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Biomedical subjects

Yuji Itai

Publications and source records attributed to Yuji Itai.

At least 19 recordsLinked to original sources
PubMed2003

High-resolution MR imaging of triangular fibrocartilage complex (TFCC): comparison of microscopy coils and a conventional small surface coil.

OBJECTIVE: To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively. DESIGN AND PATIENTS: Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 mm in diameter), a 47-mm microscopy surface coil and a 23-mm microscopy surface coil) at 1.5 T. Qualitative image analysis of MR images with three coils was performed by two radiologists who assigned one of five numerical scores (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) for five TFCC components, which were disc proper, triangular ligament, meniscus homologue, ulnotriquetral and ulnolunate ligament. Quantitative analysis included the signal-to-noise ratio (S/N) of the disc proper of TFCC, the lunate cartilage, the lunate bone and the contrast-noise-ratio (C/N) between articular cartilage and disc proper or bone marrow were measured. RESULTS: All structures show higher scores qualitatively on MR with microscopy coils than those with a C4 coil, and the difference was significant with the exception of the ulnolunate ligament. MR with microscopy coils showed significantly higher S/N values than those with a conventional surface coil (P<0.05 to P<0.001). T2*-weighted images using microscopy coils showed significantly higher cartilage-disc proper C/N and cartilage-bone marrow C/N (P<0.01 to P<0.001). On proton density-weighted images, the C/N between cartilage and disc proper with two microscopy coils was significantly higher (P<0.01) than that with a conventional coil. CONCLUSION: High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions.

Adult↗
PubMed2003

Enhanced washout of 99mTc-tetrofosmin in hypertrophic cardiomyopathy: quantitative comparisons with regional 123I-BMIPP uptake and wall thickness determined by MRI.

The diagnostic value of technetium-99m tetrofosmin (TF) washout in hypertrophic cardiomyopathy (HCM) was examined by investigating its relation to the metabolic abnormality depicted by iodine-123 beta-methyl- p-iodophenylpentadecanoic acid (BMIPP) uptake and the left ventricular (LV) myocardial wall thickness as measured by magnetic resonance imaging (MRI). TF washout was evaluated in 31 patients with HCM and 23 normal control subjects using 30-min (early) and 3-h (delayed) TF single-photon emission tomography images. The LV myocardial wall was divided into 19 segments and the percentage TF washout, regional BMIPP uptake and LV wall thickness were measured in each segment. Mean TF washout in the patients with HCM was significantly faster than that in normal control subjects (23.7+/-5.7 vs 13.4+/-4.1, P<0.0001). In the patients with HCM, TF washout showed an excellent correlation with MRI wall thickness ( r=0.82, P<0.0001) and a good inverse correlation with regional BMIPP uptake ( r=-0.72, P<0.0001). In addition, a good linear correlation was observed between TF uptake and MRI wall thickness in the 19 regional segments. In conclusion, the degree of TF washout corresponds well with the severity of myocardial wall thickness and the degree of metabolic abnormality in patients with HCM. These results suggest that enhanced TF washout might provide additional clinical information regarding metabolic alterations in HCM.

Adult↗
PubMed2003

Aneurysm of the superficial femoral artery in an infant.

An isolated arterial aneurysm in childhood is extremely rare. We report a 1-year-old girl with an aneurysm of the right superficial femoral artery, presenting as an asymptomatic mass of the thigh. The aneurysm involved the whole superficial femoral artery (9 cm in length), and surgical treatment would have required replacement of the affected artery. Conservative treatment was chosen, influenced by the patient's rapid growth at that time. Non-invasive, 3-D contrast-enhanced magnetic resonance angiography (MRA) was useful as an alternative to conventional angiography for detailed evaluation of the femoral arteries, including the aneurysm.

Aneurysm↗
PubMed2003

Nonoperative assessment of nodal status for locally advanced cervical squamous cell carcinoma treated by radiotherapy with regard to patterns of treatment failure.

