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Biomedical subjects

H Okizuka

Publications and source records attributed to H Okizuka.

At least 19 recordsLinked to original sources
PubMed2002

Primary Sjögren's syndrome initially manifested by optic neuritis: MRI findings.

We herein describe the MRI findings in a patient clinically diagnosed with primary Sjögren's syndrome (SjS) initially manifested by retrobulbar optic neuritis. A 63-year-old woman suddenly had left ocular pain and progressive visual disturbance. MR T2-weighted images revealed hyperintensity in the left optic nerve, with swelling. Contrast-enhanced T1-weighted images showed no abnormal enhancement. Follow-up MRI 6 months after admission revealed no significant changes in the affected optic nerve. To our knowledge, optic neuritis as a complication of SjS has been reported in ten patients [1, 2, 3, 4, 5, 6] and MRI findings in only one of them [6]. We thought MR images were useful for visualizing optic nerve involvement in SjS and observing its course.

Female↗
PubMed2001

Gastrointestinal stromal tumor of the rectum.

Gastrointestinal stromal tumors (GISTs) are characterized by remarkable variability in their differentiation potential, but most of these lesions do not display convincing smooth muscle or neuronal differentiation. The GISTs arising from the rectum or anal canal are extremely uncommon. We present a case of immunohistochemically proven GIST of the rectum, which was characterized by homogenous isointensity mass without necrosis or hemorrhage on T2-weighted image and by enhancement on gadolinium-enhanced study.

Carcinoma↗
PubMed1995

Scintigraphic detection of recurrence of medullary thyroid cancer.

A case of recurrent medullary thyroid cancer (MTC) was evaluated with 123I-MIBG, 99mTc(V)-dimercaptosuccinic acid (DMSA), and 201Tl scintigraphy. This patient had been operated on for MTC in the right thyroid. Recently a left neck mass was noticed, and was suspected of being a recurrence of MTC based on increased plasma calcitonin (CT) and carcinoembryonic antigen (CEA). He was operated on for the neck mass which revealed MTC, and papillary thyroid cancer was incidentally found in the left thyroid, but the CT and CEA levels remained high, and remaining MTC tumor was suspected. But the location of the tumor was unknown. Although 99mTc(V)-DMSA scintigraphy is generally believed to be superior in sensitivity to 123I-MIBG scintigraphy, it did not demonstrate the tumor site but 201Tl and 123I-MIBG did. Furthermore, 123I-MIBG scintigraphy has greater specificity for tumors which arise in the neural crest. Judging from the results of this case and cases reported in the literatures, both 123I-MIBG and 99mTc(V)-DMSA should be performed in the detection of recurrent MTC.

3-Iodobenzylguanidine↗
PubMed1994

T1-weighted images with ECG gating using partial flip angle spin-echo imaging.

ECG-gated spin-echo imaging can reduce vascular artefacts compared with spin-echo scans without gating. However, this method produces poor T1-weighted images because the repetition time (TR) is limited by the heart rate. We investigated the value of low flip angle spin-echo imaging for increasing T1-dependent contrast when using ECG gating. Using computer simulation, the predicted contrast increased with decreasing the flip angle, and the effect was almost saturated at a flip angle of around 40 degrees. With the application of this flip angle, the identical image contrast as a T1-weighted image (TR = 400 ms) can be obtained within the heart rate range of 65 to 75 beats/min. For clinical evaluation, the tissue contrast index values ((signal intensity in the lesion-signal intensity in the muscle)2 x 100/signal intensity in the muscle) obtained by conventional spin-echo and low flip angle spin-echo imaging were compared in 17 patients. The contrast index of low flip angle spin-echo images (74.0 +/- 52.0) was significantly higher than that of conventional spin-echo images (40.9 +/- 35.9). Thus, ECG-gated low flip angle spin-echo imaging provided better T1-dependent contrast than conventional ECG-gated spin-echo imaging. This method may be especially useful for Gd-DTPA-enhanced magnetic resonance imaging.

Aged↗
PubMed1994

Prediction of effectiveness of intraperitoneal chemotherapy by intraperitoneal scintigraphy in patients with advanced ovarian carcinoma.

Intraperitoneal scintigraphy with Tc-99m MAA was performed in nine patients with carcinomatous peritonitis secondary to ovarian or tubal carcinoma. Tc-99m MAA (370 MBq) and NaCl was delivered through an implantable injection port. For patients with good diffusion on intraperitoneal scintigraphy, intraperitoneal chemotherapy was effective. However, for patients with only local diffusion, intraperitoneal chemotherapy was not effective. Intraperitoneal scintigraphy can predict the effectiveness Intraperitoneal scintigraphy can predict the effectiveness of chemotherapy through the implantable injection port.

