Takayuki Masui

Diffusion-weighted echo planar imaging of ovarian tumors: is it useful to measure apparent diffusion coefficients?

Purpose Our goal was to test the hypothesis, as previously reported in other studies, that apparent diffusion coefficients (ADCs) provide specific information to diagnose ovarian tumors, especially to discriminate between benign and malignant lesions. Method T1-and T2-weighted spin echo imaging and diffusion-weighted echo planar imaging were performed in 31 women with 61 cystic components of ovarian tumors. Results The lesions that showed typical watery intensity, hypointensity in T1-weighted imaging, and hyperintensity in T2-weighted imaging had similar ADCs, ranging from 1.54 to 1.84 × 10−3 mm2 /s. The lesions that showed signal intensity different from typical watery intensity in conventional MRI tended to have low ADCs. In endometrial cysts, the mean ADC of the subgroup that showed typical watery intensity was higher than that of other subgroups. Conclusion With conventional MRI, a tendency of ADCs could be predicted. ADCs may not provide additional information, especially to discriminate benign from malignant lesions.

Assessment of right ventricular diastolic and systolic function in patients with dilated cardiomyopathy using cine magnetic resonance imaging

Cine magnetic resonance imaging (MRI) can provide clear endocardial margins of the entire right ventricle, and Simpsons algorithm can be applied to obtain the volumes at multiple phases of the cardiac cycle. Time-volume curves of the right ventricle were obtained by using cine MRI in 10 patients with dilated cardiomyopathy (DCM) and eight normal volunteers to assess right ventricular function. There were no significant differences in volumes and ejection fraction of the right ventricle between the group with DCM and the normal group. In the group with DCM the time to peak filling rate was increased (p less than 0.05) and the filling fraction was decreased (p less than 0.01). In the patients with DCM cine MRI demonstrated normal volumes and ejection fraction of the right ventricle in contradistinction to the marked increase in volumes and the decrease in ejection fraction of the left ventricle; with the use of time-volume curves of the right ventricle, impairment of diastolic function of the right ventricle was demonstrated.

Gadolinium‐enhanced MR angiography in the evaluation of congenital cardiovascular disease pre‐ and postoperative states in infants and children

The purpose of this study was to evaluate the utility of dynamic contrast magnetic resonance (MR) angiography under sedation for assessing congenital cardiovascular disease in infants and small children before and after cardiac surgery. In 38 patients with cardiovascular abnormalities, thoracic vasculatures were evaluated in either the preoperative (group 1; 23 patients, median age 9 months old) or the postoperative (group 2; 15 patients median age 1.3 years old) state using gadolinium‐enhanced dynamic MR angiography. Acquired data were processed with a multiprojection volume reconstruction. Image quality (grades 1–5, undiagnostic to excellent), presence or absence of the extracardiac vasculature, its pathology (group 1), and the patency of the postsurgical shunt or reconstructed vasculature (group 2) were evaluated. All images were of diagnostic image quality (mean grade 4.4–3.2). Recognition of the thoracic vasculature was correctly made in all cases (38/38, 100%). In group 1, anomalies and pathologic changes were correctly identified in 22 of 23 cases (95.7%). In one patient with dextrocardia and the cardiac type of total anomalous pulmonary venous return, the abnormality was not recognized. In group 2, the patency of the shunt flow after Glenn (n = 6), modified Fontan (n = 4), Rastelli (n = 1), and Blalock‐Taussig (n = 3) operations was well demonstrated in each case. The reconstructed pulmonary artery (n = 1), veins (n = 2), and aorta (n = 1) were correctly visualized. In one case, stenosis of the reconstructed left pulmonary vein was missed by MR angiography. In 14 of 15 cases in group 2 (93.3%), MR angiography correctly gave information on the operated areas. In conclusion, dynamic contrast MR angiography under sedation is useful for evaluation of the thoracic vasculature of infants and small children in the pre‐ and postoperative states. J. Magn. Reson. Imaging 2000;12:1034–1042.

Fat-suppressed T2-weighted MRI of the liver: Comparison of respiratory-triggered fast spin-echo, breath-hold single-shot fast spin-echo, and breath-hold fast-recovery fast spin-echo sequences

