Eito Kozawa

Noninvasive Evaluation of Kidney Hypoxia and Fibrosis Using Magnetic Resonance Imaging

Interstitial fibrosis and hypoxia accelerate the progression of CKD, but clinical tools to quantitate these factors in patients are lacking. Here, we evaluated the use of two magnetic resonance imaging (MRI) techniques, diffusion-weighted (DW)-MRI and blood oxygen level-dependent (BOLD)-MRI, to assess kidney fibrosis and hypoxia of the cortex in 142 patients with either diabetic nephropathy (n = 43), CKD without diabetes (n = 76), or acute kidney injury (AKI) (n = 23). Apparent diffusion coefficient (ADC) values of DW-MRI correlated with estimated glomerular filtration rates (eGFR) in the diabetic nephropathy and CKD groups (r(2) = 0.56 and r(2) = 0.46, respectively). Although the T2* values of BOLD-MRI and eGFR displayed good correlation in the CKD group (r(2) = 0.38), we did not observe a significant correlation between these values in the diabetic nephropathy group, suggesting that factors other than tubulointerstitial alteration determine the degree of hypoxia in the renal cortex. In the AKI group, neither the T2* nor ADC values correlated with eGFR. Renal biopsies from patients with CKD demonstrated that the T2* and ADC MRI values correlated with renal pathology. Taken together, ADC and T2* values appear to serve as accurate indices for evaluating renal tubulointerstitial alterations and parenchymal hypoxia, respectively, in the cortex. Functional MRI can thus contribute to multilateral, noninvasive, in vivo assessment of kidney function.

Vertebral artery variations at the C1–2 level diagnosed by magnetic resonance angiography

IntroductionThe craniovertebral junction is clinically important. The vertebral artery (VA) in its several variations runs within this area. We report the prevalence of these VA variations on magnetic resonance angiography (MRA).MethodsWe retrospectively reviewed MRA images, obtained using two 1.5-T imagers, of 2,739 patients, and paid special attention to the course and branching of the VA at the level of the C1–2 vertebral bodies.ResultsThere were three types of VA variation at the C1–2 level: (1) persistent first intersegmental artery (FIA), (2) VA fenestration, and (3) posterior inferior cerebellar artery (PICA) originating from the C1/2 level. The overall prevalence of these three variations was 5.0%. There was no laterality in frequency, but we found female predominance (P < 0.05). We most frequently observed the persistent FIA (3.2%), which was sometimes bilateral. We found VA fenestration (0.9%) and PICA of C1/2 origin (1.1%) with almost equal frequency. Two PICAs of C1/2 origin had no normal VA branch.ConclusionsWe frequently observed VA variations at the C1–2 level and with female predominance. The persistent FIA was most prevalent and sometimes seen bilaterally. Preoperative identification of these variations in VA is necessary to avoid complications during surgery at the craniovertebral junction.

Persistent trigeminal artery and its variants on MR angiography

IntroductionA persistent trigeminal artery (PTA) is the most common carotid-vertebrobasilar anastomosis. A cerebellar artery that arises from the precavernous segment of the internal carotid artery (ICA) without connecting to the basilar artery is regarded as a PTA variant. Our study aimed to determine the incidence of PTA and its variants and classify them based on magnetic resonance (MR) angiography.MethodsWe retrospectively reviewed cranial images of 3,626 patients who underwent MR angiography in our institution from April 1, 2007 through December 31, 2009. We ultimately reviewed and analyzed images of 3,491 patients (2,066 men, 1,425 women) after excluding 135 with unilateral or bilateral ICA occlusion or suboptimal image quality.ResultsWe found 12 cases of PTA (7 men, 5 women; right 4, left 8; incidence; 0.34%) and 6 of PTA variants (3 men, 3 women; right 3, left 3; incidence; 0.17%). 11 of the 12 PTAs were lateral type; 1 was medial. In two of the lateral-type cases, the superior cerebellar artery (SCA) arose from the PTA. Among the six variants, the anterior inferior cerebellar artery (AICA) arose in five and the posterior inferior cerebellar artery (PICA), in one.ConclusionsOn MR angiography, the incidence of PTA was 0.34% and of PTA variants, 0.17%. Left PTA was twice as frequent as right PTA, but with no statistical significance. Medial-type PTA was extremely rare. AICA arose in most PTA variants. Rarely, a lateral-type PTA gave rise to the cerebellar artery.

