Anatomical information of the lenticulostriate arteries on high-resolution 3D-TOF MRA at 3 T: comparison with 3D-DSA.

PURPOSE: As the lenticulostriate arteries (LSAs) perfuse neurologically important areas, it is necessary to accurately assess the origin and number of the LSAs before surgery. Although three-dimensional time-of-flight MR angiography (3D-TOF MRA) is a non-invasive procedure, it requires high-resolution (HR) images to depict the LSAs with a small diameter. Therefore, we performed 3D-TOF MRA with the maximum HR (HR-MRA) using a 3 T scanner to examine whether a good depiction of the LSAs, equivalent to that of digital subtraction angiography (DSA), could be obtained. METHODS: Our study group comprised 16 consecutive patients who underwent HR-MRA and 3D-DSA. In both studies, we evaluated the localization of the origin from M1, M2, or A1 segments, their number of stems, and depiction. RESULTS: There was no significant difference in the visualization of the LSAs between HR-MRA and 3D-DSA (P values; M1, M2, and A1 = 0.39, 0.69, and 0.69, respectively), and both the number of stems and the localization of the origin of the LSAs corresponded between the two examinations. CONCLUSION: HR-MRA at 3 T can depict the LSA well. It reveals the number of the LSA stems and the LSA origin comparatively with DSA.

[Bilateral Chronic Subdural Hematomas].

Chronic subdural hematomas(SDHs)do not infrequently present isodensity on CT. They should not be overlooked, particularly if bilateral. Therefore, checking for an abnormal mass effect and visualizing the cortical sulci in higher slices should be routine. In suspected cases, MRI can be a reliable tool for establishing the diagnosis. SDHs or subdural hygromas are often found in patients with intracranial hypotension, along with other findings such as thickened dural enhancement, enlarged dural sinuses, an anterior shift of the brainstem, inferior shift of the cerebellar tonsils, and others. In such cases, some techniques are indicated for visualizing cerebrospinal fluid leakage from the dural sac. Conditions with similar imaging findings, such as chronic SDHs, include dural metastases, several kinds of granulomatous disease, and hypertrophic pachymeningitis. Additionally, it is essential to consider child abuse when SDH is found in children.

[Brain Abscess].

Although the prognosis of brain abscesses has historically improved, the mortality rate still ranges from 5 to 32%, with ventricular perforation reaching 50% and 85-100% in fungal brain abscesses. The characteristic finding of ring-like enhancement by contrast-enhanced imaging is non-specific, and DWI, SWI and MR spectroscopy are very useful in differentiating brain abcesses from necrotizing brain tumors. Brain abscesses show apparent diffusion restriction on the DWI/apparent diffusion coefficient(ADC) map, whereas necrotizing brain tumors often show a weak diffusion restriction. The "dual rim sign" on SWI is also a highly specific finding of brain abscess.

Evaluation of Intradural Ecchordosis Physaliphora With Three-Dimensional Fluid-Attenuated Inversion Recovery.

OBJECTIVE: This study evaluated the efficacy of 3-dimensional fluid-attenuated inversion recovery (3D FLAIR) for detecting intradural ecchordosis physaliphora (EP). METHODS: We retrospectively determined the presence or absence of intradural EP on 3D FLAIR for 3888 consecutive patients, classifying the EP as "classical" or "possible" and analyzing the prevalence, size, and presence or absence of an intraosseous stalk. Where available, magnetic resonance cisternography images were compared with the 3D FLAIR images. RESULTS: Intradural EP was identified in 50 patients (1.3%): 36 (0.9%) classical and 14 (0.4%) possible. The classical EPs were significantly larger than the possible EPs (P < 0.01). Nine EPs (18.0%) showed an osseous stalk. Magnetic resonance cisternography was performed for 19 EPs (16 classical, 3 possible), detecting all 16 classical EPs but none of the possible EPs. CONCLUSIONS: Classical EPs were detected by 3D FLAIR as with magnetic resonance cisternography. The 3D FLAIR findings suggested a new type of possible EP variant previously unreported.

Evaluation of a high-signal lesion posterior to the intracranial vertebral artery using 3D balanced fast-field echo imaging.

