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Biomedical subjects

Katsumi Hayakawa

Publications and source records attributed to Katsumi Hayakawa.

At least 19 recordsLinked to original sources
PubMed2006

Cine MR imaging of uterine peristalsis in patients with endometriosis.

Endometriosis is one of the most important causes of infertility; however the precise mechanism by which it affects female fertility is unclear. The objective of this study was to study the functional aspects of the uterus by evaluating uterine contractility in patients with endometrial cysts of the ovary. The study population was recruited from two institutes and consisted of 26 women (periovulatory (10), luteal (13), and menstrual phase (3); age range: 19-51 years) with untreated endometriosis; the control group consisted of 12 healthy women (age range: 22-41 years). Cine MR imaging obtained by a 1.5T magnet was visually evaluated at 12x faster than real speed, focusing on the presence of uterine peristalsis, the direction and frequency of peristalsis, and the presence of sustained uterine contractions. Uterine peristalsis was identifiable in 3/10, 3/13, and 3/3 of the endometriosis patients in each menstrual cycle, respectively, and in 11/12, 3/12, and 5/12 of their control subjects. Peristaltic detection rate and frequency were significantly less for the endometriosis group than for the controls in the periovulatory phase only (p<0.05). Sustained contractions were recognized in 19/36 control subjects and in 13/26 endometriosis patients, but the difference was not significant. Uterine peristalsis appears to be suppressed during the periovulatory phase in patients with endometriosis, which may have an adverse effect on sperm transport.

Adult↗
PubMed2006

Dynamic helical CT mammography of breast cancer.

PURPOSE: The purpose of this study was to determine whether dynamic helical computed tomography (CT)-mammography could assist in selecting the most appropriate surgical method in women with breast cancer. MATERIALS AND METHODS: Preoperative contrast-enhanced helical CT scanning of the breast was performed on 133 female patients with suspicion of breast cancer at the same time as clinical, mammographic, and/or ultrasonographic examinations. The patients were scanned in the prone position with a specially designed CT-compatible device. A helical scan was made with rapid intravenous bolus injection (3 ml/s) of 100 ml of iodine contrast material. Three-dimensional maximum intensity projection (MIP) images were reconstructed, and CT findings were correlated with surgical and histopathological findings. RESULTS: Histopathological analysis revealed 84 malignant lesions and seven benign lesions. The sensitivity, specificity, and accuracy levels of the CT scanning were 94.6%, 58.6%, and 78.9%. Helical scanning alone revealed additional contralateral carcinomas in three of four patients and additional ipsilateral carcinomas in three of five patients. However, the technique gave false-positive readings in 24 patients. The preoperative CT-mammogram altered the surgical method in six patients. CONCLUSION: Dynamic helical CT-mammography in the prone position may be one of the choices of adjunct imaging in patients with suspected breast cancer scheduled for surgery.

Adult↗
PubMed2006

Comparative study of vascular enhancement on post-contrast CT using three dosages of iodinated contrast media for the aim of detecting brain metastasis in patients with lung cancer.

OBJECTIVE: A prospective double-blind randomized study was performed to compare the contrast of vascular enhancement using three dosages of iodinated contrast media for a possible metastatic lesion in the brain. MATERIALS AND METHODS: Sixty-six patients with lung cancer received brain computed tomography (CT) with intravenous administration of iodinated contrast medium (CM). The patients were randomly assigned to receive one of the three types of CM: 30 g iodine, 24 g iodine, and 15 g iodine. Three radiologists judged the degree of vascular contrast enhancement and diagnosed the presence of brain metastasis. The CT numbers in major arteries were also measured. RESULTS: The subjective average scores with standard deviation were 2.06+/-0.48, 1.97+/-048, and 1.44+/-0.43, and the measured average CT numbers with standard deviation (SD) were 168.5+/-39.6, 166.1+/-28.6, and 146.1+/-27.0 HU with 30 g, 24 g, and 15 g iodine, respectively. The scores and the CT numbers in 15 g iodine were less than those with 30 g and 24 g iodine. Brain metastasis was detected in one patient each in groups A and C, and one false-positive case was found in group B. CONCLUSION: CT study with a dose of 24 g iodine showed equivalent quality on vascular enhancement in comparison with a 30 g iodine dose.

