained astrocytes and macrophages. CONCLUSION: Abnormal iron deposition associated with the degenerative process could be the source of T2 shortening, which is a useful MR imaging finding in the diagnosis of ALS.

Amyotrophic Lateral Sclerosis↗

PubMed1993

Schistosomiasis japonica of the liver: contrast-enhanced CT findings in 113 patients.

OBJECTIVE: The purpose of this study was to determine the findings on contrast-enhanced CT scans in patients with hepatic schistosomiasis japonica and to determine their pathologic basis. MATERIALS AND METHODS: Unenhanced and contrast-enhanced CT scans of 113 patients with histologically proved schistosomiasis were reviewed. Radiologic and pathologic findings were correlated after autopsy in 19 patients. RESULTS: Unenhanced CT scans showed septal calcification in the liver parenchyma in 53 patients (47%) and capsular calcification along the hepatic surface in 29 patients (26%). Twenty-seven patients (24%) had both types of calcification. Fifty-four patients (48%) showed one or more types of enhancement. Septal enhancement (i.e., linear enhancement of hepatic parenchyma looking like septa in the liver) was seen in 52 patients (46%). Forty-seven of the 53 patients who had septal calcification on unenhanced CT scans had septal enhancement on scans obtained after the administration of contrast material. The enhancement was found at sites of septal calcification in 44 patients and at noncalcified sites in 18 (15 had enhancement at both calcified and noncalcified sites). Five of 60 patients who did not have septal calcification on unenhanced CT scans had septal enhancement at noncalcified sites on scans obtained after the administration of contrast material. Amorphous enhancement (i.e., poorly defined and irregularly shaped enhancement) was seen in six patients (5%). Capsular enhancement (i.e., curvilinear enhancement along the hepatic surface) was seen in 12 patients (11%). Histologic studies showed broad fibrous septa at sites of septal enhancement. CONCLUSION: CT findings in patients with schistosomiasis japonica involving the liver include septal, amorphous, and capsular contrast enhancement. Septal enhancement occurs in broad fibrous septa. CT evidence of septal enhancement may suggest the diagnosis of hepatic schistosomiasis japonica, especially when no calcification is seen on unenhanced CT scans.

Adult↗

PubMed1992

[MR imaging of amyotrophic lateral sclerosis].

Magnetic resonance imaging (MR imaging) provides a sensitive method for mapping the normal and pathological distribution of iron in the brain. High field strength MR imaging (1.5 T) was used to evaluate eight patients with amyotrophic lateral sclerosis (ALS) and 49 neurological normal control patients. All eight ALS patients showed decreased signal intensity in the motor cortex on T2-weighted images, while only one of the normal control patients showed this finding. The results suggested that the decreased signal intensity in the motor cortex in ALS was caused by the deposition of iron in this area.

Adult↗