Previous reports have identified a small, benign, high-signal lesion (HSL) posterior to the intracranial vertebral artery and associated with the ipsilateral spinal accessory nerve (SAN) using 3D fluid-attenuated inversion recovery (3D FLAIR) imaging as an emerging new entity. To elucidate the relationship between HSLs and SAN, 76 patients with 86 HSLs were evaluated using 3D FLAIR and 3D balanced fast-field echo (3D bFFE imaging). All HSLs showed contact with ipsilateral SAN on both the sequences. 3D bFFE imaging clearly distinguished between the two structures unlike 3D FLAIR. Moreover, SAN was surrounded by HSLs on 3D bFFE images, which may be a characteristic of this entity.

Small high-signal lesions posterior to the intracranial vertebral artery incidentally identified by 3D FLAIR: retrospective study of 127 patients.

PURPOSE: A small, benign high-signal lesion (HSL) posterior to the intracranial vertebral artery (VA) at the foramen magnum is a new entity revealed by a 3D FLAIR sequence. However, this entity has not been sufficiently investigated. We aimed to investigate the MR imaging findings of HSLs posterior to the intracranial VA that were incidentally detected by 3D FLAIR. METHODS: We retrospectively evaluated 3717 patients using a 3-T MR unit. HSLs on 3D FLAIR were assessed for prevalence, size, contact with the spinal accessory nerve (SAN), and size changes on follow-up images. RESULTS: Of 3717 patients, 127 (3.4%) (58 males and 69 females; age, 60.0 ± 18.9 years) showed 142 HSLs posterior to the intracranial VA. In total, 114 patients (89.8%) had a single lesion, whereas 13 patients (10.2%) had multiple lesions. The mean lesion size was 3.8 ± 1.6 mm. All HSLs showed contact with the ipsilateral SAN. Of 69 HSLs that were imaged during follow-up, the size was stable in 91.3% and increased in 8.7%. CONCLUSION: HSLs posterior to the intracranial VA were incidentally detected in 3.4% of patients by 3D FLAIR. Our results indicated a possible association between HSLs and SAN. These lesions appear to be benign in etiology and thus would not require any surgical intervention without continuous growth in a short period or relevant signs and symptoms.

Stereotactic radiosurgery for patients with multiple brain metastases (JLGK0901): a multi-institutional prospective observational study.

BACKGROUND: We aimed to examine whether stereotactic radiosurgery without whole-brain radiotherapy (WBRT) as the initial treatment for patients with five to ten brain metastases is non-inferior to that for patients with two to four brain metastases in terms of overall survival. METHODS: This prospective observational study enrolled patients with one to ten newly diagnosed brain metastases (largest tumour <10 mL in volume and <3 cm in longest diameter; total cumulative volume ≤15 mL) and a Karnofsky performance status score of 70 or higher from 23 facilities in Japan. Standard stereotactic radiosurgery procedures were used in all patients; tumour volumes smaller than 4 mL were irradiated with 22 Gy at the lesion periphery and those that were 4-10 mL with 20 Gy. The primary endpoint was overall survival, for which the non-inferiority margin for the comparison of outcomes in patients with two to four brain metastases with those of patients with five to ten brain metastases was set as the value of the upper 95% CI for a hazard ratio (HR) of 1·30, and all data were analysed by intention to treat. The study was finalised on Dec 31, 2012, for analysis of the primary endpoint; however, monitoring of stereotactic radiosurgery-induced complications and neurocognitive function assessment will continue for the censored subset until the end of 2014. This study is registered with the University Medical Information Network Clinical Trial Registry, number 000001812. FINDINGS: We enrolled 1194 eligible patients between March 1, 2009, and Feb 15, 2012. Median overall survival after stereotactic radiosurgery was 13·9 months [95% CI 12·0-15·6] in the 455 patients with one tumour, 10·8 months [9·4-12·4] in the 531 patients with two to four tumours, and 10·8 months [9·1-12·7] in the 208 patients with five to ten tumours. Overall survival did not differ between the patients with two to four tumours and those with five to ten (HR 0·97, 95% CI 0·81-1·18 [less than non-inferiority margin], p=0·78; pnon-inferiority<0·0001). Stereotactic radiosurgery-induced adverse events occurred in 101 (8%) patients; nine (2%) patients with one tumour had one or more grade 3-4 event compared with 13 (2%) patients with two to four tumours and six (3%) patients with five to ten tumours. The proportion of patients who had one or more treatment-related adverse event of any grade did not differ significantly between the two groups of patients with multiple tumours (50 [9%] patients with two to four tumours vs 18 [9%] with five to ten; p=0·89). Four patients died, mainly of complications relating to stereotactic radiosurgery (two with one tumour and one each in the other two groups). INTERPRETATION: Our results suggest that stereotactic radiosurgery without WBRT in patients with five to ten brain metastases is non-inferior to that in patients with two to four brain metastases. Considering the minimal invasiveness of stereotactic radiosurgery and the fewer side-effects than with WBRT, stereotactic radiosurgery might be a suitable alternative for patients with up to ten brain metastases. FUNDING: Japan Brain Foundation.