Adult↗
PubMed2005

Effects of oral 5-fluorouracil drugs on hepatic fat content in patients with colon cancer.

RATIONALE AND OBJECTIVES: The association between hepatic steatosis and oral 5-fluorouracil (5-FU) agents is clinically recognized but has not been systematically studied. The aim of this study was to determine the effects of 5-FU on hepatic fat content in patients undergoing oral 5-FU therapy and to compare the effects in three subgroups of 5-FU drugs. MATERIALS AND METHODS: Fifty-one patients with postoperative colon cancer (mean 61.1 years) were retrospectively studied. Forty-three patients were given adjuvant oral 5-FU therapy for a mean 3.3 years (5-FU group), and eight patients were not (control group). All patients underwent preoperative and postoperative abdominal computed tomography (CT) studies. The liver/spleen ratio was calculated from the CT attenuation values for the liver and spleen. We also compared the effects on hepatic appearance under CT of three 5-FU drugs: fluorouracil (n = 13), doxifluridine (n = 14), or UFT (a mixture of tegafur and uracil; n = 9). RESULTS: In the 5-FU group, the mean CT values for the liver were significantly reduced relative to values before therapy (P < .01) and to those of the control group (P < .0001). Fifteen of 43 patients (34.9%) developed steatosis. Of the three 5-FU drugs, fluorouracil and doxifluridine caused a significant decrease in hepatic CT values. CONCLUSION: 5-FU caused a significant decrease in CT attenuation, indicating an increase in hepatic fat content, and was associated with very frequent hepatic steatosis. UFT seemed less likely to cause hepatic fatty infiltration. CT examination was useful for early detection of drug-induced side effects on liver even before lab abnormality or clinical manifestation is observed.

Adult↗
PubMed2005

Uterine contractions evaluated on cine MR imaging in patients with uterine leiomyomas.

PURPOSE: Submucosal leiomyoma is one of the most recognized causes of infertility and habitual abortion. The purpose of this study is to evaluate uterine peristalsis, a cycle-related inherent contractility of uterus probably responsible for sperm transport and conservation of pregnancy, in patients with uterine leiomyomas using cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: Study population consisted of 26 female patients (age range: 19-51 years, mean: 41 years), in which 16 patients had submucosal leiomyomas and 10 patients had intramural or subserosal leiomyomas. We prospectively performed MR imaging of the midsagittal plane of uterus using 1.5 T magnet (Symphony, Siemens Medical Systems) with a body array coil, and obtained 60 half-Fourier acquisition single shot turbo spin echo (HASTE) images (Echo time=80 ms, FOV=300 mm, slice thickness 5 mm, matrix 256x256) within 2 min, and displayed them on cine mode at 12x faster than real speed. Evaluated were peristaltic movements at the endometral-myometrial junction and focal myometrial movements, adjacent to leiomyomas, regarding presence, direction, frequency, and conduction. RESULTS: The peristaltic movements were identified in 12/16 patients with submucosal lesions and 10/10 with other leiomyomas. The frequency and direction were cycle-related. Loss of peristalsis was noted adjacent to submucosal myomas in 4/12 patients, but was not in others. Focal myometrial movements were noted in 9/16 patients with submucosal myomas, but not in others. CONCLUSIONS: Uterine peristaltic movements were partly interrupted by submucosal leiomoymas, but not by myometrial or subserosal leiomyomas. Loss of peristalsis and focal myometrial movements was noted only adjacent to submucosal leiomyomas. These findings are considered to represent dysfunctional contractility, and may be related with pregnancy loss.

Adult↗
PubMed2005

Functional evaluation of the postoperative gastrointestinal tract using kinematic MR imaging: Quantitative assessment of peristaltic activity.

