High-resolution Magnetic Resonance Imaging Findings Research Articles

High-Resolution Magnetic Resonance Imaging in Endovascular Treatment of Vertebrobasilar Junction Stenosis.

Vertebrobasilar junction (VBJ) stenosis is a challenge in endovascular treatment due to structural variants and complexities. The role of high-resolution magnetic resonance imaging (HRMRI) in endovascular treatment for patients with severe VBJ stenosis is uncertain. Four patients with symptomatic VBJ stenosis underwent HRMRI of the vessel wall before endovascular treatment. In 3 patients, the VBJ could not be visualized on luminal imaging. One of them had a hypoplastic artery and 2 of them had severe stenotic arteries on HRMRI. HRMRI showed an artery with a negative remodeling in a patient with a hypoplastic vertebral artery. One patient had intraplaque hemorrhage and calcification, and 2 patients had calcification in VBJ lesions. Endovascular treatment was performed utilizing HRMRI findings to guide the decision-making process. HRMRI provides additional information about the structure and angle of the VBJ, the characteristics and vulnerability of the plaques, and the lesion size, thus helping to improve the operation process and reduce the risk of complications.

HR-MRI findings of intracranial artery stenosis and distribution of atherosclerotic plaques caused by different etiologies.

To investigate the etiology of intracranial artery stenosis and the distribution characteristics of intracranial artery atherosclerotic stenosis using high-resolution magnetic resonance imaging (HR-MRI). A total of 262 patients with intracranial artery stenosis that underwent HR-MRI from November 2019 to December 2020 were retrospectively enrolled. The etiology of intracranial anterior and posterior circulation artery stenosis was analyzed, and the relationship between the location of plaques and the distribution characteristics of plaques and the occurrence of ischemic stroke was summarized. A total of 276 plaques were identified with HR-MRI. There were 101 cases (36.59%) in the middle cerebral artery (MCA), 14 cases (5.07%) in the posterior cerebral artery (PCA), 90 cases (32.62%) in vertebral artery (VA), and 71 cases (25.72%) in the basilar artery (BA). The infarct rate of ventral and superior wall MCA plaques was higher than that of dorsal and inferior wall (63.33% vs 31.25% P = 0.021) (100.00% vs 50% P = 0.022). MCA with plaques throughout the course had the greatest degree of stenosis (P < 0.001). Sphenoid segment (M1) of MCA was most susceptible (85 cases, 84.16%), MCA plaques were most common in the proximal M1 segment (35 cases, 34.65%), and most BA plaques were found in the distal segment (28 cases, 39.44%). PCA plaques were most frequently involved in traffic anterior segment (P1) (7 cases, 50.00%). HR-MRI could provide accurate imaging reference for clinical evaluation of intracranial arterial stenosis and formulation of treatment plans. The intracranial arterial plates mostly appeared in the middle cerebral artery and vertebral artery. Middle cerebral arteries with atherosclerotic plaques are more likely to narrow.

Non-thrombotic ischemic cerebrovascular events related to the use of tyrosine kinase inhibitors in patients with cancer: high-resolution magnetic resonance imaging findings

The targeted cancer therapies that have been introduced in recent years are directed against cancer-specific molecules and signaling pathways, and thus, they have limited nonspecific toxicities. However, major vascular events, including stroke, are common in patients receiving tyrosine kinase inhibitors (TKIs). Inhibition of vascular endothelial growth factor receptor by some TKIs probably explains such events. Moreover, venous and arterial thromboses, atherosclerosis, and bleeding have been reported. Ischemic lesions can also occur due to impaired angiogenesis or endothelial dysfunction. However, the exact mechanisms of arterial stroke in patients with cancer receiving TKIs are unknown. Here, we have report two cases of non-thrombotic ischemic cerebrovascular events related to TKIs and described the high-resolution magnetic resonance imaging findings.