Predictive significance of mean apparent diffusion coefficient value for responsiveness of temozolomide-refractory malignant glioma to bevacizumab: preliminary report.

BACKGROUND: Recurrent glioblastoma after initial radiotherapy plus concomitant and adjuvant temozolomide is problematic. Here, patients with temozolomide-refractory high-grade gliomas were treated with bevacizumab (BV) and evaluated using apparent diffusion coefficient (ADC) for response. METHODS: Nine post-temozolomide recurrent or progressive high-grade glioma patients (seven with glioblastoma and two with anaplastic astrocytoma) were treated with BV monotherapy. Average age was 57 years (range, 22-78), median Karnofsky Performance Scale (KPS) was 70 (30-80) and median BV line number was 2 (2-5). Two had additional stereotactic radiotherapy within 6 months prior to BV. Magnetic resonance (MR) imaging after BV therapy was performed within 2 weeks with calculation of mean ADC (mADC) values of enhancing tumor contours. RESULTS: Post-BV treatment MR imaging showed decreased tumor volumes in eight of nine cases (88.9 %). Partial response was obtained in four cases (44.4 %), four cases had stable disease, and one had progressive disease. Of 15 evaluable enhancing lesions, 11 shrank and four did not. Pretreatment mADC values were above 1100 (10(-6) mm(2)/s) in all responding tumors, while all non-responding lesions scored below 1100 (p = 0.001). mADC decreased after the first BV treatment in all lesions except one. KPS improved in four cases (44.4 %). Median progression-free survival and overall survival for those having all lesions with high mADC (>1100) were significantly longer than those with a low mADC (<1100) lesion (p = 0.018 and 0.046, respectively). CONCLUSIONS: Bevacizumab monotherapy is effective in patients with temozolomide-refractory recurrent gliomas and tumor mean ADC value can be a useful marker for prediction of BV response and survival.

Postoperative evaluation of superficial temporal artery-middle cerebral artery bypass using an MR angiography technique with combined white-blood and black-blood sequences.

PURPOSE: To assess the performance of the hybrid of opposite-contrast MR angiography (HOP MRA) technique, which combines flow dephasing and compensating sequences, in the postoperative evaluation of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass. MATERIALS AND METHODS: Both 3D-HOP MRA and 3D-time-of-flight (TOF) MRA at 1.5 Tesla were performed in 19 patients after STA-MCA bypass. The two techniques were visually evaluated to compare the visualization of distal MCA branches and the length and number of depicted recipient MCA branches. Additionally, for the depicted recipient MCA branches, the contrast-to-noise ratio (CNR) and length were compared between the two techniques. RESULTS: The 3D-HOP MRA provided better visualization of the recipient MCA branches than 3D-TOF MRA in 10 of the 19 patients, while the depicted recipient MCA branches were longer on 3D-HOP MRA than on 3D-TOF MRA in 9 patients. Although not statistically significant, the average number of depicted recipient branches by 3D-HOP MRA (2.16) was greater than that by 3D-TOF MRA (1.79). 3D-HOP MRA was significantly superior to 3D-TOF MRA in both CNR (119.0 versus 74.3) and length of the recipient MCA branches (72.0 versus 49.9 pixels). CONCLUSION: 3D-HOP MRA is superior to 3D-TOF MRA for the detailed evaluation of STA-MCA bypass.

Vessel Wall Imaging of Intracranial Arteries: Fundamentals and Clinical Applications.