The purpose of this study is to demonstrate the feasibility of kinematic MR imaging in visualizing peristaltic activity in the reconstructed gastrointestinal tract with quantitative measurements. Sixteen patients with gastrointestinal reconstruction were studied with kinematic MR imaging using HASTE and/or true FISP. Peristaltic waves were noted in the retrosternal gastric segment after gastric pull through (frequency = 3.0 +/- 0.5 times/min, velocity = 2.6 +/- 0.6 mm/s) and in the residual antrum after cardiectomy (frequency = 3 times/min, velocity = 4.0 mm/s). Peristaltic waves were not apparent in the residual fundus after distal gastrectomy and in the reconstructed jejunum after pancreatoduodenectomy and gastrojejunostomy.

Aged↗
PubMed2005

Calcium binding by gadolinium-based MR contrast agents.

PURPOSE: This study was conducted to characterize the alterations in ionic sodium, potassium, and calcium by gadolinium-based MR contrast agents. MATERIALS AND METHODS: An electrolyte solution (ES) containing 1.2 mM/L calcium ions,120 mM/L sodium, and 4.0 mM/L potassium were diluted with various gadolinium compounds and alterations in ionized electrolytes were measured using an ion-specific electrometer. Gadolinium compounds including Gd-DTPA, Gd-DOTA, gadoteridol, gadodiamide, meglumine/sodium diatrizoate (76% Urografin), and isotonic saline as a control were investigated. The dilution ranged from 5% (ES/test solution = 100/5) to 100%. Alterations of ionic electrolytes were measured. Calcium-binding capacities caused by each gadolinium compound also were measured. RESULTS: The alterations of ionic sodium and potassium by gadolinium compound were similar to those of isotonic saline. A significant reduction in ionized calcium was observed with Gd-DTPA and Gd-DOTA in comparison with gadoteridol and gadodiamide. CONCLUSION: Ionic gadolinium compounds induced significant reductions of calcium ions in vitro compared with non-ionic gadolinium compounds.

Calcium↗
PubMed2004

MR imaging of ovarian hemorrhage.

BACKGROUND: To review MR appearances of ovarian hemorrhage, and to describe its characteristic imaging findings. METHODS: 12 women (age range, 20-44, mean, 26 years) with suspected ovarian hemorrhage underwent pelvic MR examinations. We retrospectively reviewed MR findings regarding signal intensities, localization, and wall enhancement of adnexal masses, and signal intensities of ascites. RESULTS: Adnexal masses were detected in all cases. In eight cases, adnexal mass exhibited intermediate signal intensity on T1WI, and intermediate to low signal intensity on T2WI. In other case, adnexal mass exhibited marked hyperintensity on T1WI. In the remaining three cases, cystic mass with low signal intensity on T1WI and high signal intensity on T2WI was noted. Ascites was present in all cases, and showed intermediate signal on T1WI and intermediate to low signal on T2WI. CONCLUSIONS: In ovarian hemorrhage, hemorrhagic ascites and adnexal mass was visualized with specific MR signal intensity. Due to its sensitivity for identifying blood, MR imaging is useful in the diagnosis of ovarian hemorrhage, especially when ultrasonography findings are not definitive.

Adnexal Diseases↗
PubMed2003

Accumulation of 99mTc-PMT in renal metastasis of hepatocellular carcinoma.

We describe here a case in which 99mTc-Sn-N-pyridoxy-5-methyltryptophan (99mTc-PMT) scintigraphy was useful in diagnosing renal metastasis of hepatocellular carcinoma (HCC). A 62-year-old man who had undergone hepatectomy for HCC presented 6 years after initial diagnosis with left flank pain and was found on CT and MRI to have a tumor in the left kidney. Hepatobiliary scintigraphy using 99Tc-PMT was performed, and 99mTc-PMT accumulation was found in the tumor. Nephrectomy was performed and metastasis of HCC was confirmed.

Carcinoma, Hepatocellular↗
PubMed2003

Effects of tamoxifen on hepatic fat content and the development of hepatic steatosis in patients with breast cancer: high frequency of involvement and rapid reversal after completion of tamoxifen therapy.