PURPOSE: Lymph node metastasis is a major prognostic factor in the treatment of cervical cancer, but its nonsurgical assessment is not necessarily accurate, particularly in small nodes. We evaluated whether node-negative status could be accurately assessed using a low cutoff measure. METHODS AND MATERIALS: The subjects were 84 patients with Stage IIB-IVA cervical squamous cell carcinoma treated by definitive radiotherapy. Nodal status was assessed by CT as negative (<5 mm), possibly positive (5-10 mm), or probably positive (>10 mm). Cause-specific survival and the disease-free rate, including the pelvic recurrence-free and distant metastasis-free rates, were estimated. RESULTS: The cause-specific survival, disease-free rate, and pelvic recurrence-free rate at 5 years were significantly higher for the 32 patients with node-negative disease (83.5%, 86.1%, and 86.1%) and the 17 patients with possibly node-positive disease (59.2%, 93.8%, and 93.8%) than for the 35 patients with probably node-positive disease (32.6%, 22.0%, and 46.8%), respectively. No significant difference was found between negative and possibly node-positive status. In contrast, the distant metastasis-free rate differed significantly among node-negative (96.4%), possibly node-positive (59.3%), and probably node-positive (35.1%) status. CONCLUSION: Node-negative status assessed using a strict cutoff measure may be useful as a strong predictor of cervical cancer being confined to the pelvis.

Adult↗
PubMed2003

A thickened or indistinct junctional zone on T2-weighted MR images in patients with endometrial carcinoma: pathologic consideration based on microcirculation.

Thickened or indistinct junctional zone (JZ) is a problematic finding in staging endometrial carcinoma. We studied the incidence, pathological cause of this condition correlated to microcirculation, and the utility of dynamic contrast MRI for differential diagnosis. T2-weighted images were analyzed in 119 cases with endometrial carcinoma. The enhancement of the JZ during the dynamic contrast MRI, histopathological causes, and the density of arterioles in the JZ were retrospectively analyzed in cases with thickened or indistinct JZ. The MRI histopathological correlation of all 31 patients with a thickened or indistinct JZ were analyzed, in which it was corresponded to myometrial cancer invasion only in 22%. The sensitivity of a poor early enhancement pattern on dynamic study for detecting myometrial invasion was 71.4%, the specificity was 100%, and the overall accuracy was 92.5%. Although only weak relationship between the contrast enhancement and the arteriole density was revealed, the arteriole density within the JZ with cancer invasion was significantly decreased. Poor enhancement of JZ in early dynamic phase was correlated with the decreased density of arterioles within the myometrium which was invaded by endometrial carcinoma. Dynamic contrast study should be performed in staging endometrial carcinoma especially when JZ was thickened or indistinct.

Endometrial Neoplasms↗
PubMed2003

The use of magnetic resonance imaging to evaluate the effects of cooling on skeletal muscle after strenuous exercise.

The purpose of this study was to investigate the separate effects of cooling during the acute (within 60 min post-exercise) or subacute (24-168 h post-exercise) phase on skeletal muscle after exercise. Twenty-eight male subjects [mean (SD) 23.8 (1.8) years] were randomly assigned to the control (COTG, n=10), cold-water immersion (CWIG, n=9), and double-cold-water immersion groups (DCWIG, n=9). The cold-water immersion (15 min) was administered to the subjects' legs after calf-raise exercise (CWIG: after recording initial post-exercise measures, DCWIG: after recording initial and 24 h post-exercise measures). Magnetic resonance T2-weighted images were obtained to calculate the T2 relaxation time (T2) of the triceps surae muscle before, immediately after, and at the following times post-exercise: 20, 40, and 60 min, and 24, 48, 96 and 168 h. In addition, the ankle joint range of motion, serum creatine kinase and lactate dehydrogenase, and muscle soreness level were investigated before and after exercise. In all groups, significant T2 elevations in the gastrocnemius muscle appeared from immediately after to 60 min after exercise (P<0.05). Thereafter, COTG showed significantly re-elevated T2 levels in the gastrocnemius at 96-168 h post-exercise (P<0.05), while CWIG and DCWIG showed significantly smaller T2 values than the COTG at 96 h post-exercise (P<0.05). In addition, COTG showed larger increases in serum enzymes at 96 h post-exercise (not significant) and significantly greater muscle soreness levels at 48 h post-exercise (P<0.05) than the cooling groups. The results of this study may suggest that cooling has no dramatic effect, but some minor effects on reducing exercise-induced muscle edema in the subacute phase and relieving the extent of the damaged muscle cells.

Adult↗
PubMed2003

Accelerated dynamic MR imaging with a parallel imaging technique for hypervascular hepatocellular carcinomas: usefulness of a test bolus in examination and subtraction imaging.

