Dynamic CT Myelography Research Articles

Spinal Compliance Curves: Preliminary Experience with a New Tool for Evaluating Suspected CSF Venous Fistulas on CT Myelography in Patients with Spontaneous Intracranial Hypotension.

Craniospinal space compliance reflects the distensibility of the spinal and intracranial CSF spaces as a system. Craniospinal space compliance has been studied in intracranial pathologies, but data are limited in assessing it in spinal CSF leak. This study describes a method to estimate craniospinal space compliance using saline infusion during CT myelography and explores the use of craniospinal space compliance and pressure-volume curves in patients with suspected cerebrospinal-venous fistula. Patients with suspected cerebrospinal-venous fistula underwent dynamic CT myelography. During the procedure, 1- to 5-mL boluses of saline were infused, and incremental changes in CSF pressure were recorded. These data were used to plot craniospinal space compliance curves. We calculated 3 quantitative craniospinal space compliance parameters: overall compliance, compliance at opening pressure, and the pressure volume index. These variables were compared between patients with confirmed cerebrospinal-venous fistula and those with no confirmed source of CSF leak. Thirty-four CT myelograms in 22 patients were analyzed. Eight of 22 (36.4%) patients had confirmed cerebrospinal-venous fistulas. Bolus infusion was well-tolerated with no complications and transient headache in 2/34 (5.8%). Patients with confirmed cerebrospinal-venous fistulas had higher compliance at opening pressure and overall compliance (2.6 versus 1.8 mL/cm H20, P < .01). There was no difference in the pressure volume index (77.5 versus 54.3 mL, P = .13) between groups. A method of deriving craniospinal space compliance curves using saline intrathecal infusion is described. Preliminary analysis of craniospinal space compliance curves provides qualitative and quantitative information about pressure-volume dynamics and may serve as a diagnostic tool in patients with known or suspected cerebrospinal-venous fistulas.

Interdisciplinary Diagnosis and Management of Cerebrospinal Fluid Leakage Due to a Meningeal Diverticulum: a Case Report

Cerebrospinal fluid leakage through meningeal diverticula represents a diagnostic and therapeutic challenge comparatively rarely encountered in the interdisciplinary management of spontaneous intracranial hypotension (SIH). Several false-positive CSF leakage signs may be observed during the imaging work-up of SIH. A 27-year-old female with orthostatic headache showing marked spinal epidural CSF collections and MRI signs of intracranial hypotension underwent a blind and CT-guided epidural blood patch (EBP) of a pathological T9/10 meningeal diverticulum (MD), detected by dynamic CT myelography (dCTM). After initial good imaging and symptomatic improvement, recurrent symptoms and a large left-sided subdural hematoma required neurosurgical MD ligation, with persisting clinical success. The following aspects of this brief report are remarkable: added value of dCTM to synchronously detect true CSF leakage and false-positive CSF leakage signs, near-complete resolution of spinal epidural CSF collections after CT fluoroscopy–guided EBP, interdisciplinary diagnosis, and definite management of CSF leakage through an anomalous MD.

Cryptogenic Cerebrospinal Fluid Leaks in Spontaneous Intracranial Hypotension: Role of Dynamic CT Myelography.

Purpose To propose a modified dynamic CT myelographic technique to locate cerebrospinal fluid (CSF) leaks, also known as cryptogenic leaks, in patients with spontaneous intracranial hypotension (SIH) in whom previous imaging did not show the dural breach. Materials and Methods This retrospective analysis included 74 consecutive patients with SIH and a myelographically proven CSF leak who were evaluated between February 2013 and October 2017. In 14 patients, dynamic CT myelography in the prone or lateral position showed the exact leakage point after unsuccessful previous imaging. During image analysis, the first time point showing extrathecal contrast material was defined as the site of dural breach point. Results Mean population age was 44 years (range, 25-65 years [nine women; mean age, 44 years; age range, 25-65 years] [five men; mean age, 46 years; age range, 29-61 years]). All patients had previously undergone spine MRI, conventional dynamic myelography, and CT myelography. Subsequent dynamic CT myelography covered a mean range of seven vertebral levels. The leak was caused by a calcified microspur in 10 patients and by a dural tear at the axilla of a spinal nerve root in the remaining four. The mean volume CT dose index of dynamic CT myelography was 107 mGy (range, 12-246 mGy), and the mean dose-length product was 1347 mGy·cm (range, 550-3750 mGy·cm). Conclusion Dynamic CT myelography is a valuable adjunctive tool with which to identify the precise location of a dural tear when other examinations are unsuccessful. © RSNA, 2018 See also the editorial by Dillon in this issue.

Imaging of lumbar spinal surgery complications.