High resolution MRI-based radiomic nomogram in predicting perineural invasion in rectal cancer

BackgroundTo establish and validate a high-resolution magnetic resonance imaging (HRMRI)-based radiomic nomogram for prediction of preoperative perineural invasion (PNI) of rectal cancer (RC).MethodsOur retrospective study included 140 subjects with RC (99 in the training cohort and 41 in the validation cohort) who underwent a preoperative HRMRI scan between December 2016 and December 2019. All subjects underwent radical surgery, and then PNI status was evaluated by a qualified pathologist. A total of 396 radiomic features were extracted from oblique axial T2 weighted images, and optimal features were selected to construct a radiomic signature. A combined nomogram was established by incorporating the radiomic signature, HRMRI findings, and clinical risk factors selected by using multivariable logistic regression.ResultsThe predictive nomogram of PNI included a radiomic signature, and MRI-reported tumor stage (mT-stage). Clinical risk factors failed to increase the predictive value. Favorable discrimination was achieved between PNI-positive and PNI-negative groups using the radiomic nomogram. The area under the curve (AUC) was 0.81 (95% confidence interval [CI], 0.71–0.91) in the training cohort and 0.75 (95% CI, 0.58–0.92) in the validation cohort. Moreover, our result highlighted that the radiomic nomogram was clinically beneficial, as evidenced by a decision curve analysis.ConclusionsHRMRI-based radiomic nomogram could be helpful in the prediction of preoperative PNI in RC patients.

Association of lateral rectus muscle volume and ocular motility with the abducens nerve in Duane's retraction syndrome.

To investigate the relationship between ocular motility and lateral rectus (LR) muscle volume according to the presence or absence of the abducens nerve in patients with Duane's retraction syndrome (DRS) using high-resolution magnetic resonance imaging (MRI). A total of 54 unilateral DRS patients were divided into two groups according to high-resolution MRI findings: DRS without an abducens nerve on the affected side (absent CN6 group, n = 45) and DRS with symmetric abducens nerves on both sides (present CN6 group, n = 9). Ocular motility was measured by image analysis based on nine gaze photographs. LR volume was measured on T2-weighted coronal MRI of the orbit, and the ratio of paretic/normal side (P/N) LR volume was investigated. Association of the abducens nerve with various parameters including ocular motility, LR volume, and ratios of P/N LR volume were determined. LR volume was smaller in the affected eye than the non-affected eye in both groups. In the present CN6 group, abducens nerve diameter and the ratio of P/N LR volume showed a positive correlation. A smaller LR volume and more limitation of abduction in the affected eye were predictive of an absent abducens nerve in DRS. LR muscle hypoplasia was apparent in the affected eye of DRS patients. Abducens nerve diameter positively correlated with the ratio of P/N LR volume in the present CN6 group. Graphical abstract.

High-resolution magnetic resonance imaging for the follow-up of intracranial arterial dissections.

High-resolution magnetic resonance imaging (HRMRI) with a 3-T system can be utilized to identify intracranial arterial dissections (ICADs) as it reveals more than three key features with better clarity than other conventional imaging modalities. This study aimed to assess the changes in the key features of ICADs on HRMRI over time. We screened patients who had undergone HRMRI within 7days of symptom onset for the evaluation of characteristics associated with intracranial steno-occlusive lesions. Among them, patients who (1) were diagnosed with ICAD based on HRMRI findings and (2) underwent follow-up HRMRI 3-12months after the initial HRMRI were included in the final study. Baseline HRMRI revealed an intramural hematoma, a flap, and a double lumen in 17 (100%), 15 (88%), and 10 (59%) individuals, respectively. At the 3-months follow-up, an intramural hematoma was still observed in two patients; however, there were various changes in the double lumen and intimal flap. At the 6-months follow-up, an intramural hematoma was not observed in most patients, whereas the double lumen and intimal flap persisted in most patients. The 9-months follow-up displayed distinct differences from the initial status, whereas the 12-months follow-up exhibited no intramural hematomas, intimal flaps, or double lumens in most patients. In those with ICAD, radiological changes were observed between the initial HRMRI and subsequent HRMRI. Moreover, typical ICAD features were hardly retained at the 1-year follow-up. These changes might reflect dynamic processes, including the healing state of the patients.

