High-signal venous sinuses on MR angiography: discrimination between reversal of venous flow and arteriovenous shunting using arterial spin labeling.

PURPOSE: It is sometimes difficult to differentiate between high signals originating from a reverse flow on magnetic resonance angiography (MRA) and occult arteriovenous shunting. We attempted to determine whether arterial spin labeling (ASL) can be used to discriminate reversal of venous flow from arteriovenous shunting for high-signal venous sinuses on MR angiography. METHODS: Two radiologists evaluated the signals of the venous sinus on MRA and ASL obtained from 364 cases without arteriovenous shunting. In addition, the findings on MRA were compared with those on ASL in an additional 13 patients who had dural arteriovenous fistula (DAVF). RESULTS: In the 364 cases (728 sides) without arteriovenous shunting, a high signal due to reverse flow in the cavernous sinuses (CS) was observed on 99 sides (13.6%) on MRA and none on ASL. Of these cases, a high signal in the sigmoid sinus, transverse sinus, and internal jugular vein was seen on 3, 3, and 8 sides, respectively. All of these venous sinuses showed a high signal from the reverse flow on MRA images. CONCLUSION: ASL is a simple and useful MR imaging sequence for differentiating between reversal of venous flow and CS DAVF. In the sigmoid and transverse sinus, ASL showed false-positives due to the reverse flow from the jugular vein, which may be a limitation of which radiologists should be aware.

Subarachnoid Hemorrhage Caused by Ruptured Aneurysm of the Artery of Adamkiewicz: a Case Report.

A 66-year-old man presented with a 6-day history of progressive posterior cervical pain that included lower back pain and fever. Neurological examinations revealed neck stiffness. Computed tomography demonstrated convexity subarachnoid hemorrhage. A spinal T2-weighted image revealed a hypointense signal lesion with contrast enhancement of the intradural extramedullary space at Th12-L1. Digital subtraction angiography showed a fusiform aneurysm with a 10 mm diameter in the artery of Adamkiewicz. We diagnosed the patient's condition as a ruptured aneurysm of the artery of Adamkiewicz. By day 41 the aneurysm had disappeared following conservative treatment. Aneurysms arising from the artery of Adamkiewicz are extremely rare and can cause both convexity and spinal subarachnoid hemorrhages. Clinicians should therefore look for spinal lesions if patients with convexity subarachnoid hemorrhage of an unknown origin have lower back pain as their initial symptom.

Hypoglossal Nerve Palsy due to Compression by a Persistent Primitive Hypoglossal Artery: Case Report.

A 51-year-old Japanese woman was admitted to our hospital because of speech difficulty following severe headache. Neurological examination showed dysarthria and tongue weakness on the right side, indicating right hypoglossal nerve palsy. Needle electromyography of the right side of the tongue showed fibrillation potentials. Magnetic resonance angiography and computed tomography angiography revealed a right, persistent, primitive hypoglossal artery (PPHA) that met Lie's diagnostic criteria. Digital subtraction angiography showed an extended PPHA with irregular caliber in the portion running through the right hypoglossal canal. We diagnosed compression neuropathy of the hypoglossal nerve due to PPHA enlargement based on the findings of ipsilateral hypoglossal nerve palsy, fibrillation that indicated peripheral nerve palsy, and the enlarged diameter of the portion of the PPHA running through the right hypoglossal canal. We prescribed antihypertensive therapy. At 1 year after onset, her tongue weakness was alleviated. Clinicians should consider compression neuropathy due to a PPHA as one of the possibilities in the differential diagnosis of hypoglossal nerve palsy.

Thin-slice Two-dimensional T2-weighted Imaging with Deep Learning-based Reconstruction: Improved Lesion Detection in the Brain of Patients with Multiple Sclerosis.

