Takashi Katsube

Estimation of liver function using T1 mapping on Gd-EOB-DTPA-enhanced magnetic resonance imaging.

Objectives:To investigate the ability of T1 mapping of liver on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging for the estimation of liver function. Materials and Methods:Local institutional review board approved this study. Ninety-one patients (64 men, 27 women; mean age, 67.4 years) were classified into 4 groups as follows: normal liver function (NLF), n = 16; chronic hepatitis (CH), n = 38; liver cirrhosis with Child-Pugh A (LCA), n = 20; and liver cirrhosis with Child-Pugh B (LCB), n = 17. Look-Locker sequences (single slice multiphase imaging using gradient-echo sequence with inversion recovery pulse) were obtained before and at 3, 8, 13, and 18 minutes after Gd-EOB-DTPA administration. T1 mapping of liver parenchyma was calculated from the Look-Locker sequence. T1 relaxation time of liver and reduction rate of T1 relaxation time between pre- and postcontrast enhancement were measured. The Bonferroni t test was used for comparisons between the 4 groups. Results:Precontrast T1 relaxation times were significantly longer for LCA and LCB than for NLF, and that of LCB was longer than that of chronic hepatitis (P < 0.05). Postcontrast T1 relaxation times were significantly longer for LCB than for other groups at all time points. Those of LCA were longer than those of NLF at all time points. Reduction rates were significantly lower for LCB than for the other groups at ≥8 minutes. Conclusions:Evaluation of hepatic uptake of Gd-EOB-DTPA using T1 mapping of liver parenchyma can help estimate liver function.

Estimation of liver function using T2* mapping on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging

PURPOSE To investigate the usefulness of T2* mapping of liver on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI for estimating liver function. MATERIALS AND METHODS 33 patients were classified into 3 groups as follows: normal liver function (NLF) (n = 7); mild liver damage (MLD) (n = 16) with Child-Pugh A; severe liver damage (SLD) (n = 10) with Child-Pugh B. T2*-weighted gradient-echo (T2*W-GRE) and T1-weighted gradient-echo (T1W-GRE) images were obtained before and after Gd-EOB-DTPA administration (3, 8, 13, and 18 min; 5, 10,15, and 20min; respectively). T2* mapping of liver was calculated from T2*W-GRE, then T2* values of liver and T2* reduction rates of T2* value between pre- and post-contrast enhancement were measured. The increase rates of liver-to-muscle signal intensity (LMS) ratio on T1W-GRE between pre- and post-contrast enhancement were calculated. RESULTS T2* values on pre- and post-contrast showed no significant differences among three groups. Significant differences in T2* reduction rates were found among groups, and those of LCB were lower than those of other groups (NLF:MLD:SLD, 3.8:6.0:0.6% at 3 min, 8.2:10.3:1.0% at 8 min, 10.7:11.5:1.2% at 13 min, and 16.1:13.2:3.5% at 18 min, respectively) (P<0.05). Significant differences in increase rates of LMS ratio on T1W-GRE were identified (NLF:MLD:SLD, 1.53:1.46:1.35 at 5 min, 1.68:1.64:1.37 at 10 min, 1.79:1.76:1.44 at 15 min, and 1.89:1.78:1.49 at 20 min, respectively). CONCLUSION T2* reduction rate and increase rate of LMS ratio on T1W-GRE may allow us estimation of liver function according to Child-Pugh score.

Effect of the forward-projected model-based iterative reconstruction solution algorithm on image quality and radiation dose in pediatric cardiac computed tomography

BackgroundSome iterative reconstruction algorithms are useful for reducing the radiation dose in pediatric cardiac CT. A new iterative reconstruction algorithm (forward-projected model-based iterative reconstruction solution) has been developed, but its usefulness for radiation dose reduction in pediatric cardiac CT is unknown.ObjectiveTo investigate the effect of the new algorithm on CT image quality and on radiation dose in pediatric cardiac CT.Materials and methodsWe obtained phantom data at six dose levels, as well as pediatric cardiac CT data, and reconstructed CT images using filtered back projection, adaptive iterative dose reduction 3-D (AIDR 3-D) and the new algorithm. We evaluated phantom image quality using physical assessment. Four radiologists performed visual evaluation of cardiac CT image quality.ResultsIn the phantom study, the new algorithm effectively suppressed noise in the low-dose range and moderately generated modulation transfer function, yielding a higher signal-to-noise ratio compared with filtered back projection or AIDR 3-D. When clinical cardiac CT was performed, images obtained by the new method had less perceived image noise and better tissue contrast at similar resolution compared with AIDR 3-D images.ConclusionThe new algorithm reduced image noise at moderate resolution in low-dose CT scans and improved the perceived quality of cardiac CT images to some extent. This new algorithm might be superior to AIDR 3-D for radiation dose reduction in pediatric cardiac CT.