Value of High-resolution MRI in Detecting Lymph Node Calcifications in Patients with Rectal Cancer

To analyze CT and high-resolution MRI findings of nodal metastasis calcifications and determine the value of high-resolution MRI in detecting nodal calcifications in rectal cancer patients. In total, 229 rectal cancer patients were included. The CT was reviewed for the presence of nodal calcifications by two radiologists. High-resolution two-dimensional turbo spin-echo T2-weighted imaging (2D-TSE-T2WI) and fat-suppressed gadolinium-enhanced isotropic high-resolution three-dimensional gradient-echo T1-weighted imaging (3D-GRE-T1WI) were independently reviewed for nodal calcifications by the two radiologists at one-month and two-month intervals, respectively. The sensitivities, specificities and accuracies of the two high-resolution MRI in detecting nodal calcifications were calculated using CT results as a reference. Regional calcified metastatic lymph nodes were found in 28 patients. The node-to-node evaluation revealed that 55 (98.2%) of the 56 calcified lymph nodes were metastatic. Fifty-one (92.7%) calcified metastatic lymph nodes displayed scattered fine punctate calcifications to different degrees on CT. In both types of high-resolution MRI, the calcifications demonstrated a patchy area of markedly reduced signal intensity in corresponding areas that were larger than those on CT. The sensitivity and accuracy of fat-suppressed gadolinium-enhanced isotropic high-resolution 3D-GRE-T1WI were significantly higher than those of high-resolution 2D-TSE-T2WI (76.8% vs 58.9%, P = 0.013; 98.3% vs 97.9%, P = 0.007; respectively). Metastatic nodal calcifications are characteristic imaging findings in rectal cancer. Calcifications are indicated by markedly reduced signal on high-resolution MRI, which will alert radiologists to scrutinize CT for nodal calcifications and aid in the accurate diagnosis of metastatic lymph nodes.

In vivo quantification of mandibular bone remodeling and vascular changes in a Wistar rat model: A novel HR-MRI and micro-CT fusion technique.

PurposeThis study was performed to introduce an in vivo hybrid multimodality technique involving the coregistration of micro-computed tomography (micro-CT) and high-resolution magnetic resonance imaging (HR-MRI) to concomitantly visualize and quantify mineralization and vascularization at follow-up in a rat model.Materials and MethodsThree adult female rats were randomly assigned as test subjects, with 1 rat serving as a control subject. For 20 weeks, the test rats received a weekly intravenous injection of 30 µg/kg zoledronic acid, and the control rat was administered a similar dose of normal saline. Bilateral extraction of the lower first and second molars was performed after 10 weeks. All rats were scanned once every 4 weeks with both micro-CT and HR-MRI. Micro-CT and HR-MRI images were registered and fused in the same 3-dimensional region to quantify blood flow velocity and trabecular bone thickness at T0 (baseline), T4 (4 weeks), T8 (8 weeks), T12 (12 weeks), T16 (16 weeks), and T20 (20 weeks). Histological assessment was the gold standard with which the findings were compared.ResultsThe histomorphometric images at T20 aligned with the HR-MRI findings, with both test and control rats demonstrating reduced trabecular bone vasculature and blood vessel density. The micro-CT findings were also consistent with the histomorphometric changes, which revealed that the test rats had thicker trabecular bone and smaller marrow spaces than the control rat.ConclusionThe combination of micro-CT and HR-MRI may be considered a powerful non-invasive novel technique for the longitudinal quantification of localized mineralization and vascularization.

Quantitative analysis of structure–function relationship between ocular motility and superior oblique muscle hypoplasia in unilateral superior oblique palsy

AimsTo determine the structure–function relationship between the degree of superior oblique (SO) hypoplasia and ocular motility in unilateral SO palsy.MethodsA total of 166 patients with unilateral SO palsy were divided...

Spontaneous intracranial vertebral artery dissection with acute ischemic stroke: High-resolution magnetic resonance imaging findings.

