Waka Mizukoshi

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.

Anomalous origin of the occipital artery diagnosed by magnetic resonance angiography

IntroductionIt is well known that the occipital artery (OA) can arise from the internal carotid artery (ICA) or vertebral artery (VA). However, the incidence of an anomalously originating OA has not been reported. We investigate its incidence and characteristic features on magnetic resonance angiography (MRA).MethodsWe retrospectively reviewed MRA images of 2,866 patients that included the carotid bifurcation; images were obtained using a standard noncontrast MRA protocol and two 1.5-T MR units.ResultsWe diagnosed six cases (seven arteries) of anomalously originating OA, which represented an incidence of 0.21%. The OA arose from the ICA in four patients (five arteries), from the carotid bifurcation in one, and from the VA in one. Five of the seven arteries occurred on the right.ConclusionAnomalously originating OA is rare and occurs with right-side predominance. Correct diagnosis is necessary before or during cerebral angiography, especially when selective catheterization to the OA is required.

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.

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.

Quantitative assessment of water diffusion changes in brains of children with neurofibromatosis type I using apparent diffusion coefficient.

We measured diffusion changes in the brains of children with neurofibromatosis type 1 (NF1). Using diffusion-weighted and conventional magnetic resonance (MR) images of 42 children with NF1 (19 girls, 23 boys; 7 months-16 years, mean 6.8 years) and 42 age-matched controls (20 boys, 22 girls; 6 months-17 years, mean, 6.9 years), we calculated the apparent diffusion coefficient (ADC) from the automatically generated ADC maps and placed regions of interest in the pons, middle cerebellar and cerebral peduncles, thalami, globus pallidi and frontal white matter. Evaluating only normal-appearing regions on conventional images, we compared mean ADCs using the unpaired Student t test. Means were not significantly different in frontal white matter but were larger in the other regions in the NF1 (P < 0.01). Although conventional MR showed normal intensity, ADCs of the pons, middle cerebellar and cerebral peduncles, thalami and globus pallidi were significantly larger in the NF1.