Benefits of Photon-Counting CT Myelography for Localization of Dural Tears in Spontaneous Intracranial Hypotension.

Photon-counting CT is an increasingly used technology with numerous advantages over conventional energy-integrating detector CT. These include superior spatial resolution, high temporal resolution, and inherent spectral imaging capabilities. Recently, photon-counting CT myelography was described as an effective technique for the detection of CSF-venous fistulas, a common cause of spontaneous intracranial hypotension. It is likely that photon-counting CT myelography will also have advantages for the localization of dural tears, a separate type of spontaneous spinal CSF leak that requires different myelographic techniques for accurate localization. To our knowledge, prior studies on photon-counting CT myelography have been limited to techniques for detecting CSF-venous fistulas. In this technical report, we describe our technique and early experience with photon-counting CT myelography for the localization of dural tears.

Safety and histopathologic yield of percutaneous CT-guided biopsies of the skull base, orbit, and calvarium.

PURPOSE: Although CT-guided biopsies of the calvarium, skull base, and orbit are commonly performed, the best approaches, efficacy, and safety of such procedures remain scantly described in the literature. This retrospective review of percutaneous biopsies illustrates several approaches to challenging biopsy targets and provides a review of procedural planning considerations and histopathologic yield. METHODS: A retrospective review of CT-guided biopsies of the skull base, calvarium, and orbit between 1/1/2010 and 10/30/2020 was conducted. Patient demographics and procedural factors were recorded, including lesion size and location, biopsy approach, and needle gauge. Outcomes were also noted, including CT dose length product, complications, and histopathologic yield. RESULTS: Sixty-one CT-guided biopsies were included in the final analysis: 34 skull base, 23 calvarial, and 4 orbital lesions. The initial diagnostic yield was 32/34 (94%) for skull base lesions, with one false-negative and one non-diagnostic sample. Twenty-one of twenty-three (91%) biopsies in the calvarium were initially diagnostic, with one false-negative and one non-diagnostic sample. In the orbit, 4/4 biopsies were diagnostic. The total complication rate for the cohort was 4/61 (6.6%). Three complications were reported in skull base procedures (2 immediate and 1 delayed). A single complication was reported in a calvarial biopsy, and no complications were reported in orbital biopsies. CONCLUSION: Percutaneous CT-guided core needle biopsies can be performed safely and with a high diagnostic yield for lesions in the skull base, calvarium, and orbit.

Incremental diagnostic yield and clinical outcomes of lateral decubitus CT myelogram immediately following negative lateral decubitus digital subtraction myelogram.

INTRODUCTION: Spontaneous intracranial hypotension (SIH) caused by a spinal cerebrospinal fluid (CSF) leak classically presents with orthostatic headache. Digital subtraction myelography (DSM) has a well-established diagnostic yield in the absence of extradural spinal collection. At our institution, DSM is followed by lateral decubitus CT myelogram (LDCTM) in the same decubitus position to increase diagnostic yield of the combined study. We evaluated the incremental diagnostic yield of LDCTM following negative DSM and reviewed patient outcomes. METHODS: Retrospective review of consecutive DSMs with subsequent LDCTM from April 2019 to March 2021 was performed. Combined reports were reviewed, and studies with positive DSMs were excluded. Of the exams with negative DSM, only studies with LDCTM reports identifying potential leak site were included. Interventions and follow-up clinical notes were reviewed to assess symptoms improvement following treatment. RESULTS: Of the 83 patients with negative DSMs, 11 (13.2%) had positive leak findings on LDCTMs, and 21 (25.3%) were equivocal. Of 11 positive LDCTMs, 6 leaks were nerve sheath tears (NSTs) and 5 were CSF-venous fistulas (CVFs). 10/11 (90.9%) had intervention and follow-up, with 9/10 (90%) having positive clinical outcome. Of the 21 equivocal LDCTM patients (19 CVFs and 2 NSTs), 15 (71.4%) had interventions and follow-up, with 3/15 (20.0%) with positive clinical outcomes. CONCLUSION: LDCTM following negative DSM has an incremental diagnostic yield up to 38.6%, with up to 14.5% of positive patient outcomes following treatment. LDCTM should be considered after DSM to maximize diagnostic yield of the combined exam.

Spontaneous intracranial hypotension: updates from diagnosis to treatment.