Background Acute ischemic stroke (AIS) more frequently develops in patients with intracranial vertebral artery dissection (VAD) than extracranial VAD, and is associated with possible poor clinical outcomes. The aim of this study is to compare high-resolution magnetic resonance imaging (HR-MRI) findings and clinical features of VAD with and without AIS. Methods Twenty-nine lesions from 27 patients (15 male and 12 female patients; age range = 28-73 years) who underwent diffusion MRI and 3T HR-MRI within seven days were included. We classified VAD according to the presence of AIS lesions on diffusion MRI. Clinical features and HR-MRI findings (angiographic patterns, presence of double lumen sign, dissecting flap, posterior inferior cerebellar artery involvement, remodeling index, length of affected vessels, T1-signal intensity, area of intramural hematoma, and grades and patterns of vessel wall enhancement) were evaluated. Results Thirteen VADs with AIS and 16 without AIS were included. There were no significant differences in the clinical parameters (sex, age, risk factors, symptoms). More VADs with AIS presented as a steno-occlusive pattern than VADs without AIS. More VADs without AIS presented with aneurysmal dilation, larger mean remodeling index and longer mean length than VADs with AIS. Presence of intramural hematoma, T1-iso-signal intensity of intramural hematoma and contrast enhancement were significantly more common in VADs with AIS than without AIS. Conclusions Our study showed some differences in HR-MRI comparing intracranial VAD patients with and without AIS. Differing findings may facilitate a better understanding of intracranial VAD and risk assessment of AIS in these patients.

Abstract 57: Arterial Dissection as a Cause of Intracranial Stenosis in East Asians: A High-resolution Magnetic Resonance Imaging Study of 558 Patients

Background: Intracranial occlusive disease is a common cause of stroke worldwide, and is more prevalent in Asians. We hypothesized that non-traumatic intracranial artery dissection (ICAD) may be a common hidden cause of large intracranial occlusive disease in Asian patients with ischemic stroke, and that many patients with ICAD may be misclassified as having intracranial atherosclerotic stenosis (ICAS). Methods: We prospectively recruited patients with acute symptomatic infarcts due to intracranial occlusive disease between January 2011 and October 2016. High-resolution magnetic resonance imaging (HR-MRI) was performed when vascular studies yielded ambiguous results for the diagnosis of ICAS, ICAD, or other causes. Clinical, laboratory, and HR-MRI findings were compared between the ICAS and ICAD groups. Results: Among 937 patients who showed intracranial stenosis on time-of-flight magnetic resonance angiography, HR-MRI was performed in 558. According to HR-MRI features, 123 were classified as ICAD and 252 as ICAS. Male sex, older age, hypertension, and diabetes were more frequent in the HR-confirmed ICAS group. Anterior circulation location, and the presence of vascular calcification and tandem stenosis were also more common in the ICAS group. However, clinical and radiological characteristics did not differ between patients with typical luminal changes of ICAD (n=69) and those with ICAD documented by HR-MRI but no typical luminal changes (n=123). Conclusion: Almost two thirds of ICAD patients in an Asian population were misclassified as having ICAS by standard luminal imaging techniques. Considering the different therapeutic and prognostic approaches in ICAD and ICAS, HR-MRI may be a useful diagnostic tool in this population.

The association between the ring finger protein 213 gene R4810K variant and intracranial major artery stenosis/occlusion in the Han Chinese population and high-resolution magnetic resonance imaging findings

BACKGROUND AND PURPOSE:The ring finger protein 213 (RNF213) gene R4810K variant, a susceptibility locus for moyamoya disease (MMD), has recently been identified to be associated with intracranial major artery stenosis/occlusion (ICASO) without satisfying the diagnostic criteria of MMD in the Japanese population. However, further studies are needed to determine whether this variant is associated with ICASO in other populations and whether R4810K variant-related ICASO could be categorized as MMD. The aim of this study is to elucidate whether the R4810K variant was associated with ICASO among the Han Chinese population and potential histopathology of R4810K variant-related ICASO.MATERIALS AND METHODS:We conducted a case–control study to evaluate association and performed high-resolution (HR) magnetic resonance imaging (MRI) to investigate arterial wall feature of ICASO. The R4810K variant was genotyped in 114 ICASO patients and 268 controls. Then, patients with R4810K variant-related ICASO were subjected to HR MRI examination and presumptively diagnosed based on the characteristics thus observed.STATISTICAL ANALYSIS:The relationship between R4810K variant and ICASO was evaluated by Fisher's exact test with odds ratios (OR) and 95% confidence interval (CI).RESULTS:The R4810K variant was associated with ICASO and increased the risk for ICASO (P < 0.01; OR: 20.2; 95% CI: 2.5–163.11). Presumptive MMD was diagnosed in all female patients with R4810K variant. However, presumptive intracranial atherosclerotic stenosis was diagnosed in one of three males harboring this variant.CONCLUSIONS:The R4810K variant is a genetic risk factor for ICASO among the Han Chinese population and that R4810K variant-related ICASO should be identified as MMD in female but not uncertain in male patients.