Optimal scanning protocol of arterial dominant phase for hypervascular hepatocellular carcinoma with gadolinium‐ethoxybenzyl‐diethylenetriamine pentaacetic acid‐enhanced MR

To investigate optimal delay time of hepatic arterial phase in Gadoxetate‐enhanced MR for detecting hypervascular hepatocellular carcinoma (HCC).

Demonstration of cerebellar atrophy in neuroacanthocytosis of 2 siblings.

SUMMARY: Neuroacanthocytosis is a rare hereditary disorder characterized by involuntary choreiform movements and erythrocytic acanthocytosis in the peripheral blood. Clinical manifestations of this disorder resemble those of Huntington disease (HD). Neuroimaging features of neuroacanthocytosis are atrophy and signal intensity change of the striata on MR imaging, as in HD. We report herein the cases of 2 siblings with neuroacanthocytosis showing cerebellar atrophy as well as atrophy and signal intensity changes of striata.

Computed diffusion-weighted imaging using 1.5-T magnetic resonance imaging for prostate cancer diagnosis.

Computed diffusion-weighted magnetic resonance imaging (cDWI) is gradually being known to be useful to detect prostate cancer. We found that cDWIs (b=2000 s/mm2) were easily generated from measured DWIs (mDWIs) with image processing using Image J and that the contrast ratio (CR) of cDWIs-2000 appeared to be higher than the CR of mDWIs-1000 and mDWIs-2000. The diagnostic ability of cDWI-2000 for prostate cancer detection was equivalent to that of mDWI-2000. There is a possibility that cDWIs-2000 can replace mDWIs-2000.

Assessment of Filtration Bleb and Endplate Positioning Using Magnetic Resonance Imaging in Eyes Implanted with Long-Tube Glaucoma Drainage Devices.

Background To evaluate ocular fluid filtration and endplate positioning in glaucomatous eyes with long-tube glaucoma drainage devices (GDDs) using magnetic resonance imaging (MRI) and the effects of various factors on postoperative intraocular pressure (IOP). Methods This observational case series included 27 consecutive glaucomatous eyes (18 men, 7 women; mean age ± standard error, 63.0±2.0 years) who underwent GDD implantation (n = 8 Ahmed Glaucoma Valves [AGV] and n = 19 Baerveldt Glaucoma Implants [BGI]). Tubes were inserted into the pars plana in 23 eyes and anterior chamber in 4 eyes. Six months postoperatively, high-resolution orbital images were obtained using 3-Tesla MRI with head-array coils, and the filtering bleb volume, bleb height, and distances between the anterior endplate edge and corneal center or limbus or between the endplate and orbital wall were measured. Results In MR images obtained by three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequences, the shunt endplate was identified as low-intensity signal, and the filtering bleb was identified as high-intensity signals above and below the endplate in all eyes. The 6-month-postoperative IOP level was correlated negatively with bleb volume (r = -0.4510, P = 0.0182) and bleb height (r = -0.3954, P = 0.0412). The postoperative IOP was significantly (P = 0.0026) lower in BGI-implanted eyes (12.2±0.7 mmHg) than AGV-implanted eyes (16.7±1.2 mmHg); bleb volume was significantly (P = 0.0093) larger in BGI-implanted eyes (478.8±84.2 mm3) than AGV-implanted eyes (161.1±52.3 mm3). Other parameters did not differ. Conclusions The presence of intraorbital/periocular accumulation of ocular fluid affects postoperative IOP levels in eyes implanted with long-tube GDDs. Larger filtering blebs after BGI than AGI implantations explain lower postoperative IOP levels achieved with BGI than AGV. The findings will contribute to better understanding of IOP reducing mechanism of long-tube GDDs.

Does applying resolution recovery to normal databases confer an advantage over conventional 3D-stereotactic surface projection techniques?