Spontaneous intracranial hypotension (SIH) is caused by spinal cerebrospinal fluid (CSF) leaks, which result in continued loss of CSF volume and multiple debilitating clinical manifestations. The estimated annual incidence of SIH is 5/100,000. Diagnostic methods have evolved in recent years due to improved understanding of pathophysiology and implementation of advanced myelographic techniques. Here, we synthesize recent updates and contextualize them in an algorithm for diagnosis and treatment of SIH, highlighting basic principles and points of practice variability or continued debate. This discussion includes finer points of SIH diagnosis, CSF leak classification systems, less common types and variants of CSF leaks, brain MRI Bern scoring, potential SIH complications, key technical considerations, and positioning strategies for different types of dynamic myelography. The roles of conservative measures, non-targeted or targeted blood patches, surgery, and recently developed endovascular techniques are presented.

Lateral Decubitus Dynamic CT Myelography with Real-Time Bolus Tracking (dCTM-BT) for Evaluation of CSF-Venous Fistulas: Diagnostic Yield Stratified by Brain Imaging Findings.

BACKGROUND AND PURPOSE: CSF-venous fistulas (CVFs) associated with spontaneous intracranial hypotension (SIH) may have a transient appearance, relative to contrast arrival, which may influence the diagnostic performance of lateral decubitus CT myelography (CTM). We developed a dynamic CTM protocol using real-time bolus-tracking (dCTM-BT) to improve the temporal resolution and standardize the timing of CTM acquisitions post-intrathecal contrast administration. The purpose of our study was to evaluate the feasibility of the dCTM-BT technique and evaluate its diagnostic yield for CVF detection, stratified by brain MRI SIH findings. MATERIALS AND METHODS: Patients with suspected SIH without extradural fluid collection on spine MRI who underwent dCTM-BT were retrospectively reviewed. CT bolus monitoring was performed at the upper thoracic level. Following the visualization of dense intrathecal contrast, at least 3 CTM acquisitions of the spine were obtained and reviewed by 2 neuroradiologists. The Bern SIH score was calculated on the brain MRI. The diagnostic yield for CVF detection was evaluated, stratified by Bern score categories and a receiver operating characteristic (ROC) analysis. RESULTS: Out of 48 patients, 23 (48%) had a CVF on dCTM-BT, located at T1-5 (n = 4), T6-12 (n = 18), L1 (n = 1), with 70% on the right. CVF was identified in 22/22 (100%) of patients who had a high Bern score, 1/7 (14%) of those who had an intermediate score, and 0/19 (0%) of those who had a low score. The area under the ROC curve was 0.99 (95% CI, 0.98-1.00). The optimal cutoff was a Bern score of ≥5 (96% sensitivity, 100% specificity). CONCLUSIONS: dCTM-BT is feasible and has excellent diagnostic performance for CVF identification/localization. The Bern score is strongly associated with CVF detection and may help inform who will benefit from dCTM-BT.

Vessel wall imaging features of Moyamoya disease in a North American population: patterns of negative remodelling, contrast enhancement, wall thickening, and stenosis.

BACKGROUND: This study characterized vessel wall imaging (VWI) features of Moyamoya disease (MMD) in a predominantly adult population at a North American center. METHODS: Consecutive patients with VWI were included. Twelve arterial segments were analyzed for wall thickening, degree and pattern of contrast enhancement, and remodeling. RESULTS: Overall, 286 segments were evaluated in 24 patients (mean age = 36.0 years [range = 1-58]). Of 172 affected segments, 163 (95%) demonstrated negative remodeling. Complete vessel wall obliteration was most frequent in the proximal M1 (17/48, 35%). Affected segments enhanced in 72/172 (42%) (n = 15 for grade II; n = 54 for concentric and n = 18 for eccentric); 20 of 24 (83%) patients had at least one enhancing segment. Both enhancing and non-enhancing segments were present in 19/20 (95%) patients. Vessel wall enhancement was most common in the proximal segments and correlated to the degree of stenosis (p < 0.001), and outer wall diameter (p < 0.001), but not disease duration (p = 0.922) or Suzuki score (p = 0.477). Wall thickening was present in 82/172 (48%) affected segments and was associated with contrast enhancement (p < 0.001), degree of stenosis (p < 0.001), and smaller outer wall diameter (p = 0.004). CONCLUSION: This study presents VWI findings in North American patients with MMD. Negative remodeling was the most common finding. Most patients had both enhancing and non-enhancing abnormal segments. Vessel wall enhancement was most common in proximal segments, variable in pattern or degree and was correlated to the degree of stenosis and smaller outer wall diameter.