PURPOSE: Brain MRI with high spatial resolution allows for a more detailed delineation of multiple sclerosis (MS) lesions. The recently developed deep learning-based reconstruction (DLR) technique enables image denoising with sharp edges and reduced artifacts, which improves the image quality of thin-slice 2D MRI. We, therefore, assessed the diagnostic value of 1 mm-slice-thickness 2D T2-weighted imaging (T2WI) with DLR (1 mm T2WI with DLR) compared with conventional MRI for identifying MS lesions. METHODS: Conventional MRI (5 mm T2WI, 2D and 3D fluid-attenuated inversion recovery) and 1 mm T2WI with DLR (imaging time: 7 minutes) were performed in 42 MS patients. For lesion detection, two neuroradiologists counted the MS lesions in two reading sessions (conventional MRI interpretation with 5 mm T2WI and MRI interpretations with 1 mm T2WI with DLR). The numbers of lesions per region category (cerebral hemisphere, basal ganglia, brain stem, cerebellar hemisphere) were then compared between the two reading sessions. RESULTS: For the detection of MS lesions by 2 neuroradiologists, the total number of detected MS lesions was significantly higher for MRI interpretation with 1 mm T2WI with DLR than for conventional MRI interpretation with 5 mm T2WI (765 lesions vs. 870 lesions at radiologist A, < 0.05). In particular, of the 33 lesions in the brain stem, radiologist A detected 21 (63.6%) additional lesions by 1 mm T2WI with DLR. CONCLUSION: Using the DLR technique, whole-brain 1 mm T2WI can be performed in about 7 minutes, which is feasible for routine clinical practice. MRI with 1 mm T2WI with DLR enabled increased MS lesion detection, particularly in the brain stem.

Arterial Spin Labeling Was Useful for Evaluating the Treatment Response of a Transverse-Sigmoid Sinus Dural Arteriovenous Fistula: A Case Report.

Objective: We report the case of a patient in whom arterial spin labeling (ASL) was useful for assessing the effects of treatment for a transverse-sigmoid sinus dural arteriovenous fistula (TSS-dAVF). Case Presentation: The patient was a 65-year-old man. Cerebral angiography demonstrated an aggressive dAVF involving the TSS, superior sagittal sinus (SSS), and the sinus confluence, with severe cortical and deep venous reflux. We performed multiple transarterial and transvenous embolizations for the TSS and sinus confluence lesion. The shunt disappeared almost completely after embolization. A high signal intensity that had been apparent in the SSS and straight sinus (StS) on ASL imaging before embolization disappeared after embolization. ASL imaging 3 months after embolization revealed slightly a high signal intensity in the StS, which was considered to be due to recurrence of the lesion. Moreover, recurrence of the confluence and TSS-dAVF was observed on cerebral angiography 6 months after embolization. As additional embolization was considered difficult, radiation therapy was recommended, but the patient refused; therefore, follow-up was performed. As ASL imaging findings were consistent with cerebral angiography findings, careful examination and monitoring of changes on ASL imaging were subsequently performed. Conclusion: Follow-up using ASL imaging is useful to assess the effects of treatment performed for a dAVF.

Arterial Spin Labeling Imaging of a Giant Aneurysm Leading to Subarachnoid Hemorrhage following Cerebral Infarction.

An 83-year-old Japanese man was admitted with dysarthria and right hemiparesis. He had had a large intracranial aneurysm on the left internal carotid artery 5 years before admission and had been followed up under conservative treatment. On admission, diffusion-weighted imaging revealed a hyperintense signal on the left anterior choroidal artery territory. Time-of-flight magnetic resonance angiography demonstrated poor visibility of the middle and anterior cerebral arteries and the inferior giant aneurysm, suggesting distal emboli from aneurysm thrombosis or a reduction of blood outflow due to aneurysm thrombosis. Arterial spin labeling (ASL) signal increased in the giant aneurysm, suggesting blood stagnation within the aneurysmal sac, and decreased in the left hemisphere. We diagnosed cerebral infarction due to aneurysm thrombosis, and started antithrombotic therapy. On day 2, he suddenly died of subarachnoid hemorrhage due to rupturing of the giant aneurysm. When thrombosis occurs in a giant aneurysm, increasing ASL signal within the aneurysm and decreasing ASL signal with poor visibility on magnetic resonance angiography in the same arterial territory may indicate the danger of impending rupture of the giant aneurysm.