PURPOSE: To assess the impact of the accelerated dynamic MR imaging (ADMRI) approach using parallel imaging for detecting hypervascular hepatocellular carcinomas (HCCs) and to evaluate the usefulness of a test bolus in examination and subtraction imaging in this setting. MATERIALS AND METHODS: Thirty patients with 135 HCCs underwent ADMRI using a two-dimensional gradient-recalled echo sequence with parallel imaging. Seventeen patients were evaluated without a test bolus and 13 patients with a test bolus. The detectability of HCCs was calculated between the groups with and without a test bolus. ADMRI was evaluated regarding the signal-to-noise ratio (SNR) of the lesion and the liver, the contrast-to-noise ratio (CNR) of the lesion vs. the liver, and the feasibility of subtraction images. RESULTS: ADMRI with and without a test bolus had almost equal sensitivity (92.5% and 92.6%). No significant difference was seen in the SNR of lesions and the CNR of lesions vs. livers between both groups. With a test bolus, ADMRI could depict the peak enhancement of nodules on the 2nd or 3rd dynamic phases and optimized the timing of peak lesion enhancement. Subtraction images could be obtained regarding minimal slice misregistration. CONCLUSION: ADMRI had high detectability of HCCs with and without a test bolus.

Adult↗
PubMed2003

Fat suppression strategies in enhanced MR imaging of the breast: comparison of SPIR and water excitation sequences.

PURPOSE: To compare two fat suppression techniques of spectrally-selective inversion pulse (spectral presaturation with inversion recovery-SPIR) and spectral-spatial excitation pulse of water excitation (WE) for contrast-enhanced MR imaging of the breast. MATERIALS AND METHODS: Forty women with histologically-proven breast cancer were examined. Both pulse types were applied to postcontrast, axial, three-dimensional field echo sequence. Contrast noise ratios (CNR) of lesion-to-breast parenchyma, lesion-to-fat, and parenchyma-to-fat were determined. Qualitative image analysis using a four-point scale was also performed by two observers. RESULTS: All the CNR values of obtained with WE techniques were significantly higher than those with SPIR. Qualitative analysis indicated that the WE images were statistically superior for the lesion-to-breast parenchyma contrast while being slightly inferior to the SPIR images for fat suppression homogeneity without statistical significance. CONCLUSION: Compared to SPIR, the WE technique suppressed the subcutaneous fat signal more potently and improved the contrast of the enhanced breast lesion against the parenchyma and the subcutaneous fat. WE will be a powerful fat suppression strategy for enhanced MR imaging of the breast.

Adipose Tissue↗
PubMed2003

Evaluations of cooling exercised muscle with MR imaging and 31P MR spectroscopy.

PURPOSE: To investigate the effects of cooling human skeletal muscle after strenuous exercise using 31P MR spectroscopy and MR imaging. METHODS: 14 male subjects (mean age +/- SD, 23.8 +/- 2.3 yr) were randomly assigned to the normal (N = 7) or the cooling group (N = 7). All subjects performed the ankle plantar flexion exercise (12 repetitions, 5 sets). Localized 31P-spectra were collected from the medial gastrocnemius before and after exercise (immediately, 30, 60 min, 24, 48, 96, and 168 h) to determine the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular pH. Transaxial T2-weighted MR images of the medial gastrocnemius were obtained to calculate T2 relaxation time (T2), indicative of intramuscular water level, before and after exercise (24, 48, 96, and 168 h). In addition, the muscle soreness level was assessed at the same time as 31P-spectra measurements. Fifteen-minute cold-water immersion was administered to the cooling group after exercise and initial postexercise measurements. RESULTS: The control group showed significantly increased T2 from rest at 48 h after exercise (P < 0.05), but the cooling group showed no significant change in T2 throughout this study. Both groups showed a significantly decreased intracellular pH immediately after exercise (P < 0.05). After that, the cooling group showed a significantly greater value than the value at rest or the control group at 60 min after exercise (P < 0.05). For the Pi/PCr, no significant change was observed in both groups throughout this study. The muscle soreness level significantly increased immediately and at 24-48 h after exercise in both groups (P < 0.05). CONCLUSION: The findings of this study suggest that cooling causes an increase in intracellular pH and prevents the delayed muscle edema.

Adult↗
PubMed2003

[Changes in 1H-MRS in glioma patients before and after irradiation: the significance of quantitative analysis of choline-containing compounds].