Lateral decubitus dynamic CT myelography for fast cerebrospinal fluid leak localization.

Dynamic CT myelography is used to precisely localize fast spinal CSF leaks. The procedure is most commonly performed in the prone position, which successfully localizes most fast ventral leaks. We have recently encountered a small subset of patients in whom prone dynamic CT myelography is unsuccessful in localizing leaks. We sought to determine the added value of lateral decubitus dynamic CT myelography, which is occasionally attempted in our practice, in localizing the leak after failed prone dynamic CT myelography. We retrospectively identified 6 patients who underwent lateral decubitus dynamic CT myelography, which was performed in each case because their prone dynamic CT myelogram was unrevealing. Two neuroradiologists independently reviewed preprocedural spine MRI and all dynamic CT myelograms for each patient. Lateral decubitus positioning allowed for precise leak localization in all 6 patients. Five of six patients were noted to have dorsal and/or lateral epidural fluid collections on spine MRI. One patient had a single prominent diverticulum on spine MRI (larger than 6 mm), whereas the others had no prominent diverticula. Our study suggests that institutions performing dynamic CT myelography to localize fast leaks should consider a lateral decubitus study if performing the study in the prone position is unrevealing. Furthermore, the presence of dorsal and/or lateral epidural fluid collections on spine MRI may suggest that a lateral decubitus study is of higher yield and could be considered initially.

Osseous spicules of the posterior elements causing fast cerebrospinal fluid leaks.

PURPOSE: Dural tears are a common cause of spontaneous spinal CSF leaks. The majority of such leaks occur ventrally along the thecal sac, typically due to ventral osseous spicules that cause a rent in the dura. A minority of dural leaks are posterolateral in location. These leaks usually do not have an identifiable anatomic cause. We have anecdotally observed cases of posterolateral leaks caused by osseous spicules and sought to describe this phenomenon. METHODS: We retrospectively reviewed our imaging database, searching for cases of posterolateral CSF leaks caused by osseous spicules. We identified and included three such patients and reviewed imaging and clinical information from each patient. RESULTS: All three patients had been diagnosed using hyperdynamic CT myelography or conventional CT myelography. Their imaging showed dorsal epidural fluid collections that were related to posterolateral leaks adjacent to dorsal osseous spicules. CONCLUSION: Dorsal osseous spicules have the potential to cause posterolateral CSF leaks.

Diagnostic Yield of Intrathecal Gadolinium MR Myelography for CSF Leak Localization.

PURPOSE: Intrathecal gadolinium magnetic resonance (MR) myelography can be used to localize various types of spinal cerebrospinal fluid (CSF) leaks; however, its diagnostic yield is not well known. We sought to determine the diagnostic yield of MR myelography in patients with spontaneous intracranial hypotension. METHODS: A retrospective review was performed on all patients who had undergone intrathecal gadolinium MR myelography at our institution from 2002 to 2020 for suspected spinal CSF leak. The MR myelography images were reviewed for the presence or absence of a spinal CSF leak site. Images were also evaluated for the presence an extradural fluid collection. RESULTS: A total of 97 patients were included in the final cohort. The average age was 52.6 years; 67.0% were female, 4 patients underwent 2 examinations each, yielding a total of 101 MR myelograms. The source of a spinal CSF leak was localized in 14 patients. The diagnostic yield for CSF leak localization on intrathecal gadolinium MR myelography was 14/101 (13.9%) per GdM examination and 14/97 (14.4%) per patient. Among the subset of patients without extradural fluid collections, the yield was 15.7% per examination. All detected leaks were either CSF-venous fistulas or distal nerve root sleeve tears. CONCLUSION: Intrathecal gadolinium MR myelography is capable of localizing CSF-venous fistulas and distal nerve root sleeve tears; however, our data show that it has a limited diagnostic yield. We suggest that other modalities may be a better first step before attempting intrathecal gadolinium MR myelography.

Utility of CT venography in monitoring stent patency in idiopathic intracranial hypertension: retrospective single-center study.