With the increasing use of 3-tesla MRI scanners and the development of applicable sequences, it has become possible to achieve high-resolution, good contrast imaging, which has enabled the imaging of the walls of small-diameter intracranial arteries. In recent years, the usefulness of vessel wall imaging has been reported for numerous intracranial arterial diseases, such as for the detection of vulnerable plaque in atherosclerosis, diagnosis of cerebral arterial dissection, prediction of the rupture of cerebral aneurysms, and status of moyamoya disease and cerebral vasculitis. In this review, we introduce the histological characteristics of the intracranial artery, discuss intracranial vessel wall imaging methods, and review the findings of vessel wall imaging for various major intracranial arterial diseases.

Imaging of Central Nervous System Parasitic Infections.

Parasitic infections of the central nervous system (CNS) constitute a wide range of diseases, some quite prevalent across the world, some exceedingly rare. Causative parasites can be divided into two groups: unicellular protozoa and multicellular helminthic worms. This includes diseases such as neurotoxoplasmosis and neurocysticercosis, which represent a major cause of pathology among certain populations, and some more uncommon diseases, as primary amebic meningoencephalitis and neuroschistosomiasis. In this review, we focus on imaging manifestation and some helpful clinical and epidemiologic features of such conditions, providing radiologists with helpful information to identify and correctly diagnose the most common of those pathologies.

Magnetic resonance bone imaging: applications to vertebral lesions.

MR bone imaging is a recently introduced technique, that allows visualization of bony structures in good contrast against adjacent structures, like CT. Although CT has long been considered the modality of choice for bone imaging, MR bone imaging allows visualization of the bone without radiation exposure while simultaneously allowing conventional MR images to be obtained. Accordingly, MR bone imaging is expected as a new imaging technique for the diagnosis of miscellaneous spinal diseases. This review presents several sequences used in MR bone imaging including black bone imaging, ultrashort/zero echo time (UTE/ZTE) sequences, and T1-weighted 3D gradient-echo sequence. We also illustrate clinical cases in which spinal lesions could be effectively demonstrated on MR bone imaging, performed in most cases using a 3D gradient-echo sequence at our institution. The lesions presented herein include degenerative diseases, tumors and similar diseases, fractures, infectious diseases, and hemangioma. Finally, we discuss the differences between MR bone imaging and previously reported techniques, and the limitations and future perspectives of MR bone imaging.

Randomized phase III study of high-dose methotrexate and whole-brain radiotherapy with/without temozolomide for newly diagnosed primary CNS lymphoma: JCOG1114C.

BACKGROUND: The goal was to determine whether the addition of temozolomide (TMZ) to the standard treatment of high-dose methotrexate (HD-MTX) and whole-brain radiotherapy (WBRT) for primary central nervous system lymphoma (PCNSL) improves survival. METHODS: An open-label, randomized, phase III trial was conducted in Japan, enrolling immunocompetent patients aged 20-70 years with histologically confirmed, newly diagnosed PCNSL. After administration of HD-MTX, patients were randomly assigned to receive WBRT (30 Gy) ±â€…10 Gy boost (arm A) or WBRT ±â€…boost with concomitant and maintenance TMZ for 2 years (arm B). The primary endpoint was overall survival (OS). RESULTS: Between September 29, 2014 and October 15, 2018, 134 patients were enrolled, of whom 122 were randomly assigned and analyzed. At the planned interim analysis, 2-year OS was 86.8% (95% confidence interval [CI]: 72.5-94.0%) in arm A and 71.4% (56.0-82.2%) in arm B. The hazard ratio was 2.18 (95% CI: 0.95-4.98), with the predicted probability of showing the superiority of arm B at the final analysis estimated to be 1.3%. The study was terminated early due to futility. O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status was measured in 115 tumors, and it was neither prognostic nor predictive of TMZ response. CONCLUSIONS: This study failed to demonstrate the benefit of concomitant and maintenance TMZ in newly diagnosed PCNSL.

Usefulness of black-blood magnetic resonance angiography generated from vessel wall imaging after the stent-assisted treatment of intracranial arterial diseases.