Correlation of high-resolution magnetic resonance imaging with surgico-pathological findings in rectal carcinoma patients

Background: Colorectal cancer is the third most common cancer in men, and it is second most common in women worldwide. Magnetic resonance imaging (MRI) is free of ionizing radiation and imparts highest soft tissue contrast; therefore, it can provide the best assessment of evaluation of local spread. The available data show that only a few studies have been done describing the role of high-resolution MRI (HRMRI) in staging of rectal cancer in Indian population. Objectives: The present study attempts to find the correlation and level of agreement between HRMRI and Surgico-pathological findings in rectal carcinoma patients. Materials and Methods: This hospital-based prospective study was conducted on patients diagnosed with rectal cancer. MR study for pre-operative evaluation was done on 97 patients. 60 operated cases who gave the consent were included in the final study. Findings from MR study were compared with surgical and histopathological findings. Results: Result showed that mean tumor size was 7.43 ± 3.12, 6.88 ± 3.04, and 5.67 ± 2.50 by MRI, surgical, and histological methods (P < 0.001). Overall agreement between MRI and operative finding and histopathological finding was 0.95 and 0.75 respectively (P < 0.001), showing good absolute agreement between the methods. Conclusions: There was good agreement between the MR, surgical, and histopathological findings for local staging and pre-operative planning of rectal carcinoma.

Abstract WMP71: Moyamoya-atherosclerosis Syndrome: Clinical and High-resolution Magnetic Resonance Imaging Features

Introduction: The diagnosis in the patients with angiographic moyamoya findings and atherogenic risk factors is challenging. In this study, we try to incorporate high-resolution magnetic resonance imaging (HRMRI) into the diagnostic process of intracranial atherosclerosis associated moyamoya syndrome. Methods: From March 2013 to March 2014, HRMRI was consecutively performed on adult patients with angiographic moyamoya. The patients were classified as moyamoya - plaques (MMD-P) if a plaque could be identified or as moyamoya - no plaques (MMD-NP) if a plaque could not be identified. The angiography, HRMRI findings and atherogenic risk factors of these patients were analyzed. Results: Fifty-one patients (mean age 39±9, 20 males) were enrolled. On traditional angiography, probable intracranial atherosclerosis was identified in 5 patients, no definite diagnosis in 12 patients, and moyamoya disease in 34 patients. On HRMRI, 15 out of 32 patients with risk factors and 4 out of 19 patients without risk factors were found to have plaques and were diagnosed as MMD-P, while the other 32 patients were diagnosed as MMD-NP. The MMD-P patients were more likely to be older and male and were less likely to have cerebral hemorrhage and a history of disease progression. Conclusions: Our study suggests that HRMRI can help diagnose intracranial atherosclerosis more accurately in moyamoya disease patients with atherogenic risk factors. The distinct clinical features between MMD-P and MMD-NP patients suggest different underlying pathophysiology and therefore potentially different treatment strategies.

Spontaneous and Unruptured Chronic Intracranial Artery Dissection : High-resolution Magnetic Resonance Imaging Findings.