BACKGROUND: Cerebral venous sinus stenting is an established treatment for patients with idiopathic intracranial hypertension (IIH), refractory to medical management and with stenotic venous sinus on conventional cerebral venography. Currently, there are no clear guidelines on optimal noninvasive imaging modality for routine post-stenting follow-up. We investigated diagnostic yield of CT venography (CTV) for evaluation of stent patency. METHODS: We reviewed our clinical database of patients with a diagnosis of IIH, who underwent stenting of stenotic transverse or transverse/sigmoid sinus junction. Patients who had follow-up CTVs after more than 30 days were included in the final study group. All CTVs were reviewed by two readers for in-stent thrombosis, extrinsic stent compression, juxta-stent stenosis, and new contralateral venous sinus stenosis. Inter-observer agreement and association of stent patency with clinical outcomes (headache and papilledema) were assessed. RESULTS: In all 36 included patients with 38 cerebral venograms for stenting, follow-up CTVs demonstrated adequate opacifications of the venous sinuses and stents for confident evaluation for in-stent thrombosis, extrinsic stent compression, juxta-stent stenosis, and new contralateral venous sinus stenosis, with inter-observer agreement coefficient of 0.7, 1.0, 0.8, and 1.0 respectively. Association between abnormal CTV and higher rates of persistent headache and lower rates of headache improvement/resolution was statistically significant (P-value of 0.01). CONCLUSION: CTV is a reliable noninvasive imaging modality for evaluation of cerebral venous sinuses and stent patency following treatment of idiopathic intracranial hypertension with venous sinus stenting and could be used as a routine follow-up study.

Liver Surface Nodularity Score Allows Prediction of Cirrhosis Decompensation and Death.

Purpose To determine whether use of the liver surface nodularity (LSN) score, a quantitative biomarker derived from routine computed tomographic (CT) images, allows prediction of cirrhosis decompensation and death. Materials and Methods For this institutional review board-approved HIPAA-compliant retrospective study, adult patients with cirrhosis and Model for End-Stage Liver Disease (MELD) score within 3 months of initial liver CT imaging between January 3, 2006, and May 30, 2012, were identified from electronic medical records (n = 830). The LSN score was measured by using CT images and quantitative software. Competing risk regression was used to determine the association of the LSN score with hepatic decompensation and overall survival. A risk model combining LSN scores (<3 or ≥3) and MELD scores (<10 or ≥10) was created for predicting liver-related events. Results In patients with compensated cirrhosis, 40% (129 of 326) experienced decompensation during a median follow-up period of 4.22 years. After adjustment for competing risks including MELD score, LSN score (hazard ratio, 1.38; 95% confidence interval: 1.06, 1.79) was found to be independently predictive of hepatic decompensation. Median times to decompensation of patients at high (1.76 years, n = 48), intermediate (3.79 years, n = 126), and low (6.14 years, n = 152) risk of hepatic decompensation were significantly different (P < .001). Among the full cohort with compensated or decompensated cirrhosis, 61% (504 of 830) died during the median follow-up period of 2.26 years. After adjustment for competing risks, LSN score (hazard ratio, 1.22; 95% confidence interval: 1.11, 1.33) and MELD score (hazard ratio, 1.08; 95% confidence interval: 1.06, 1.11) were found to be independent predictors of death. Median times to death of patients at high (0.94 years, n = 315), intermediate (2.79 years, n = 312), and low (4.69 years, n = 203) risk were significantly different (P < .001). Conclusion The LSN score derived from routine CT images allows prediction of cirrhosis decompensation and death. ©RSNA, 2016 Online supplemental material is available for this article.

Transplanted Endothelial Progenitor Cells Improve Ischemia Muscle Regeneration in Mice by Diffusion Tensor MR Imaging.