OBJECTIVE: A study was conducted on hepatic fat content to investigate the frequency and clinical course of hepatic steatosis induced by tamoxifen. MATERIALS AND METHODS: Sixty-seven patients with breast cancer treated with adjuvant tamoxifen were included. The patients underwent postoperative annual abdominal CT, both with and without contrast enhancement, for 5 years. We retrospectively reviewed unenhanced CT images and obtained hepatic and splenic CT attenuation values to calculate the liver-spleen ratio. Hepatic steatosis was defined as a liver-spleen ratio of less than 0:9, and its degree was classified as mild (liver-spleen ratio, 0:5-0:9), moderate (0-0:5), or severe (<0). The pattern of steatosis was classified as generalized, lobar, segmental, or focal. RESULTS: In the study population, hepatic CT values decreased during therapy (p < 0.0001, t test) and increased after therapy (p < 0.0001, paired t test). Twenty-nine patients (43.2%) developed hepatic steatosis within the first 2 years; its degree was mild in 16, moderate in nine, and severe in four. Seventeen patients showed a generalized pattern of steatosis, and the other 12 showed a lobar pattern. Twenty-three of these patients showed an increase in the liver-spleen ratio after therapy to within the normal range, with a mean recovery time of 1.2 years after therapy ended. None progressed to steatohepatitis or cirrhosis. CONCLUSION: Tamoxifen had a statistically significant influence on hepatic fat content and was associated with frequent development of hepatic steatosis. Radiologists should be aware of this phenomenon and the possible occurrence of hepatic dysfunction and should differentiate steatosis from metastasis in postoperative patients with breast cancer.

Adipose Tissue↗
PubMed2002

Unilateral cerebral polymicrogyria with ipsilateral cerebral hemiatrophy.

We evaluated six children in whom MR imaging showed unilateral cerebral polymicrogyria associated with ipsilateral cerebral atrophy and ipsilateral brain stem atrophy. The aim of this study was to clarify whether this disorder based on neuroimaging constitutes a new homogeneous clinical entity. The subjects were six children whose ages at the time of MR imaging ranged from 8 months to 11 years. Their clinical and MR features were analyzed. All of the children were born between 38 and 42 weeks gestation, without any significant perinatal events. Spastic hemiplegia and epilepsy were observed in all of the patients, and mental retardation was observed in four. The MR findings included unilateral cerebral polymicrogyria associated with ipsilateral cerebral hemiatrophy and ipsilateral brain stem atrophy in all patients. The ipsilateral sylvian fissure was hypoplastic in four patients. These patients showed relatively homogeneous clinical and neuroimaging features. Although the additional clinical features varied according to the site and the extent affected by the polymicrogyria, this disorder could constitute a new relatively homogeneous clinical entity.

Brain Diseases↗
PubMed2002

CT and MRI findings of cyclosporine-related encephalopathy and hypertensive encephalopathy.

We present the MRI and CT findings of one child with cyclosporine-related encephalopathy, and one child with hypertensive encephalopathy following cyclosporine-related encephalopathy. The imaging findings were shown well on T2-weighted and fluid-attenuated inversion recovery (FLAIR) MR images. Cyclosporine-related encephalopathy was distributed predominantly in the posterior white matter. Hypertensive encephalopathy showed similar changes of CT attenuation, but with wider distribution. These two disorders seem to have the same pathogenesis.

Brain↗
PubMed2002

Tumor thrombi in the portal vein system originating from gastrointestinal tract cancer.

Intraluminal tumor thrombus in the portal vein (PV) system originating from gastrointestinal (GI) tract cancer is a rare condition. There are two types of such thrombi, one arising indirectly from metastatic liver cancer and the other directly from the primary lesion. We report here three patients with the direct type and two with the indirect type; i.e., a total of five patients with gastric or large intestinal cancer with PV tumor thrombus. In all patients, the primary lesion was surgically resected; in two patients, the tumor thrombus was easily extirpated by direct opening of the PV. It is noteworthy that a patient whose tumor thrombus could not be treated died of cancer with liver failure, caused by expansive growth of the PV tumor thrombus, 4 months after the finding of the PV thrombus. Because PV tumor thrombus may, possibly, determine the patient's length of survival, in addition to causing cancer progression, surgical thrombectomy, combined with resection of the primary cancer and metastatic liver cancer, should be considered for prolongation of survival, if all macroscopic lesions can be controlled and if the tumor thrombus is a synchronous and recent one.