Fenestrations of the intracranial vertebrobasilar system diagnosed by MR angiography

IntroductionFenestrations of cerebral arteries are most common in the vertebrobasilar (VB) system, and magnetic resonance (MR) angiographic studies of these variations are sparse.MethodsWe retrospectively reviewed MR angiographic images of 3,327 patients; images were obtained using two 1.5-T imagers and picked up fenestrations of the intracranial vertebral artery (VA), VB junction, and basilar artery (BA) for evaluation.ResultsIn 92 patients, we found 93 fenestrations (2.80%), which included 18 of the intracranial VA (0.54% prevalence), 6 of the VB junction (0.18%), and 69 of the BA (2.07%). Most VA fenestrations were large, and the posterior inferior cerebellar artery arose from the fenestrated segment in 10 patients (56%). Fenestrations of the VB junction were small and triangular. Sixty-five (94%) of the 69 BA fenestrations were located at the proximal segment and had small slit-like configurations. The anterior inferior cerebellar artery arose from the fenestrated segment in 27 patients (37%). We found 18 cerebral aneurysms in 16 (17%) of the 92 patients with fenestration but detected only one aneurysm at the fenestration.ConclusionThe overall prevalence of fenestrations of the intracranial VB system was 2.77%. We found associated cerebral aneurysms relatively frequently but rarely at the fenestration.

Usefulness of diffusion-weighted imaging of breast tumors: quantitative and visual assessment

PurposeWe evaluated the usefulness of quantitative and visual assessment of diffusion-weighted imaging (DWI) of breast tumors to distinguish malignant from benign tumors.Materials and methodsThe DWI findings of 106 breast lesions (15 benign, 91 malignant) were retrospectively analyzed. The mean apparent diffusion coefficient (ADC) value for each lesion was calculated using b values of 250, 500, 750, and 1000 s/mm2 as a quantitative assessment. We visually evaluated the signal intensity of each breast lesion on the basis of a spinal signal intensity in DWI (b = 1000 s/mm2) and compared the mean ADC values using a threshold mean ADC +1.65 × standard deviation (SD) for malignant and benign breast lesions. Obviously strong signal intensity of the lesion relative to that of the spinal cord on DWI signifies malignancy.ResultsThe mean ADC value for benign lesions (1.50 ± 0.38 × 10−3 mm2/s) was significantly higher than that for malignant lesions (0.98 ± 0.19 × 10−3 mm2/s), with 94.5% sensitivity, 80% specificity, and 92.5% accuracy. Sensitivity for visual assessment was 91.5%, specificity was 33.3%, and total accuracy was 82.5%.ConclusionADC values, but not visual assessment, may be useful for differentiating benign and malignant breast tumors.

Utility of histogram analysis of apparent diffusion coefficient maps obtained using 3.0T MRI for distinguishing uterine carcinosarcoma from endometrial carcinoma

We explored the role of histogram analysis of apparent diffusion coefficient (ADC) maps for discriminating uterine carcinosarcoma and endometrial carcinoma.

Persistent primitive olfactory artery: MR angiographic diagnosis

IntroductionPersistent primitive olfactory artery (PPOA) is a relatively rare variation of the proximal anterior cerebral artery (ACA) that generally follows an extreme anteroinferior course and takes a hairpin turn. To our knowledge, incidence of PPOA has not been reported, so we researched cases in our institution records to determine incidence and investigated characteristic features of the condition on MR angiography.MethodsTo isolate cases with PPOA, we retrospectively reviewed cranial magnetic resonance (MR) angiographic images of a total of 3,626 patients in our institution and collected similar images from cases with PPOA from our two affiliated hospitals.ResultsWe found 14 cases with PPOA (six men and eight women); 5 patients in our institution, representing an incidence of 0.14%, and 9 cases from our group hospitals. The location was on the right in six cases, left in seven, and bilateral in one. An aneurysm was found at the hairpin turn in one patient, and in another patient, the PPOA connected with the accessory middle cerebral artery (MCA) and not the distal ACA.ConclusionsIn our institution, incidence of PPOA on MR angiography was 0.14%. We found no laterality in frequency and rare bilaterality, aneurysm at the point of the hairpin turn, and accessory MCA arising from the PPOA.