The purpose of our study was to compare the value of respiratory‐triggered fast spin‐echo, breath‐hold single‐shot fast spin‐echo, and breath‐hold fast‐recovery fast spin‐echo sequences in detecting hepatic lesions. Fat‐suppressed T2‐weighted magnetic resonance (MR) images obtained with the three sequences in 36 patients with 138 lesions and nine patients without lesions were prospectively analyzed. Quantitative and qualitative analyses, including receiver operating characteristic (ROC) analyses, were performed. The mean lesion‐to‐liver contrast‐to‐noise ratio (CNR) for hepatic lesions was highest with the respiratory‐triggered fast spin‐echo sequence. On the basis of receiver‐operating characteristic analyses, tumor detection rates were higher with the breath‐hold fast‐recovery fast spin‐echo sequence (Az = 0.94) than with the respiratory‐triggered fast spin‐echo sequence (AZ = 0.80, P < 0.0001) or the single‐shot fast spin‐echo sequence (Az = 0.77, P < 0.0001). The image quality with the breath‐hold fast‐recovery fast spin‐echo sequence was acceptable in all patients. The breath‐hold fast‐recovery fast spin‐echo sequence provided the highest tumor detection in a short imaging time, although the mean lesion‐to‐liver CNRs were inferior to those of the respiratory‐triggered fast spin‐echo and the breath‐hold single‐shot fast spin‐echo sequences. J. Magn. Reson. Imaging 2001;14:439–449.

Magnetic resonance cholangiopancreatography: comparison of respiratory-triggered three-dimensional fast-recovery fast spin-echo with parallel imaging technique and breath-hold half-Fourier two-dimensional single-shot fast spin-echo technique.

PurposeThe aim of this study was to compare magnetic resonance cholangiopancreatography (MRCP) using respiratory-triggered (resp) three-dimensional Fourier transformation (3D) fast-recovery fast spin echo (FR-FSE) sequence with array spatial sensitivity technique (ASSET) for visualization of the pancreatobiliary system with breath-hold single thick-section and multiple thin-section MRCP using 2D single shot FSE (SSFSE) sequences.Materials and methodsForty patients underwent MRCP for evaluation of pancreatobiliary abnormalities in a 1.5-T magnet. Imaging time for resp 3D FR-FSE was recorded. The ghosting and blurring artifacts, overall image quality, and delineation of the pancreatobiliary ducts were evaluated using a five-point scale.ResultsOn multisection 2D SSFSE source images, there were the least ghosting artifacts (4.9 ± 0.3, P < 0.05). Ghosting (3.4 ± 0.6, P < 0.05) and blurring (4.4 ± 0.8; P < 0.05) artifacts were the most prominent on resp 3D FR-FSE. 3D FR-FSE MRCP provided the highest rating of overall image quality (4.3 ± 0.8, P < 0.05) and delineation of third- and second-order branches of the hepatic ducts (2.9 ± 1.6 for third-order branches and 3.9 ± 1.3 for second-order branches, P < 0.05). Extrahepatic bile ducts, including upper and middle portions and cystic and pancreatic ducts, were also better seen with resp 3D FR-FSE MRCP than others.ConclusionMRCP with resp 3D FR-FSE using ASSET can be routinely used for acquiring information from the pancreatobiliary system.

Intravenous injection of high and medium concentrations of computed tomography contrast media and related heat sensation, local pain, and adverse reactions

Objectives: To evaluate the incidence of acute adverse reactions and degrees of heat sensation and local pain after intravenous injection of high and medium concentrations of iodinated contrast medium for computed tomography (CT). Methods: A prospective study was performed involving 729 patients who underwent contrast CT scans. High-concentration (370 mgI/mL) and medium-concentration (300 mgI/mL) iodinated contrast medium was assigned to 342 patients (group H, aged 20-90 years, mean = 59.8 years) and to 387 patients (group M, aged 20-95 years, mean = 61.7 years), respectively. An injection rate of contrast medium (1, 2, or 4 mL/s) at a base volume of 2 mL/kg of body weight was selected according to the protocols for the evaluated diseases and regions. Each patient was assessed for heat sensation and local pain at the injection site using a visual analog scale (ranging from none for 0 to severe for 10). Acute adverse reactions were recorded when they occurred. Results: There were no significant differences in patient background factors, including age, sex, history of prior adverse reactions, and allergies, between the 2 groups. The score for heat sensation was significantly higher in group H than in group M (4.46 ± 2.44 vs. 3.44 ± 2.45; P < 0.0001 for heat sensation). The data did not show a higher incidence of adverse reactions in group H than in group M (5 [1.46%] of 342 patients vs. 2 [0.52%] of 387 patients; P = 0.26) or a higher score for local pain in group H than in group M (0.98 ± 1.70 vs. 0.88 ± 1.49; P = 0.66), respectively. Conclusions: High and medium concentrations of iodinated contrast medium can be used for CT study with comparable safety profiles even though heat sensation produced by the high-concentration CM is greater than that produced by the medium-concentration CM.