Lumbar spine surgery for spinal stenosis is a frequently performed procedure and was the fastest growing type of surgery in the US from 1980 to 2000. With increasing surgical invasiveness, postoperative complications also tend to be higher. Cross-sectional imaging techniques (CT and MRI) are more sensitive than radiographs and play an increasingly important role in evaluation of patients with lumbar spine surgery. Their use in patients with metallic implants is somewhat limited by artefacts, which can obscure pathology and decrease accuracy and reader confidence. Metal artefact reduction techniques have been developed, which can significantly improve image quality and enable early detection of postoperative complications. Complications can occur throughout postoperative course. Early complications include hardware displacement, incidental durotomy, postoperative collections—most commonly seroma, and less likely haematoma and/or infection. Incidental durotomy with CSF leak causing intracranial hypotension has characteristic MR brain findings and diagnosis of occult leak sites have been improved with use of dynamic CT myelography. Haematomas, even when compressing the thecal sac, are usually asymptomatic. Early infection, with nonspecific MR findings, can be diagnosed accurately using dual radiotracer studies. Delayed complications include loosening, hardware failure, symptomatic new or recurrent disc herniation, peri-/epidural fibrosis, arachnoiditis, and radiculitis.Teaching Points• CT and MRI play an increasingly important role in evaluation of patients with lumbar spine surgery• Complications can occur throughout the postoperative course and early detection is critical• Artefact reduction techniques can improve image quality for early and improved detection of complications

Predicting High-Flow Spinal CSF Leaks in Spontaneous Intracranial Hypotension Using a Spinal MRI-Based Algorithm: Have Repeat CT Myelograms Been Reduced?

We adopted an imaging algorithm in 2011 in which extradural fluid on spinal MR imaging directs dynamic CT myelography. We assessed algorithm compliance and its effectiveness in reducing repeat or unnecessary dynamic CT myelograms. CT myelograms for CSF leaks from January 2011 to September 2014 were reviewed. Patients with iatrogenic leaks, traumatic brachial plexus injuries, or prior CT myelography within 2 years were excluded. Completion and results of spinal MR imaging, CT myelographic technique, and the need for repeat CT myelography or unnecessary dynamic CT myelograms were recorded. The algorithm was followed in 102 (79%) of 129 patients. No extradural fluid was detected in 75 (74%), of whom 70 (93%) had no leak, 4 (5%) had a slow leak, and 1 (1%) had a fast leak. Extradural fluid was detected in 27 (26%): 24 (89%) fast leaks, 1 (4%) slow leak, and 2 (7%) with no leaks. When the algorithm was followed, 1 (1%) required repeat CT myelography and 3 (3%) had unnecessary dynamic CT myelograms. The algorithm was breached in 27 (21%) cases, including no pre-CT myelogram MR imaging in 11 (41%), performing conventional CT myelography when extradural fluid was present in 13 (48%), and performing dynamic CT myelography when extradural fluid was absent in 3 (11%). Algorithm breaches resulted in 4 (15%) repeat CT myelograms and 3 (12%) unnecessary dynamic CT myelograms, both higher than with algorithm compliance. Using spinal MR imaging to direct CT myelography resulted in significant reduction in repeat CT myelograms to localize fast leaks with minimal unnecessary dynamic CT myelograms.

Spontaneous Intracranial Hypotension.

Spontaneous intracranial hypotension results from CSF volume depletion, nearly always from spontaneous CSF leaks. Spontaneous intracranial hypotension is increasingly diagnosed in practice; the number of atypical, unconfirmed, and doubtful cases is also increasing, as are treatment failures. These confront neurologists and create many challenges. This review provides neurologists with a guide to diagnosis, evaluation, and treatment of spontaneous intracranial hypotension. The clinical spectrum of spontaneous intracranial hypotension is expanding. Spontaneous CSF leak is considered a disorder with a variety of clinical manifestations and imaging features, sometimes quite different from what may be seen after dural puncture. The anatomy of the spontaneous CSF leak is frequently complex, with contributions from disorders of the connective tissue matrix and associated preexisting areas of dural weakness and meningeal diverticula. To locate the site of the leak, CT myelography is still the study of choice. For rapid-flow leaks, dynamic CT myelography has been very helpful, while slow-flow leaks can remain a lingering challenge. The fundamental question of whether a CSF leak is present in uncertain cases can be best answered by radioisotope cisternography. In most cases, epidural blood patch is the main treatment; however, bilevel or multilevel epidural injections are gaining some momentum as treatment for selected cases. This article outlines various clinical aspects of spontaneous intracranial hypotension, including headache characteristics, CSF changes, and imaging findings and their underlying mechanisms, as well as treatments and disease complications.

Ultrafast dynamic computed tomography myelography for the precise identification of high-flow cerebrospinal fluid leaks caused by spiculated spinal osteophytes.

