Katsuya Takahama

Delayed hyper-enhancement of myocardium in hypertrophic cardiomyopathy with asymmetrical septal hypertrophy: comparison with global and regional cardiac MR imaging appearances.

To evaluate the relationship between delayed hyper‐enhancement of the myocardium and global and regional cardiac abnormalities in hypertrophic cardiomyopathy (HCM) with asymmetrical septal hypertrophy using magnetic resonance (MR) imaging.

Non–contrast-enhanced MR angiography of the thoracic aorta using cardiac and navigator-gated magnetization-prepared three-dimensional steady-state free precession

To assess the usefulness of non–contrast‐enhanced MR angiography using cardiac and navigator‐gated magnetization‐prepared three‐dimensional (3D) steady‐state free precession (SSFP) imaging for the diagnosis of diseases of the thoracic aorta.

Detection and characterization of focal liver lesions using superparamagnetic iron oxide-enhanced magnetic resonance imaging: comparison between ferumoxides-enhanced T1-weighted imaging and delayed-phase gadolinium-enhanced T1-weighted imaging

AbstractBackground: Double contrast magnetic resonance (MR) imaging using superparamagnetic iron oxide (SPIO) and gadolinium (Gd) is performed to detect and characterize focal liver lesions. However, this technique is a costly and lengthy process. The purpose of this study was to determine the usefulness of SPIO-enhanced MR imaging including SPIO-enhanced T1-weighted imaging in diagnosing focal liver lesions. Methods: Eighty-four focal liver lesions were examined with a 1.5-T MR unit. Transverse precontrast T1- and T2-weighted images and SPIO (ferumoxides)-enhanced T1- and T2-weighted images were obtained, followed by Gd-enhanced T1-weighted imaging. The Gd set (i.e., precontrast T1- and T2-weighted and delayed-phase gadolinium-enhanced T1-weighted images) and ferumoxides set (i.e., precontrast T1- and ferumoxides-enhanced T1- and T2-weighted images) were reviewed by two independent readers. Results: More lesions were detected from the ferumoxides set than from the Gd set. Ferumoxides-enhanced T1-weighted imaging showed enhancement patterns of the lesions similar to those of delayed-phase Gd-enhanced T1-weighted imaging. The diagnoses of hepatic metastasis and cyst by the ferumoxides set were similar to those by the Gd set. However, a dynamic study may be inevitable for the diagnosis of hepatocellular carcinoma and hemangioma. Conclusion: The ferumoxides set was useful for the detection of focal hepatic lesions. Ferumoxides-enhanced T1-weighted imaging may replace delayed-phase gadolinium-enhanced T1-weighted imaging in the diagnosis of hepatic metastasis and cysts.

Magnetic resonance portography using contrast-enhanced fat-saturated three-dimensional steady-state free precession imaging.

To assess the feasibility of contrast‐enhanced fat‐saturated three‐dimensional steady‐state free precession (FIESTA) imaging for contrast‐enhanced magnetic resonance (MR) portography.

Noncontrast-enhanced three-dimensional magnetic resonance aortography of the thorax at 3.0 T using respiratory-compensated T1-weighted k-space segmented gradient-echo imaging with radial data sampling: preliminary study.