The evaluation of the response to radiation therapy in brain tumor patients is a major and an important issue. Although CT and MRI can measure changes in tumor size, it is difficult to use these imaging methods to evaluate the viability or the proliferation activity of a tumor. In this study, we investigated the metabolite changes in glioma patients using 1H-MRS from before to after radiation therapy, to see whether or not early metabolic changes occur during therapy. Seven patients with histologically proven glioma (1 astrocytoma, 1 anaplastic astrocytoma, 2 oligoastrocytoma, 1 oligodendroglioma, 2 glioblastoma) were examined by means of 1H-MRS using a point-resolved spectroscopy (PRESS) sequence with a repetition time of 2,000 ms and echo times of 68 ms, 136 ms and 272 ms. The 1H-MRS was evaluated by both the spectrum pattern and the quantification of the metabolites. As to radiation therapy, each patient received a total dose of 64.8 Gy (1.8 Gy/fraction) with a 10-MeV linear accelerator. The results revealed that the concentration of choline-containing compounds (Cho) was 4.55 +/- 1.08 mmol/kg wet weight before radiation therapy and was reduced to 2.69 +/- 0.56 mmol/kg wet weight (p < 0.01) after radiation therapy. Moreover, both the N-acetylaspartate (NAA) peak and creatine/phosphocreatine (t-Cr) peak were lower after radiation therapy than before. The peaks of both the lipids (Lip) and lactate (Lac) were higher after radiation therapy than before. In conclusion, Cho concentration is thought to be a useful marker for the evaluation of early post-radiation response. The effect of radiation therapy can be evaluated according to the value of Cho. Further long-term MRS study is needed to prove whether or not the decrease of the Cho value in the present study will change before recurrence at later stages.

Adult↗
PubMed2002

Large-area phase-contrast X-ray imaging using a two-crystal X-ray interferometer.

Large-area (25 x 20 mm) phase-contrast X-ray imaging was attained by using a skew-symmetric two-crystal X-ray interferometer. The sub-nrad angular control required to operate the X-ray interferometer was achieved with a sleeve bearing and a feedback-positioning system. As a demonstration, measurements of a phase map of a rat's liver and a phase-contrast tomographic three-dimensional image of a piece of a rabbit's liver were performed at the Photon Factory using 0.07 nm synchrotron radiation X-rays.

Animals↗
PubMed2002

MR microscopy of articular cartilage at 1.5 T: orientation and site dependence of laminar structures.

OBJECTIVE: To evaluate MR microscopic images of normal-appearing porcine hyaline cartilage ( n=15) in vitro obtained with an MR microscope using an independent console system (MRMICS) at 1.5 T. DESIGN AND RESULTS: The MRMICS is a portable imaging system consisting of a radiofrequency system, gradient power supplies and a personal computer. The images from the MRMICS showed a laminar structure of porcine cartilage similar to the structure demonstrated with other MR imaging techniques. The laminar structures of the articular cartilage, were, however heterogeneous in respect of signal intensity and thickness, which varied according to the site resected. The MR laminar appearance was most comparable to the staining with Masson's trichrome for collagen. CONCLUSION: MRMICS is a useful add-on system for obtaining microscopic MR images of articular cartilage in vitro.

Animals↗
PubMed2002

Vessel imaging by interferometric phase-contrast X-ray technique.

BACKGROUND: Phase-contrast x-ray imaging using an x-ray interferometer has great potential to reveal the structures inside soft tissues, because the sensitivity of this method to hydrogen, carbon, nitrogen, and oxygen is approximately 1000 times higher than that of the absorption-contrast x-ray method. Imaging of vessels is very important to understand the vascular distribution of organs and tumors, so the possibility of selective angiography based on phase contrast is examined with a physiological material composed of low-atomic-number elements. METHODS AND RESULTS: Phase-contrast x-ray imaging was performed with a synchrotron x-ray source. Differences in refractive index, ddelta, of physiological saline, lactated Ringer's solution, 5% glucose, artificial blood such as pyridoxylated hemoglobin-polyoxyethylene conjugate, and perfluorotributylamine were measured. Because the ddelta of physiological saline has highest contrast, it was used for the phase-contrast x-ray imaging of vessel, and this was compared with absorption-contrast x-ray images. Vessels >0.03 mm in diameter of excised liver from rats and a rabbit were revealed clearly in phase-contrast x-ray imaging, whereas the vessel could not be revealed at all by the absorption-contrast x-ray image. Absorption-contrast x-ray images with iodine microspheres depicted only portal veins >0.1 mm in diameter with nearly the same x-ray dose as the present phase-contrast x-ray imaging. CONCLUSIONS: Phase-contrast x-ray imaging explored clear depiction of the vessels using physiological saline with small doses of x-rays.