Precise localization and understanding of the origin of spontaneous high-flow spinal CSF leaks is required prior to targeted treatment. This study demonstrates the utility of ultrafast dynamic CT myelography for the precise localization of high-flow CSF leaks caused by spiculated spinal osteophytes. This study reports a series of 14 patients with high-flow CSF leaks caused by spiculated spinal osteophytes who underwent ultrafast dynamic CT myelography between March 2009 and December 2010. There were 10 male and 4 female patients, with an average age of 49 years (range 37-74 years). The value of ultrafast dynamic CT myelography in depicting the CSF leak site was qualitatively assessed. In all 14 patients, ultrafast dynamic CT myelography was technically successful at precisely demonstrating the site of the CSF leak, the causative spiculated osteophyte piercing the dura, and the relationship of the implicated osteophyte to adjacent structures. Leak sites included 3 cervical, 11 thoracic, and 0 lumbar levels, with 86% of the leaks occurring from C-5 to T-7. Information obtained from the ultrafast dynamic CT myelogram was considered useful in all treated CSF leaks. Spinal osteophytes piercing the dura are a more frequent cause of high-flow CSF leaks than previously recognized. Ultrafast dynamic CT myelography adds value beyond standard dynamic myelography or digital subtraction myelography in the diagnosis and anatomical characterization of high-flow spinal CSF leaks caused by these osteophytes. This information allows for appropriate planning for percutaneous or surgical treatment.

Novel Neuroimaging Modalities in the Evaluation of Spontaneous Cerebrospinal Fluid Leaks

Although for the vast majority of patients with spontaneous intracranial hypotension knowledge of the exact site of the underlying spinal CSF leak is not necessary, it is for patients with recalcitrant symptoms. Such patients may require directed treatments such as percutaneous fibrin glue injections or surgery. A variety of MRI techniques have been shown to be able to detect CSF leaks as well and sometimes better than the "gold standard" - CT-myelography. For unusually rapid CSF leaks - particularly those ventral to the spinal cord - digital subtraction myelography or dynamic CT-myelography are indicated. Some patients with spontaneous intracranial hypotension verified by intracranial MRI are never found to have a spinal CSF leak using current techniques.

Case Series: Long segment extra-arachnoid fluid collections: Role of dynamic CT myelography in diagnosis and treatment planning

We report five patients in whom spinal MRI revealed extra-arachnoid fluid collections. These spinal fluid collections most likely resulted from accumulation of cerebrospinal fluid (CSF) from a dural leak. The patients presented with either compressive myelopathy due to the cyst or superficial siderosis (SS). All of these fluid collections were long segment, and MRI demonstrated the fluid collections but not the exact site of leak. Dynamic CT myelogram demonstrated the site of leak and helped in the management of these complicated cases. Moreover, we also found that the epicenter of the fluid collection on MRI was different from the location of the leak on a dynamic CT myelogram. Knowledge of these associations can be helpful when selecting the imaging studies to facilitate diagnosis and treatment.

When Should I Do Dynamic CT Myelography? Predicting Fast Spinal CSF Leaks in Patients with Spontaneous Intracranial Hypotension

Some patients with SIH have fast CSF leaks requiring dynamic CTM for localization; however, patients generally undergo conventional CTM before a dynamic study. Our aim was to determine whether findings on head MR imaging, spine MR imaging, or opening pressure measurements can predict fast spinal CSF leaks. A retrospective review was performed on 151 consecutive patients referred for CTM to evaluate for spinal CSF leak. Head MR imaging was evaluated for diffuse dural enhancement and "brain sag," and spine MR imaging for presence of an extradural fluid collection. The opening pressure was recorded. The CTM was scored as no leak, slow leak localized on conventional CTM, or fast leak that required dynamic CTM. Fast CSF leaks were identified in 32 (21%), slow leaks in 36 (24%), and no leak in 83 (55%) of 151 patients on initial CTM. There was significant association between spinal extra-arachnoid fluid on MR imaging and the presence of a fast leak (sensitivity 85%, specificity 79%, P < .0001). There was not significant association between fast leak and findings on head MR imaging (P = .27) or opening pressure (P = .30). If all patients with spinal extra-arachnoid CSF on MR imaging had been sent directly to dynamic CTM, repeat myelography would have been avoided in most patients with fast leaks (23 of 27; 85%). However, a minority of patients with slow or no leaks would have been converted from conventional to dynamic CTM (16 of 77; 21%). Spinal MR imaging is helpful in premyelographic evaluation of SIH.

Localization of a Rapid CSF Leak with Digital Subtraction Myelography

A 53-year-old woman with superficial siderosis underwent spinal MR imaging, which demonstrated a large cervicothoracic epidural fluid collection compatible with a CSF leak. Conventional and dynamic CT myelography failed to localize the dural tear because of rapid equilibration of myelographic contrast between the thecal sac and the extradural collection. The superior temporal resolution of digital subtraction myelography precisely localized the CSF leak preoperatively and led to the successful surgical correction of the dural tear.

Role of dynamic CT myelography in identifying the etiology of superficial siderosis

The authors report three cases of superficial siderosis with a fluid-filled spinal canal cavity communicating with the subarachnoid space. The site of communication was identified with dynamic CT myelography and the defect was surgically repaired.