PURPOSE: After stent-assisted treatment for intracranial diseases, three-dimensional time-of-flight magnetic resonance angiography is a noninvasive follow-up method, but susceptibility artifacts prevent accurate evaluations of stented arteries. Sampling perfection with application-optimized contrast using different flip angle evolution (SPACE) sequence often used for vessel wall imaging is less susceptible to susceptibility artifacts, since it is a spin-echo sequence. Hence, we evaluated the feasibility of black-blood magnetic resonance angiography generated from vessel wall imaging data obtained using the SPACE sequence in the depiction of stented arteries by comparing with three-dimensional time-of-flight magnetic resonance angiography and digital subtraction angiography. METHODS: Our study group comprised 11 consecutive patients. For both three-dimensional time-of-flight magnetic resonance angiography and black-blood magnetic resonance angiography, the contrast ratio obtained from the stented artery and the normal artery proximal to the stent were calculated. And the depiction of stented arteries was visually evaluated. Additionally, the relative diameter index obtained from the stented artery and the normal artery proximal to the stent were calculated for three-dimensional time-of-flight magnetic resonance angiography, black-blood magnetic resonance angiography and digital subtraction angiography. RESULTS: The contrast ratio of the stented artery was significantly lower than that of the normal artery on three-dimensional time-of-flight magnetic resonance angiography, but no significant difference was seen using black-blood magnetic resonance angiography. Regarding both the diameter index and the visual assessment score, black-blood magnetic resonance angiography was significantly better than three-dimensional time-of-flight magnetic resonance angiography. On black-blood magnetic resonance angiography, the diameter index was equal to that of digital subtraction angiography, and the flow signal was homogeneous and continuous in most the cases.

Hybrid of opposite-contrast MRA of the brain by combining time-of-flight and black-blood sequences: initial experience in major trunk stenoocclusive diseases.

PURPOSE: To assess the feasibility of a new MR angiography (MRA) technique named hybrid of opposite-contrast MRA (HOP MRA) that combined the time-of-flight (TOF) MRA with a flow-sensitive black-blood (FSBB) sequence in the diagnosis of major trunk stenoocclusive diseases. MATERIALS AND METHODS: On a 1.5 Tesla imager using a dual-echo three-dimensional (3D)-gradient-echo sequence, we obtained the first echo for TOF MRA followed by the second echo for FSBB. We then subtracted the FSBB data set from that of TOF MRA followed by maximum intensity projection. In four normal volunteers and 19 patients with chronic stenoocclusive disease of the major trunk, we performed HOP MRA along with 3D-TOF MRA and compared the findings. RESULTS: In the volunteer group, the HOP MRA technique improved the demonstration of distal arterial branches. In 12 of the 19 patients, the HOP MRA better visualized branches distal to the lesion as well as distal branches of normal trunks than 3D-TOF MRA, while both techniques provided equivalent depiction of branches distal to the lesion but better depiction of normal distal branches in three patients. CONCLUSION: The HOP-MRA technique is promising in major trunk stenoocclusive diseases as it better demonstrates distal branches probably representing collaterals than 3D-TOF MRA.

CT angiography covering both cervical and cerebral arteries using high iodine concentration contrast material with dose reduction on a 16 multidetector-row system.

INTRODUCTION: Our aim was to examine the feasibility of a computed tomographic angiography (CTA) protocol using a reduced dose of high-concentration contrast material on a 16 multidetector-row system to visualize both cervical and cerebral arteries in one session. METHODS: In 31 consecutive patients, we performed CTA covering the cervical and cerebral arteries. The patients were assigned to one of three groups: group A, 100 mL of 300 mgI/mL; group B, 80 mL of 370 mgI/mL; and group C, 60 mL of 370 mgI/mL followed by a 30-mL saline flush. Arterial enhancements were quantified by measuring attenuation values of the common carotid artery, internal jugular vein, proximal middle cerebral artery (MCA), basilar artery, and straight sinus on source images. Visualizations of the carotid bifurcation and arteries continuing to the circle of Willis were rated on a three-point grading scale on CTA images for qualitative assessment. RESULTS: There were no statistically significant differences in attenuation of all the target vessels among the three groups, with the one exception being a lower attenuation of the MCA in group C than in groups A and B (P < 0.01). Neither were there any significant differences noted among the three groups on the visual assessment. CONCLUSION: Use of a reduced dose of high iodine concentration contrast material may provide an equal degree of image quality for CTA covering the craniocervical region on a 16 multidetector-row system.