Adult↗
PubMed1994

Benign prostatic hyperplasia: value of MR imaging for determining histologic type.

PURPOSE: To assess the value of magnetic resonance (MR) imaging for determining the histologic type of benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: Unenhanced T1- and T2-weighted images and gadolinium-enhanced T1-weighted images were obtained in the transverse plane at 1.5 T in 33 patients with BPH. Hyperphasia was classified as stromal or nonstromal. Nonstromal hyperplasia was diagnosed if (a) the nodules in the inner gland had heterogeneous high signal intensity on T2-weighted images and peripheral enhancement on gadolinium-enhanced images, (b) a surgical capsule was present, or (c) the inner gland volume to total volume ratio was greater than 0.75. RESULTS: A correct diagnosis was made with MR imaging in 23 of 24 patients with nonstromal hyperplasia and eight of nine with stromal hyperplasia (94% accuracy). In nonstromal hyperplasia, nodular lesions were seen in 20 patients and a surgical capsule was seen in 19. Eighteen patients had a transition zone ratio greater than 0.75. CONCLUSION: MR imaging appears to be useful for choosing the type of pharmacotherapy performed because accurate histologic assessment is possible.

Aged↗
PubMed1993

[Staging of rectal cancer: assessment with Gd-DTPA enhanced MR imaging].

This study was designed to assess the value of Gd-DTPA enhanced imaging in the staging of rectal carcinoma. Twenty-five patients were prospectively evaluated with MR imaging using a 1.5 Tesla unit. Based on the results of a barium study and/or digital examination, a balloon catheter was inserted to the level of the lesion before examination. Both T1- and T2-weighted images and Gd-DTPA enhanced images were obtained in all patients, and Gd-DTPA enhanced fat-saturation images were obtained in 11 patients. When both T1- and T2-weighted images were used, 24% of tumors were ill defined. However, when Gd-DTPA and Gd-DTPA enhanced fat-saturation imaging was added, all tumors were well defined and the quality of the images increased. There was no significant difference between images in the detection of muscular invasion. In the detection of perirectal fat invasion, however Gd-DTPA fat-saturation imaging showed increased sensitivity. Nevertheless, it also decreased specificity, so there was no significant difference between images. In the detection of metastatic lymph nodes, Gd-DTPA enhanced and Gd-DTPA enhanced fat-saturation imaging were not useful. Tumor detection using Gd-DTPA enhanced fat-saturation images was excellent. However, the accuracy of staging was not improved by supplemental Gd-DTPA enhancement.

Adult↗
PubMed1993

Pelvic endometriosis: detection and diagnosis with chemical shift MR imaging.

Fat-saturation magnetic resonance (MR) imaging for detection and characterization of pelvic endometriosis was prospectively investigated in 35 women with a clinical diagnosis of the disease. Large endometrioma was diagnosed when the lesion was larger than 1 cm in diameter and hyperintense on T1- and T2-weighted images. Small endometrioma was diagnosed when a well-demarcated hyperintense lesion less than 1 cm in diameter was seen on T1-weighted or fat-saturated T1-weighted images. Surgery performed after MR imaging revealed a normal pelvis in six patients, endometriosis in 26 (33 large and 19 small endometriomas), and other cystic lesions in three. Conventional T1- and T2-weighted imaging accurately demonstrated 27 of 33 large endometriomas and two of 19 small endometriomas. Fat-saturation T1-weighted imaging in combination with conventional technique accurately demonstrated 30 of 33 large and nine of 19 small endometriomas. Diagnostic accuracy was improved with addition of fat-saturated images, so their use together with conventional images is recommended in assessment of endometriosis.

Adipose Tissue↗
PubMed1993

Ovarian cystic teratomas: value of chemical fat saturation magnetic resonance imaging.

Chemical fat saturation (FS) magnetic resonance imaging (MRI) for the characterization of ovarian cystic teratoma was evaluated in 19 patients with 22 lesions. The tumour was evaluated for signal intensity, location and size; the presence of chemical shift artefact, debris and fat-fluid level. Ovarian cystic teratoma was diagnosed prospectively if the mass contained fat and/or more than one type of internal pattern on (1) SE T1-, T2-, (2) SE T1-, T2-, FS T1-weighted images. A correct diagnosis was reached in 17 of 22 tumours on conventional T1- and T2-weighted images, and in 21 of 22 tumours when fat-saturation images were added. When fat-saturation images were added, four of five tumours misdiagnosed on conventional images were then correctly diagnosed. These tumours contained only small amounts of fat. Fat-saturation images could detect smaller amounts of fat than conventional images. However, one tumour did not show decreased intensity on fat saturation images, and was not diagnosed even when fat-saturation images were added. Fat saturation images have been shown to be of value in diagnosing cystic teratomas.