Adenocarcinoma↗
PubMedDate not supplied

MRI of early unruptured ectopic pregnancy: detection of gestational sac.

We report two cases of unruptured tubal pregnancy that were evaluated on MRI at 5 weeks' gestation. In both cases, MRI revealed gestational sac-like structures surrounded by thickened walls outside the ovaries. At the periphery of gestational sac-like structures, small amounts of fresh blood were also identified. These findings highly indicate ectopic pregnancy in a patient with elevated human chorionic gonadotropin level.

Adult↗
PubMedDate not supplied

Magnetic resonance imaging findings in gynecologic emergencies.

Gynecologic emergencies include a variety of gynecologic diseases that manifest with acute lower abdominal pain, fever, and vaginal bleeding. Recent technical advances enable the application of magnetic resonance (MR) imaging to these conditions, which may add clinically useful information in a short enough time for emergent diagnosis. In this study, the acute gynecologic conditions in which MR imaging studies were performed are reviewed, and the characteristic MR findings in gynecologic emergencies, including ovarian hemorrhage, ectopic pregnancy, tumor rupture, torsion, hemorrhage, infarction, and pelvic inflammatory diseases, are demonstrated. Familiarity of these findings aids accurate diagnosis and proper treatment choices in gynecologic emergencies.

Abdominal Pain↗
PubMedDate not supplied

Multiple enhancing lesions detected on dynamic helical computed tomography-mammography.

OBJECTIVES: To review pathologic diagnoses of multiple enhancing lesions in a unilateral breast detected on dynamic helical computed tomography (CT)-mammography and to correlate imaging findings with pathologic results. METHODS: From May 1998 to July 2001, preoperative contrast-enhanced helical CT scanning of the breast was performed in 200 female patients clinically diagnosed with breast cancer. The patients were scanned in the prone position in a specially designed CT-compatible device, with rapid intravenous bolus injection of 100 mL contrast material. Three-dimensional maximum intensity projection images were reconstructed. The cases with multiple enhancing lesions in a unilateral breast were retrospectively reviewed. The maximum diameter of the largest stain in each breast was measured, the patterns of multiple enhancing lesions were classified, and imaging findings were correlated with surgical and pathologic outcomes. RESULTS: Twenty-five of 200 (12.5%) patients (age range: 39-86 years, mean age: 56 years) showed multiple stains on CT-mammography. Two patients showed multiple stains in bilateral breasts. The maximum diameter of the largest stain in each breast ranged from 5 to 55 mm (average: 22 mm). Among cases with multiple stains, 21 (78%) were shown to be invasive ductal carcinoma with multiple satellite cancer nodules. Four cases were ductal carcinoma in situ with multiple satellite nodules. One case revealed multiple fibroadenomas, and another showed intraductal papilloma. CONCLUSIONS: Multiple enhancing lesions on CT-mammography in patients with breast cancer were relatively common, and most of them represented multiple cancer lesions. Dynamic CT-mammography is potentially useful in evaluating the spread of breast cancer.

Adult↗
PubMedDate not supplied

Benign or malignant?: differentiating breast lesions with computed tomography attenuation values on dynamic computed tomography mammography.

OBJECTIVE: To evaluate enhancement effects of breast lesions with dynamic computed tomography (CT) and to determine characteristics to aid in differential diagnosis of benign and malignant lesions. METHODS: One hundred seventy-six women underwent preoperative dynamic CT, in which they were scanned with rapid injection of contrast media (3 mL/s) after 30 seconds and 2 minutes (early and delayed phases, respectively). The CT values and enhancement patterns of malignant lesions (n = 154) were compared with those of benign lesions (n = 22), and the cut point of CT values with the best validity was analyzed. RESULTS: The CT values of malignant lesions were higher than those of benign lesions in both phases (P < 0.0001). The cut point was determined to be 60 Hounsfield units (HU) in the early phase (44% validity, 90% sensitivity). Washout and plateau patterns were more commonly seen in the malignant group (73% specificity). CONCLUSIONS: The analysis of enhancement effects on CT may lead to more appropriate differentiation of benign and malignant lesions.

Adult↗