Is there no future for renal BOLD-MRI?

To the Editor: We read with interest the recent article by Michaely et al. in which it was stated that renal blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) does not reflect renal function in chronic kidney disease (CKD), a conclusion that is in direct contrast to our recent results. We strongly support the statement from the same issue that renal tissue oxygenation appears to be dependent on CKD severity as well as on the etiology of the underlying kidney disease. The causes of chronic renal hypoxia are remarkably multifactorial, and while we have verified a relationship between BOLD-MRI T2* values and estimated glomerular filtration rates in nondiabetic nephropathy, no association has been shown in cases of diabetic nephropathy. Thus, etiological diversity in CKD might have a far greater, and more pernicious, influence on BOLD-MRI results than thought by Michaely et al. As the kidney is surrounded by adipose tissue, removal of the out-of-phase subtraction effect caused by this tissue is vital to minimizing fluctuations in T2* values. We, therefore, used in-phase echo time (TE) of the longest possible duration to limit the T2* errors and provide more accurate data, while balancing the signal-to-noise ratio. Michaely et al. used an unusually short TE of just 40ms. We, and other similarly focused groups, understand the limitations of this novel modality and hope that the article does not discourage the application of BOLD-MRI to CKD assessment.

Should the dose of contrast medium be determined solely on the basis of body weight regardless of the patient’s sex?

PurposeThe aim of this study was to evaluate prospectively the difference in contrast enhancement of liver parenchyma between male and female subjects when the total amount of contrast material is determined by the total body weight (TBW).Materials and methodsComputed tomography of the abdomen was performed with a total amount of iodine of 597 ± 3.9 mg I/kg (mean ± SD) over a mean ± SD total injection time of 30 ± 0.26 s. Postcontrast attenuation during the portal venous phase was measured in the liver parenchyma, portal vein, and aorta. These values were summed for each and compared to those obtained before contrast injection. A total of 565 consecutive patients without a history of underlying liver/heart disease, including 297 male and 268 female subjects (age 16–92 years, mean 67 years) were scanned and analyzed using a two-tailed t-test.ResultsThe difference between precontrast and the portal venous phase in the male subjects was 315.4 ± 40.5 HU (mean ± SD), and that in female subjects was 358.6 ± 44.8 HU. This difference was statistically significant (P < 0.0001).ConclusionThe contrast enhancement in females was 13.7% higher than that in males when the amount of iodine administered was based on the TBW. The difference can presumably be attributed to the difference in fat and muscle components. This result suggests that the amount of contrast material used in females should be reduced according to this difference.

Estrogen-producing endometrioid adenocarcinoma resembling sex cord-stromal tumor of the ovary: a review of four postmenopausal cases

AbstractThe 4 present cases with endometrioid adenocarcinoma (EMA) of the ovary were characterized by estrogen overproduction and resemblance to sex cord-stromal tumor (SCST). The patients were all postmenopausal, at ages ranging from 60 to 79 years (av. 67.5), who complained of abdominal discomfort or distention and also atypical genital bleeding. Cytologically, maturation of the cervicovaginal squamous epithelium and active endometrial proliferation were detected. The serum estrogen (estradiol, E2) value was preoperatively found to be elevated, ranging from 48.7 to 83.0 pg/mL (av. 58.4). In contrast, follicle stimulating hormone was suppressed to below the normal value. MR imaging diagnoses included SCSTs such as granulosa cell tumor or thecoma for 3 cases because of predominantly solid growth, and epithelial malignancy for one case because of cystic and solid structure. Grossly, the solid part of 3 cases was homogeneously yellow in color. Histologically, varying amounts of tumor components were arranged in solid nests, hollow tubules, cord-like strands and cribriform-like nests in addition to the conventional EMA histology.In summary, postmenopausal ovarian solid tumors with the estrogenic manifestations tend to be preoperatively diagnosed as SCST. Due to this, in the histological diagnosis, this variant of ovarian EMA may be challenging and misdiagnosed as SCST because of its wide range in morphology.Virtual slideshttp://www.diagnosticpathology.diagnomx.eu/vs/6096841358065394