Hiromi Okizuka

MR detection of degenerating uterine leiomyomas

Objective Gonadotropin-releasing hormone (GnRH) analogues have been advocated for the conservative management of uterine leiomyoma. These drugs induce a hypoestrogenic state and affect undegenerated myoma cells. Therefore, we evaluated the usefulness of MRI for distinguishing undegenerated and degenerated leiomyomas. Materials and Methods Twenty lesions were studied in 16 patients with surgically resected leiomyoma. A 1.5 T unit was used to obtain T1− and T2-weighted images and Gd-DTPA-enhanced T1-weighted images. Signal intensity maps were made for each pulse sequence, and detailed histological maps were also made in the same plane as the MR images. Then the MR maps were compared with the histological maps of the resected specimens. Results Interstitial edema, the initial sign of degeneration, was detected as a high signal intensity region on T2-weighted images and showed enhancement with Gd-DTPA. Hyaline degeneration could not be distinguished from smooth muscle whorls on T1− and T2-weighted images. However, undegenerated leiomyoma could be distinguished from hyaline degeneration, because the former was slightly enhanced by Gd-DTPA but the latter was not. Conclusion These findings showed that Gd-DTPA-enhanced MRI can distinguish undegenerated leiomyomas from degenerated leiomyomas and suggest that MRI may be useful for predicting the response of this tumor to GnRH analogue therapy.

Gastrointestinal stromal tumor of the rectum

Abstract 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.

Accuracy of whole-body FDG-PET/CT for detecting brain metastases from non-central nervous system tumors

ObjectivePositron emission tomography (PET) using 18F-fluoro-2-deoxy-d-glucose (FDG) has a limitation in detecting cerebral metastases; however, the feasibility of detection by inline PET/computed tomography (CT) system remains unknown. We evaluated the accuracy of FDG-PET/CT of body imaging protocol for the detection of cerebral metastases when compared with PET alone and CT alone.MethodsFifty patients underwent whole-body FDG-PET/CT scanning including the brain and contrastenhanced brain MR (magnetic resonance) scan. PET-only, CT-only, and the fused images were interpreted, and the confidence of presence of cerebral metastases was recorded using a five-point grading scale. Area under the receiver-operating characteristic (ROC) curve (Az) was calculated. Differences among the three modalities were tested with the Cochran-Q test, followed by multiple comparisons using the McNemar test with Bonferroni adjustment.ResultsMagnetic resonance imaging revealed 70 cerebral metastatic lesions in 20 patients. Patient-based analysis showed that the sensitivity, specificity, accuracy, and Az of PET-alone interpretation were 45%, 80%, 66%, and 0.6025, respectively, those of CT-alone interpretation were 50%, 97%, 78%, and 0.7158, respectively, and those of fused-image interpretation were 50%, 93%, 76%, and 0.7242, respectively. ROC analysis revealed significant differences among the three interpretation methods (P = 0.0238) and between PET and PET/CT (P = 0.0129). The sensitivity of PET, CT, and fused-image interpretation for detecting 70 lesions was 13%, 20%, and 20%, respectively.ConclusionsEven with an integrated PET/CT scanner of body imaging protocol, the sensitivity of cerebral metastases remained unsatisfactory. To assess intracranial lesions, MR scanning should still be considered.

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.

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.

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

Abstract. We herein describe the MRI findings in a patient clinically diagnosed with primary Sjögrens 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.

MRI in predicting the response of ovarian endometriomas to hormone therapy

OBJECTIVE Our goal was to investigate the usefulness of MRI in predicting the response of endometriomas to hormone therapy. MATERIALS AND METHODS MRI and laparoscopy at the onset of treatment and follow-up MRI after 6 months of hormone therapy were performed in 21 patients with 49 endometriomas. T1- and T2-weighted images were obtained with a 1.5 T apparatus using a body coil. The lesions were divided into a responder group and a nonresponder group according to whether the lesion size decreased by > or = 50% or not. RESULTS With MRI, shading was seen in 25 of 27 lesions (93%) from the nonresponder group, but in only 6 of 22 (27%) from the responder group. Low SI rim was seen in 59% of the responders and 89% of the nonresponders. Multiplicity in 68% of the responders and in 85% of the nonresponders and irregularity in 41% of the responders and in 78% of the nonresponders were shown. Multiple logistic analysis revealed shading was the most important factor in prediction of the response to hormone therapy. CONCLUSION Shading was an important sign in evaluating the response of endometriomas to hormone therapy. MRI may assist in selecting the appropriate therapy for endometriomas.

CT assessment of postirradiation changes in the rectum and perirectal region.

Postirradiation changes in the rectum and perirectal tissue were assessed by computed tomography (CT) in 55 patients (total of 60 examinations) and correlated with radiation dose and time elapsed. Thickening of the perirectal fascia, increased density of the perirectal fat, and swelling of the rectal wall occurred in 48, 60, and 8% of patients, respectively, regardless of radiation dose within 30 Gy. However, widening of the presacral space was seen in 8% of patients receiving a rectal dose of less than 45 Gy, a percentage that increased to 16% for patients receiving 45 Gy or more. Thickening of the perirectal fascia, increased density of the perirectal fat, widening of the presacral space, and muscular changes were seen regardless of the time from the start of therapy. CT does not appear to be reliable enough in detecting residual or recurrent tumor in the rectum. However, knowledge of the CT features of postirradiation changes is helpful for diagnosis in patients with pelvic malignancies.

Postsurgical pelvis: treatment follow-up.

Imaging for recurrence and complications of gynecologic malignancies following treatment with radical hysterectomy, chemotherapy, and radiation therapy has become an important determinant for treatment options available to patients. MR imaging and computed tomography can be used to provide evidence of limited local disease recurrence and thereby identify disease that is still potentially curable with adjuvant treatments. This article examines the imaging modalities currently used to detect recurrence and assist in making treatment changes for gynecologic malignancies and presents specific patient findings following definitive primary treatment of uterine cancer and ovarian cancer with radical hysterectomy, radiation therapy, or chemotherapy.

Colorectal carcinoma : evaluation with ultrafast CT

We investigated the value of ultrafast computed tomography for the preoperative assessment of colorectal carcinoma. Ultrafast CT demonstrated the primary tumor in 25 (89%) of 28 patients. Local tumor extension was detected with a sensitivity of 90%, a specificity of 78%, and an overall accuracy of 82%. Invasion into adjacent organs was detected with a sensitivity of 80%, a specificity of 91%, and an overall accuracy of 89%. Diagnoses of pericolic or perirectal lymph node metastasis were true-positive in ten, true-negative in 12, false-positive in one, and false-negative in two and those for distant lymph node metastasis were true-positive in four, true-negative in 24, and false-negative in one. Ultrafast CT may be more useful than conventional CT in evaluating local extension and pericolic or perirectal lymph node metastases because it avoids motion artifact.