The aim of this article is to present high-resolution magnetic resonance imaging (HR-MRI) findings of chronic stage spontaneous and unruptured intracranial artery dissection (ICAD). From March 2012 to April 2016 a total of 29 patients (15 male and14 female, age range 37-68 years) with chronic stage spontaneous and unruptured ICAD (vertebral artery 27, posterior inferior cerebellar artery 1 and middle cerebral artery 1) were retrospectively enrolled. Patients underwent HR-MRI more than 2months (median interval 564 days, range 69-391 days) after symptom onset and were diagnosed at symptom onset or at the first imaging acquisition, which included luminal angiography and/or HR-MRI with clinical information. The HR-MRI findings were evaluated against those of luminal angiography on the basis of the lumen wall morphology, including thickening, contrast enhancement and residual dissection. The HR-MRI findings were classified into complete normalization (normal lumen and wall with or without mild enhancement, n= 6), complete normalization with minimal wall changes (focal wall thickening with enhancement but normal luminal angiography, n= 8), incomplete normalization (focal wall thickening with enhancement with dilatation and stenosis on luminal angiography, n= 4), dissecting aneurysm (fusiform aneurysm with residual dissection findings, n= 8) and occlusion (small outer arterial diameter with diffuse contrast enhancement, n= 3). The use of HR-MRI can demonstrate the distinguishing morphological features of chronic stage of spontaneous and unruptured ICAD as complete normalization, complete normalization with minimal wall changes, incomplete normalization, dissecting aneurysm and occlusion.

More Precise Imaging Analysis and Diagnosis of Moyamoya Disease and Moyamoya Syndrome Using High-Resolution Magnetic Resonance Imaging

The diagnosis of moyamoya disease (MMD) is often uncertain. Moyamoya syndrome (MMS) is often misdiagnosed as MMD. High-resolution magnetic resonance imaging (HR-MRI) enables vessel wall assessment to obtain more precise diagnoses. The aim of this study was to determine the true etiologies of arterial steno-occlusion in patients with an angiographic diagnosis of MMD or MMS using HR-MRI. HR-MRI was performed in 21 adult patients with angiographically proven MMD or MMS. A definite diagnosis was based on the HR-MRI findings. The diagnoses made via the 2 different imaging technologies were compared, and significant findings were analyzed. A total of 21 patients were enrolled, including 7 patients with angiographically proven MMD and 14 patients with angiographically proven MMS. Among the 7 patients with MMD, HR-MRI confirmed the diagnosis of MMD in 6; the remaining patient was considered to have atherosclerosis in the bilateral distal internal carotid arteries (ICAs) and the left middle cerebral artery. Among the 14 patients with MMS, HR-MRI confirmed MMD in 6 patients (including 2 patients with unilateral MMD), atherosclerosis in 5 patients (including 3 patients with bilateral atherosclerosis and 2 with unilateral atherosclerosis), arterial dissection of the left ICA in 1 patient, and MMD in the left cerebral hemisphere with atherosclerosis in the right hemisphere in 2 patients. Differentiating MMD from MMS is difficult in certain situations, and HR-MRI may help provide a more in-depth understanding of MMD and MMS, thereby achieving a more reliable diagnosis.

Adult moyamoya-atherosclerosis syndrome: Clinical and vessel wall imaging features

IntroductionWe sought to incorporate high-resolution magnetic resonance imaging (HRMRI) into the diagnostic process of intracranial atherosclerosis associated moyamoya syndrome in adult patients. MethodsFrom March 2013 to March 2014, HRMRI was consecutively performed on adult patients with angiographic moyamoya. The patients were classified as moyamoya - plaques (MMD-P) if a plaque could be identified or as moyamoya - no plaques (MMD-NP) if a plaque could not be identified. The angiography, HRMRI findings and atherogenic risk factors of these patients were analyzed. ResultsFifty-one patients (mean age 39±9, 20 males) were enrolled. On traditional angiography, probable intracranial atherosclerosis was identified in 5 patients, no definite diagnosis in 12 patients, and moyamoya disease in 34 patients. On HRMRI, 15 out of 32 patients with risk factors and 4 out of 19 patients without risk factors were found to have plaques and were diagnosed as MMD-P, while the other 32 patients were diagnosed as MMD-NP. The MMD-P patients were more likely to be older (P=0.033) and male (P=0.0353) and were less likely to have cerebral hemorrhage (P=0.0066) and a history of disease progression (P=0.0012). ConclusionsOur study suggests that HRMRI can help diagnose intracranial atherosclerosis more accurately in moyamoya disease patients with atherogenic risk factors. The distinct clinical features between MMD-P and MMD-NP patients suggest different underlying pathophysiology and therefore potentially different treatment strategies.