Adolescent↗
PubMed1992

The value of magnetic resonance relaxation time in staging ovarian endometrial cysts.

We evaluated the use of magnetic resonance imaging (MRI) in the pre-operative staging of 15 endometrial cysts. The effect of the iron content on the T1 and T2 relaxation times was assessed in confirmed endometrial cysts employing a 0.15 T MR system and a 200 MHz spectrometer. There was a positive linear correlation (r = 0.93) between the T1 values of the lesions obtained using the MR system (T1) and those of the resected cyst contents obtained using the spectrometer (sp-T1). A similar relationship was found between T2 and sp-T2 (r = 0.87). There was a negative linear relationship between the T1 value and the cyst iron content (r = -0.81), but there was no relationship between the T2 value and the iron content. T1 was 412 +/- 91 ms for Stage II cysts (n = 3), 356 +/- 126 ms for Stage III cysts (n = 3) and 208 +/- 30 ms for Stage IV cysts (n = 9). The T1 value for Stage IV cysts was significantly shorter than that for Stages II and III cysts (p less than 0.05). Thus, the T1 value was useful in distinguishing fresh from old endometrial cysts, suggesting that the MRI T1 relaxation time might be useful for staging ovarian endometrial cysts before surgery.

Endometriosis↗
PubMed1991

[Normal female urethra and paraurethral structure--evaluation with MR imaging].

The appearance of the normal female urethra on magnetic resonance (MR) images was studied in 40 patients by means of a 1.5 Tesla unit. Morphologic characteristics and anatomic details of the urethra and pubourethral ligament were demonstrated in each patient. MR imaging depicted an outer muscle layer of low signal intensity. Medial to the outer muscle layer, the submucosa was seen as a high-signal-intensity ring, followed by an inner low-signal-intensity ring. In the mid-urethra, a central high-signal-intensity spot was seen in 38% of cases, a finding that may be related to urine and mucus within the mucosal cells. The zonal anatomy of the female urethra was obscure in the over 60 years of age. MR imaging is an excellent tool for demonstrating female urethral anatomy.

Adolescent↗
PubMed1991

[Bone infarction and fat island appearing as local defects in radionuclide bone marrow imaging].

Parallel studies of radionuclide bone marrow imaging and bone scanning are helpful in the early diagnosis of skeletal metastasis. In bone marrow imaging, most lesions are observed as a local defect. We had two cases of nonmetastatic lesions which appeared as local defects in bone marrow imaging. The first case was a male Hodgkin's disease patient, aged 48, who had been treated with frequent chemotherapy, including the administration of a large quantities of steroids. He complained of slight pain in the left shoulder. Without increased uptake in bone scanning, abnormal accumulation of 67Ga-citrate and a local defect in bone marrow imaging appeared, corresponding to localization of the pain. Suspecting bone marrow metastasis, we performed magnetic resonance imaging (MRI). An area of slightly decreased intensity in T1-weighted spin-echo images and lower intensity than fat tissue in T2-weighted images were observed, although it was slightly enhanced by Gd-DTPA. This lesion was diagnosed by biopsy as a bone infarction. The second case was that of a 69-year-old male lung cancer patient. Though no abnormality was revealed by bone scanning or 67Ga-citrate scintigraphy, an apparent defect at the 10th thoracic vertebra was observed in bone marrow imaging. It was not accompanied by pain. MRI was also performed in this case. This was depicted as a clearly defined high intensity area. This was diagnosed as a fat island, and no change has been seen in the seven months of follow up. In conclusion, it is necessary to consider the possibility of nonmetastatic lesions, when local defects appear in bone marrow imaging performed on cancer patients.

Adipose Tissue↗
PubMed1990

[Post radiation changes in the rectum: assessment by MR imaging].

MRI findings of pelvic radiation changes in 42 patients were correlated with the tumor and critical tissue dose, time post treatment, and clinical symptoms. The severity of tissue changes was graded. The ability of MRI to differentiate post radiation tissue changes from residual or recurrent tumor was also correlated. Radiation tissue toxicity increased significantly when the dose exceeded 4,500 cGy, with the incidence of marked rectal changes rising from 8% to 44% with a dose greater than 4,500 cGy. All grades of tissue change were seen in the rectum of time from start of therapy. All patients who exhibited clinical grade 2 or 3 rectal changes showed moderate or severe changes on MRI. Grade 1 MRI changes indicative of mucosal edema were present in 33% of patients with no clinical symptoms. In conclusion, the gradation and sequence of MRI changes following radiation therapy to the pelvis have been documented and correlated with clinical findings. With its potential for distinguishing radiation change from recurrent tumor. MRI should prove to be of value in the assessment of the post-radiation pelvis.

Adult↗