Objective:To evaluate the feasibility of a respiratory-compensated three-dimensional (3D) T1-weighted k-space segmented gradient-echo imaging sequence with radial data sampling for noncontrast-enhanced 3D magnetic resonance (MR) aortography of the thorax at 3.0 T. Materials and Methods:Twenty-two subjects, including healthy volunteers (n = 6) and patients with suspected diseases of the thoracic aorta (n = 16), underwent noncontrast-enhanced 3D MR aortography at 3.0 T acquired using a navigator- or respiratory-gated 3D T1-weighted k-space segmented gradient-echo imaging sequence with radial data sampling (TR, 4.8 milliseconds; TE, 1.5 milliseconds; flip angle, 20 degrees; spatial resolution 0.66 × 0.76 × 5.6–6.4 mm) in the sagittal oblique imaging plane. ECG gating, fat-suppression, and T2-prepared pulses were employed. The vascular contrast of the thoracic aorta and the contrast ratio between the aorta and the superior vena cava or pulmonary artery were compared between the noncontrast-enhanced 3D MR aortography and transverse two-dimensional (2D) steady-state free precession. Image quality of the noncontrast-enhanced 3D MR aortography was rated on a 4 point scale (1, nondiagnostic, to 4, diagnostic and excellent image quality). Results:The noncontrast-enhanced 3D MR aortography provided vascular contrast of the thoracic aorta comparable to, and contrast ratio between the aorta and superior vena cava higher than, those of 2D steady-state free precession. The mean score of image quality of the noncontrast-enhanced 3D MR aortography was 3.0 (diagnostic with no or few artifact), and some major branch arteries were visualized by this imaging. Conclusion:Respiratory-compensated 3D T1-weighted k-space segmented gradient-echo imaging with radial data sampling are feasible for the noncontrast-enhanced 3D MR aortography of the thorax at 3.0 T.

Fat-suppressed three-dimensional MR angiography technique with elliptical centric view order and no prolonged breath-holding time

To determine the appropriate rate of fat‐suppression pulses (using spec IR—spectral selective inversion recovery) for fat‐suppressed 3D magnetic resonance angiography (MRA) with an elliptical centric view order.

Assessment of renal impairment by non-contrast-enhanced conventional magnetic resonance imaging: comparison with 99mTc-DTPA renography

PurposeThe aim of this study was to determine whether non-contrast-enhanced magnetic resonance imaging (MRI) can detect three levels of renal impairment by evaluating the differences and agreement with 99mTc-diethylenetriamine pentaacetic acid (DTPA) renography.Materials and methodsA total of 28 patients with kidney disease were enrolled in the study. MRI findings, including visual corticomedullary differentiation (CMD) on T1- and T2-weighted imaging (T1WI, T2WI), cortical irregularity, the number of renal cysts, and the volume of the kidney, were evaluated for individual kidneys and pairs of kidneys. The differences and agreement between MRI findings and the three levels of renal impairment based on the glomerular filtration rate (GFR) measured using 99mTc-DTPA renography were analyzed.ResultsAll MRI findings except the number of renal cysts in pairs of kidneys were consistent with the patient’s classification. The agreement between the patient’s classifi cations based on GFR and that based on the visual CMD on T1WI and T2WI was almost perfect or substantial in both individual kidneys and pairs of kidneys.ConclusionNon-contrast-enhanced MRI was capable of distinguishing three levels of renal function, including serious renal impairment.

Contrast-enhanced T1-weighted black-blood fast spin-echo MR imaging of the brain. Technique for suppression of enhancing venous signal.

Purpose: Contrast-enhanced T1-weighted black-blood fast spin-echo MR imaging (BB-FSE) was performed to suppress enhancing venous signal and flow artifacts in the brain without sacrificing the T1-weighted imaging contrast. Material and Methods: Twenty-five MR imaging sections (17 transverse and 8 coronal images) in 15 patients with various brain diseases were obtained by contrast-enhanced T1-weighted SE and BB-FSE images. Results: In contrast-enhanced T1-weighted BB-FSE images, venous signal was significantly less and T1-weighted contrast of the brain was more evident. No differences in flow artifacts were found between the two imaging techniques. The interobserver agreements were good for the venous signal and flow artifacts using both techniques. Conclusion: Contrast-enhanced T1-weighted BB-FSE imaging reduced the venous signal in the brain with maintaining T1-weighted contrast. This novel MR technique can be used when the suppression of enhancing venous signal is expected to improve the depiction of enhancing lesions in the brain.

Centrally fat-saturated three-dimensional magnetic resonance angiography of the abdomen using selective central fat-saturation of k-space.

To assess the usefulness of centrally fat‐saturated three‐dimensional magnetic resonance (MR) angiography of the abdomen using an elliptical centric view order and selective placement of fat‐saturation pulses in the central 30% portion of the k‐space in terms of fat signal reduction, image contrast of post‐contrast images, and breath‐holding time.