Effect of cilazapril on regional left ventricular wall thickness and chamber dimension following acute myocardial infarction: In vivo assessment using MRI

The primary goal of the current study was to assess in situ, using magnetic resonance imaging, the effect of a new angiotensin-converting enzyme inhibitor, cilazapril, in reducing left ventricular remodeling after acute myocardial infarction. Three groups of animals were investigated: (1) sham-operated rats (n = 19); (2) infarcted rats receiving no treatment (n = 23); and (3) infarcted rats receiving cilazapril (100 mg/L drinking water, n = 20). Treatment with cilazapril began on the third day postocclusion and continued for 3 to 4 months. Myocardial infarction was produced by ligation of the left coronary artery, and electrocardiographic (ECG)-gated short-axis images were acquired 3 to 4 months later. Sham-operated animals were subjected to the same procedure but the left coronary artery was not ligated. From the image acquired in the middle of the left ventricle (equatorial slice), left ventricular wall thicknesses, chamber diameters, and surface area measurements of the cavities were determined. At autopsy examination, infarct size and tissue water content were determined. The results demonstrate that magnetic resonance imaging has the potential to assess in situ the alterations of left ventricular dimensions and mass after acute myocardial infarction and can be used to document the influence of therapeutic interventions. Cilazapril provided protection against the deleterious remodeling changes such as ventricular dilation and wall thinning consequent to acute myocardial infarction.

T2‐weighted MRI of the female pelvis: Comparison of breath‐hold fast‐recovery fast spin‐echo and nonbreath‐hold fast spin‐echo sequences

In 49 patients who had pelvic abnormalities, breath‐hold T2‐weighted fast‐recovery (FR)‐fast spin‐echo (FSE) (imaging time = 24 sec) and nonbreath‐hold FSE MR images (2 min 8 sec) were compared qualitatively (on a four‐point scale) and quantitatively (using signal‐to‐noise ratios (SNRs) and contrast ratios (| SIs of the lesions‐SIs of the myometrium | /SIs of the myometrium)). Motion artifacts were reduced on breath‐hold FR‐FSE (3.8:3.2 = breath‐hold FSE:nonbreath‐hold FSE, P < 0.01) and image quality was comparable (3.8:3.7, NS). In all patients, pathology (leiomyoma [N = 26], adenomyosis [N = 10], endometrial carcinoma [N = 8], and ovarian cystic lesions [N = 21]) was recognized with comparable lesion conspicuity (3.8:3.7, NS) and better delineation of the structures (3.9:3.6, P < 0.05) on the FR‐FSE images. There was no significant difference in contrast ratios, although SNRs (e.g., myometrium 18.3:25.8, P < 0.01) were better and the uterine zonal anatomy was recognized better on the nonbreath‐hold FSE (3.4:3.7, P < 0.05). These differences did not affect the diagnosis. Breath‐hold FR‐FSE provides the benefits of motionless imaging and a short examination time, although lower SNRs were noted. J. Magn. Reson. Imaging 2001;13:930–937.

Functional assessment of pancreatic parenchyma after secretin administration using serial T2-weighted echo-planar magnetic resonance imaging.

Signal intensity (SI) changes of pancreatic parenchyma were evaluated after intravenous administration of secretin using T2‐weighted single‐shot spin‐echo echo‐planar imaging (EPI) to assess this method as a magnetic resonance (MR) test of pancreatic exocrine function. Nine volunteers were studied with serial single‐shot EPI of the pancreas for 15 minutes after the injection of secretin or saline. The normal pattern of pancreatic SI change was demonstrated after intravenous injection of secretin, a single peak at 3–4 minutes in the head, body, and tail, followed by a gradual decrease in SI. Saline injection did not induce a significant SI change. There was no statistical difference in the peak contrast ratios (first mean, 1.21–1.25, vs. second mean, 1.18–1.22) and peak times (first mean, 3.2–3.7 minutes, vs. second mean, 3.1–3.6) in a repeat study. By evaluating the pattern of time‐response curves obtained from serial T2‐weighted EPI after secretin injection, pancreatic exocrine function may be directly assessed at the level of the head, body, and tail. J. Magn. Reson. Imaging 2001;14:450–456.

Epithelioid Hemangioendothelioma of the Liver: Imaging Diagnosis of a Rare Hepatic Tumor

were within normal limits. Abdominal computed tomography (CT) demonstrated multiple round or oval areas of low density with intratumoral calcifi cation, mostly along the margins of the liver ( fi g. 1 a). Contrast-enhanced CT showed dense enhancement all around the tumors. CT during hepatic arteriography (CTHA) demonstrated target-like lesions, that is, a central low-density area with a A 50-year-old man with multiple liver tumors mimicking metastatic carcinoma on imaging studies was admitted for further evaluation. On admission, the results of laboratory examinations were normal, except for an elevated -glutamyl transpeptidase concentration (124 IU/l). Tumor markers, including carcinoembryonic antigen, carbohydrate antigen 19-9, and -fetoprotein Published online: February 9, 2006