We evaluated a novel normal database (NDB) generated using single photon emission computed tomography (SPECT) data obtained from healthy brains by using a SPECT/CT system, analyzed using a resolution recovery (RR) technique applied to the three-dimensional stereotactic surface projection (3D-SSP) technique. We used a three-dimensional ordered subset expectation maximization method (3D-OSEM) with applied scatter correction (SC), attenuation correction, and RR to reconstruct the data. We verified the accuracy of the novel NDB’s values (Z, extent, and error scores), and compared the novel NDB to the 3D-SSP technique by using simulated misery perfusion-related patient data from a conventional NDB. In addition, Z, extent, and error scores at the precuneus, cuneus, and posterior cingulate were compared under different reconstruction conditions by using the patient data. In the simulation, Z scores decreased when using the novel NDB corrected using computed tomography-based attenuation correction (CTAC), SC, and RR. The extent scores of the posterior cingulate increased using the novel NDB, relative to the other NDBs. The error score with the novel NDB without RR decreased by 15% compared to that of the conventional NDB. Z scores generated from patient data decreased in the novel NDB with RR. The extent scores tended to decrease in the novel NDB with RR. The extent scores in the novel NDB with RR improved at the posterior cingulate, compared to the scores with the other NDBs. However, applying RR to the novel NDB conferred no advantage because the cut-off of the current Z score must be reconsidered when using the additive RR technique.

T2* relaxometry mapping of the uterine zones:

Background Previous literature demonstrated that the T2* value of the uterine junctional zone was lower than that of peripheral myometrium by using BOLD MR imaging. We expect T2* mapping image may add more information to T2-weighted images of the uterine myometrium. Purpose To evaluate whether T2* mapping software would reproduce the result of previous report, and to apply the software to benign uterine diseases. Material and Methods Five healthy volunteers and 19 patients clinically suspected of having benign pelvic disease were imaged using a 1.5T MR system. All women were of reproductive age, and all provided informed consent. Sagittal T2* images using a multishot EPI sequence were obtained. T2* values were calculated and color T2* maps reconstructed using a T2* fitting tool. Results The uterine zones could be identified in all 24 examinations on the T2* maps. In addition, a thin “4th zone” was seen between the endometrium and the JZ (junctional zone) in 19 of 24 examinations. The T2* value of JZ was significantly lower than that of peripheral myometrium (PM) (P < 0.001). No significant difference in the T2* value of the JZ or of PM was noted between normal uterus and uterus with leiomyomas and/or adenomyosis. Conclusion A quantitative T2* map can easily be obtained using the PRIDE software T2* fitting tool, and the software reproduces the result from previous report. T2* value of the junctional zone was lower than that of peripheral myometrium regardless of having benign myometrial diseases.

Unenhanced fat fraction ratios obtained by MR and enhanced T2* values with liver-specific MR contrast agents for diagnosis of non-alcoholic steatohepatitis in rats

Background Non-invasive MR imaging is expected to be used for accurate diagnosis and quantification of non-alcoholic steatohepatitis (NASH), because NASH is a progressive fatty liver disease. New MR techniques, such as fat fraction ratio (FFR) and T2* value measurement, have attracted an increasing attention, because those techniques can measure quantitative parameters of fibrosis, fat and iron deposition in the liver. Purpose To investigate the potential of FFR and T2* value in NASH with pre-enhancement, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) or super-paramagnetic iron oxide (SPIO)-enhanced MRI. Material and Methods Twenty-eight rats were divided equally into four groups (one control group and three NASH groups). All rats underwent unenhanced, Gd-EOB-DTPA, and SPIO-enhanced MRI. The T2* value of the liver was measured for each image sequence, and then changes in T2* values before and after each injection were analyzed using Dunnetts test. The reduction rate of T2* value before and 13 min after injection of Gd-EOB-DTPA or SPIO was analyzed using Mann-Whitneys U test. Moreover, FFR of the liver was measured before enhancement, and the relationship between fat fraction and the calculated fat area percentage on a pathological specimen was examined using Spearmans correlation test. Results On pre-enhancement, FFR and T2* value were 26.0% ± 12.0% and 21.5 ± 4.2 ms for all NASH groups, and 0.9% ± 0.5% and 30.8 ±−5.5 ms for control, respectively. Both FFR and T2* values were significantly different between the NASH and control groups. The reduction rate of T2* value was significantly lower in the NASH groups than in the control group on SPIO-enhanced MRI, though there was no significant difference on Gd-EOB-DTPA-enhanced MRI. FFR was correlated with the calculated fat area percentage for the pathological specimen. Conclusion Pre-enhancement FFR, T2* value measurement and reduction rate of T2* value on SPIO-enhanced MRI may help estimate the progress of liver fat deposition and fibrosis in NASH.