Angiography↗
PubMed2002

Pitfalls in liver imaging.

Localized, abnormal attenuation/intensity areas on unenhanced and/or enhanced study of CT/MR imaging do not necessarily correspond to tumors themselves or real tumor size. Pitfalls in the diagnosis of liver tumor are described dividing into enhanced study (vascular variants, vascular abnormalities, hyperplastic nodules, around the tumor, and miscellaneous) and unenhanced study (fatty change, focal spared area of diffuse fatty liver, and miscellaneous).

Diagnosis, Differential↗
PubMed2002

Double arterial phase dynamic MRI with sensitivity encoding (SENSE) for hypervascular hepatocellular carcinomas.

PURPOSE: To investigate the efficacy of SENSE MRI, including the double arterial phase dynamic study, to detect hypervascular hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: MRI of the liver was performed in 40 consecutive patients (20 by conventional MRI and 20 by SENSE MRI). The SENSE technique was used to obtain breath-hold T1-weighted FSE images (TR/TE = 556/12 msec), respiratory-triggered T2-weighted FSE images (TR/TE = 1800/90 msec) with and without fat suppression, and dynamic MR images (TR/TE/FA = 160-168/4.6 msec/70 degrees ). In each arterial dominant phase and portal dominant phase, two scans were consecutively performed with one breath-hold, leading to the double arterial phase and double portal phase images with SENSE. RESULTS: The sensitivity of SENSE MRI for HCCs diagnosed from all MR images, including dynamic study, T1-weighted images, and T2-weighted images, was 91.7%, while that of conventional MRI was 76.3%. The positive predictive value of SENSE MRI for HCCs was 91.7%, while that of conventional MRI was 87.9%. In terms of HCCs < or = 10 mm, the sensitivity and positive predictive values of SENSE MRI were 78.6% and 78.6%, respectively, while those of conventional MRI were 27.3% and 60.0%, respectively. The number of detected HCCs < or = 10 mm was significantly larger in SENSE MRI than in conventional MRI (P < 0.05). The cause of false-positive lesions on SENSE MR images was an arterioportal shunt. CONCLUSION: SENSE MRI with double arterial phase dynamic study showed higher sensitivity compared to the conventional technique. Therefore, SENSE MRI is a promising method for the detection of HCC.

Carcinoma, Hepatocellular↗
PubMed2002

Assessment of cervical cancer radioresponse by serum squamous cell carcinoma antigen and magnetic resonance imaging.

OBJECTIVE: To investigate the possibility of objective clinical assessment of the radioresponse of cervical cancer via determination of serum squamous cell carcinoma antigen levels and magnetic resonance imaging (MRI)-based estimation of tumor shrinkage. METHODS: The cases of 60 patients undergoing definitive radiotherapy for cervical squamous cell carcinoma (stage I-II: n = 20; stage III-IV: n = 40) were reviewed. Measurements of serum squamous cell carcinoma antigen levels (n = 60), estimated tumor volume on preradiotherapy MRIs (n = 60), and evaluated tumor shrinkage on postradiotherapy MRIs available (n = 30) were taken. The relation between postradiotherapy squamous cell carcinoma antigen level 2 months after the start of radiotherapy and disease recurrence was investigated. Regression analysis of tumor volume measured on MRIs was used to estimate the extent of tumor shrinkage 2 months after the start of radiotherapy. RESULTS: Preradiotherapy squamous cell carcinoma antigen levels correlated significantly with preradiotherapy tumor volumes. Recurrence was identified in 27 patients as distant (n = 19), distant and local (n = 1), local (n = 5), or regional (n = 2). Of 51 patients with elevated preradiotherapy squamous cell carcinoma antigen levels, 33 achieved normalized levels after radiotherapy. Squamous cell carcinoma antigen normalization was associated with a higher recurrence-free survival rate at 2 years (74.3%) than that associated with nonnormalization of squamous cell carcinoma antigen (5.6%, P <.001). The extent of shrinkage ranged from 61% to 100%, and there was no local recurrence. CONCLUSION: Postradiotherapy squamous cell carcinoma antigen status is a useful indicator of clinical outcome, particularly about tumor recurrence. It is not, however, useful for assessing response to radiotherapy. Magnetic resonance imaging is useful for obtaining an objective assessment of radioresponse.

Antigens, Neoplasm↗