308 High-Resolution Magnetic Resonance Imaging Findings Following Trigeminal Rhizotomy

INTRODUCTION:Patients with trigeminal neuralgia often undergo glycerol or radiofrequency-thermocoagulation glycerol rhizotomy of the trigeminal nerve for treatment of symptoms. To date, radiological changes in patients with trigeminal neuralgia postrhizotomy have not been described. The aim of this

High-Resolution MRI Findings following Trigeminal Rhizotomy.

Patients with trigeminal neuralgia often undergo trigeminal rhizotomy via radiofrequency thermocoagulation or glycerol injection for treatment of symptoms. To date, radiologic changes in patients with trigeminal neuralgia post-rhizotomy have not been described, to our knowledge. The aim of this study was to evaluate patients after trigeminal rhizotomy to characterize post-rhizotomy changes on 3D high-resolution MR imaging. A retrospective review of trigeminal neuralgia protocol studies was performed in 26 patients after rhizotomy compared with 54 treatment-naïve subjects with trigeminal neuralgia. Examinations were reviewed independently by 2 neuroradiologists blinded to the side of symptoms and treatment history. The symmetry of Meckel's cave on constructive interference in steady-state and the presence of contrast enhancement within the trigeminal nerves on volumetric interpolated breath-hold examination images were assessed subjectively. The signal intensity of Meckel's cave was measured on coronal noncontrast constructive interference in steady-state imaging on each side. Post-rhizotomy changes included subjective clumping of nerve roots and/or decreased constructive interference in steady-state signal intensity within Meckel's cave, which was identified in 17/26 (65%) patients after rhizotomy and 3/54 (6%) treatment-naïve patients (P < .001). Constructive interference in steady-state signal intensity within Meckel's cave was, on average, 13% lower on the side of the rhizotomy in patients posttreatment compared with a 1% difference in controls (P < .001). Small regions of temporal encephalomalacia were noted in 8/26 (31%) patients after rhizotomy and 0/54 (0%) treatment-naïve patients (P < .001). Post-trigeminal rhizotomy findings frequently include nerve clumping and decreased constructive interference in steady-state signal intensity in Meckel's cave. Small areas of temporal lobe encephalomalacia are encountered less frequently.

Non-moyamoya vessel network formation along steno-occlusive middle cerebral artery.

In this study, we sought to examine the prevalence and clinical relevance of deep tiny flow voids (DTFV) in patients with steno-occlusive middle cerebral artery (MCA) disease on high-resolution MRI (HRMRI). We retrospectively reviewed the HRMRI and clinical data of 477 patients with MCA steno-occlusive disease. The presence and distribution of DTFV, defined as 3 or more flow voids along the affected MCA on at least 2 consecutive T2-weighted image slices on HRMRI, were observed. The relationships among DTFV, the degree of stenosis (mild <50%, moderate 50%-70%, severe 70%-99%, and occlusion), and infarctions were analyzed. To clarify the difference between DTFV and moyamoya collaterals, we compared the HRMRI findings of the patients with DTFV and 102 patients with moyamoya disease. The prevalence of DTFV was 1.4% in mild stenosis, 12.8% in moderate stenosis, 40.6% in severe stenosis, and 50.7% in MCA occlusions. Of the 112 patients with DTFV, 57 (50.9%) had all 4 quadrants (superior, inferior, dorsal, and ventral sides) of the MCA involved. DTFV were more common in asymptomatic patients than in symptomatic patients with severe stenosis (49.3% vs 30.9%, p = 0.025) and occlusions (68.0% vs 41.7%, p = 0.033). Obvious flow voids in the basal ganglia region were observed in 58 patients (56.9%) with moyamoya disease but in none of the patients with DTFV (p < 0.001). DTFV are common in patients with severe steno-occlusive MCA disease, especially in asymptomatic patients. We hypothesize that DTFV originate from new vessel network formation in response to chronic cerebral ischemia.