Endothelial progenitor cells (EPCs) play an important role in repairing ischemia tissues. Diffusion tensor imaging (DTI) was applied to detect the architectural organization of skeletal muscle. This study investigated the feasibility and accuracy of using the DTI to evaluate effectiveness of EPCs treatment. Mouse bone marrow-derived EPCs were isolated, cultured, characterized, and transplanted to hindlimb ischemia mice model. DTI was performed on the hindlimb at postischemia time points. The edema regions of diffusion restriction (high signal in diffusion weighted imaging) were decreased in the ischemic muscle of EPCs treated mice after 14 days compared with the controls. These results from DTI show the lower apparent diffusion coefficient and eigenvalues (λ1, λ2, and λ3) and the higher fractional anisotropy and fiber counts of ischemic muscle on 7 and 14 days after EPCs treatment compared to the controls. There was a significant correlation between fiber counts calculated by DTI and survival fibers evaluated by histological section (r = 0.873, P < 0.01). Our study demonstrated that the time frame for muscle fiber regeneration after EPCs transplantation was significantly shortened in vivo. DTI could be a useful tool for noninvasive evaluation of muscle tissue damage and repair in animal models and patient with ischemic diseases.

Increased visceral to subcutaneous fat ratio is associated with decreased overall survival in patients with metastatic melanoma receiving anti-angiogenic therapy.

BACKGROUND: Body fat distribution is an emerging prognostic indicator in patients treated with anti-angiogenic (AA) therapy. We sought to evaluate the association of visceral and subcutaneous fat with progression free survival (PFS) and overall survival (OS) in patients with metastatic melanoma treated with AA therapy. METHODS: Stage IV melanoma patients received bevacizumab ± interferon-alpha. Total abdominal fat, visceral fat area (VFA) and subcutaneous fat area (SFA) were measured at L3-L4 on CT images (cm(2)). PFS and OS were estimated by the Kaplan-Meier method. Cox proportional hazards model was used to assess the association of fat and clinical variables with PFS and OS. Prediction accuracy was evaluated using receiver operating characteristic curve with area under the curve (AUC). RESULTS: Forty-two patients were evaluated. Median VFA/SFA and body mass index (BMI) were used to group patients into high and low cohorts. PFS and OS were significantly decreased in patients with high VFA/SFA versus low (PFS, p=0.009; OS, p = 0.007), but not for BMI (PFS, p=0.774; OS, p=0.881). VFA/SFA, LDH and liver metastasis (LM) were predictors of PFS and OS on multivariate analysis. A prognostic score combining VFA/SFA, LDH, and presence or absence of LM had a higher accuracy for predicting PFS at 3 months (AUC 0.759) and OS at 24 months (AUC 0.846) than LDH and LM alone (PFS, AUC 0.705; OS, AUC 0.786). CONCLUSION: Increased VFA/SFA is associated with decreased PFS and OS in patients with metastatic melanoma treated with AA therapy, indicating body fat distribution is an important prognostic factor.

Predicting Overall Survival in Patients With Metastatic Melanoma on Antiangiogenic Therapy and RECIST Stable Disease on Initial Posttherapy Images Using CT Texture Analysis.

OBJECTIVE: The purpose of this study was to use CT texture analysis to predict overall survival (OS) in patients with metastatic melanoma and stable disease (SD) according to the Response Evaluation Criteria in Solid Tumors (RECIST) on initial posttherapy CT images. MATERIALS AND METHODS: This retrospective study included 42 patients with metastatic melanoma who received bevacizumab therapy in the context of a randomized prospective phase II clinical trial. Target lesions on the baseline and initial posttherapy contrast-enhanced CT examinations were evaluated by CT texture analysis using TexRAD software before and after image filtering in patients with RECIST SD on initial posttherapy images. Cox proportional hazards models were used to assess the associations of CT texture analysis measurements and of other patient factors with OS. The AUC was used to evaluate predictive accuracy. RESULTS: In multivariate analysis (in 23 patients with RECIST SD; median OS, 1.51 years), absolute change in mean positive pixels at spatial scaling filter of 4 mm, change in tumor size, and baseline serum lactate dehydrogenase (LDH) level were predictors of OS (hazard ratio [HR] = 5.05 for decrease in mean positive pixels at spatial scaling filter of 4 mm vs increase, p = 0.007; HR = 4.14 for > 5% increase in tumor size vs otherwise, p = 0.025; and HR = 1.29 for every 100 IU/L increase in baseline LDH level, p = 0.068). A prognostic index containing these three factors was highly accurate for predicting OS at 18 months (AUC = 0.917). CONCLUSION: In patients with metastatic melanoma and RECIST SD on initial post-therapy CT images, a model incorporating CT texture analysis of target lesions, tumor size changes, and baseline LDH levels was highly accurate in predicting OS.