Peter G. Kranz

Does Diffusion-Weighted Imaging Represent the Ischemic Core? An Evidence-Based Systematic Review

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) hyperintensity is hypothesized to represent irreversibly infracted tissue (ischemic core) in the setting of acute stroke. Measurement of the ischemic core has implications for both prognosis and therapy. We wished to assess the level of evidence in the literature supporting this hypothesis. MATERIALS AND METHODS: We performed a systematic review of the literature relating to tissue outcomes of DWI hyperintense stroke lesions in humans. The methodologic rigor of studies was evaluated by using criteria set out by the Oxford Centre for Evidence-Based Medicine. Data from individual studies were also analyzed to determine the prevalence of patients demonstrating lesion progression, no change, or lesion regression compared with follow-up imaging. RESULTS: Limited numbers of highly methodologically rigorous studies (Oxford levels 1 and 2) were available. There was great variability in observed rates of DWI lesion reversal (0%–83%), with a surprisingly high mean rate of DWI lesion reversal (24% of pooled patients). Many studies did not include sufficient data to determine the precise prevalence of DWI lesion growth or reversal. CONCLUSIONS: The available tissue-outcome evidence supporting the hypothesis that DWI is a surrogate marker for ischemic core in humans is troublingly inconsistent and merits an overall grade D based on the criteria set out by the Oxford Centre for Evidence-Based Medicine.

CT-Guided Epidural Blood Patching of Directly Observed or Potential Leak Sites for the Targeted Treatment of Spontaneous Intracranial Hypotension

BACKGROUND AND PURPOSE: Optimal diagnosis and management of spontaneous intracranial hypotension remains uncertain. CT-guided blood patching has been described but has not been evaluated in larger case series. We sought to evaluate the efficacy of CT-guided blood patching of observed or potential CSF leaks in spontaneous intracranial hypotension. MATERIALS AND METHODS: Patients referred for evaluation of spontaneous intracranial hypotension were retrospectively reviewed. Inclusion criteria were findings of intracranial hypotension on pretreatment brain MR imaging, evaluation and treatment with CT-guided myelography and blood patching, and availability of posttreatment brain MR images. Eight patients met inclusion criteria. Imaging findings, treatment details, and clinical outcomes were assessed. RESULTS: Pretreatment imaging findings included dural enhancement, tonsillar ectopia, subdural collections, and syrinx. All findings resolved or significantly improved on posttreatment imaging. Presenting clinical symptoms included positional headache, neck/interscapular/shoulder pain, and tinnitus. Headaches and neck/interscapular/shoulder pain improved in all patients; tinnitus improved in 1 of 2 patients. CSF leak sites were directly visualized in 37% of patients and were targets for patching when seen. When no direct visualization of leaks was seen, irregular spinal nerve root diverticula were targeted as potential leak sites. The average number of blood patching sessions was 3 (range, 1–6) and the average number of individual sites patched per session was 5 (range, 1–10). CONCLUSIONS: Our results suggest that CT-guided blood patching targeting observed or potential leak sites can be effective in the treatment of intracranial hypotension. Prospective controlled studies are needed to confirm efficacy and compare outcomes with other treatment options.

JOURNAL CLUB: Incidental Thyroid Nodules Detected at Imaging: Can Diagnostic Workup Be Reduced by Use of the Society of Radiologists in Ultrasound Recommendations and the Three-Tiered System?

OBJECTIVE The purpose of this study was to determine the number of thyroid nodule workups that could be eliminated and the number of malignant tumors that would be missed if the Society of Radiologists in Ultrasound (SRU) recommendations and the three-tiered system were applied to incidental thyroid nodules (ITN) detected at imaging. MATERIALS AND METHODS This retrospective study included ITN in 390 consecutively registered patients who underwent ultrasound-guided fine-needle aspiration of one or more thyroid nodules from July 2010 to June 2011. Images were reviewed, and nodules were categorized according to two workup criteria: ITN seen on ultrasound images were categorized according to SRU recommendations, and those seen on CT, MR, or PET/CT images were classified according to the three-tiered risk-categorization system. RESULTS In this study 114 of 390 (29%) patients had nodules first detected incidentally during imaging studies, and 107 patients met the inclusion criteria. These patients had 47 ITN seen at ultrasound and 60 ITN seen at either CT, MRI, or PET/CT. If the SRU recommendations had been applied, 14 of 47 (30%) patients with ITN on ultrasound images would not have received fine-needle aspiration and one of four cases of cancer would have been missed. The missed malignant tumor was a 14-mm localized papillary carcinoma. If the three-tiered system had been applied, 21 of 60 (35%) patients with ITN on CT, MR, or PET/CT images would not have received fine-needle aspiration, but none of the three malignancies would have been missed. Overall, 35 of 107 (33%) of patients with ITN did not meet the SRU recommendations or the three-tiered criteria. CONCLUSION Use of the SRU recommendations and three-tiered system can reduce the workup of ITN by one third compared with current practice without specific guidelines. One case of localized papillary carcinoma was missed when the SRU recommendations were used.

Dural Sinus Thrombosis: Sources of Error in Image Interpretation

OBJECTIVE The purpose of this article is to bring some of the potential causes of false-positive and false-negative interpretations of dural sinus thrombosis (DST) on cross-section imaging studies to the attention of radiologists. CONCLUSION The prompt diagnosis of DST can be important in many cases and a false-positive diagnosis can cause a delay in establishing the correct diagnosis as well as lead to implementation of inappropriate therapy. We hope that this article helps to reduce the number of such cases in the daily practice of the reader.

CT fluoroscopy-guided cervical interlaminar steroid injections: safety, technique, and radiation dose parameters.

BACKGROUND AND PURPOSE: Cervical epidural steroid injections are approached with trepidation because of concerns over safety, including direct spinal cord injury. CT fluoroscopy is an alternative to conventional fluoroscopy that could potentially help reduce the risk of injury by providing improved localization of the needle tip. We sought to determine rates of technical success and risk of complications in our initial cohort of patients treated with cervical interlaminar ESI performed under CTF guidance. MATERIALS AND METHODS: In this retrospective case series, we reviewed procedural details and CTF images of 53 consecutive cervical interlaminar ESIs performed on 50 patients over a period of 8 months. Rates of technical success, incidence of complications, procedure times, and factors that influence radiation exposure were examined. RESULTS: No symptomatic procedural complications were observed. A single case of intrathecal contrast injection was observed, from which the patient was asymptomatic. The remaining injections were all technically successful. Injections were performed at every cervical level, as high as C1-C2. Total procedure times averaged less than 20 minutes. Average CT fluoroscopic time was 24 seconds and median tube current was 70 mA. CONCLUSIONS: CTF-guided cervical interlaminar ESI can be performed at all levels in the cervical spine with a low rate of procedural complications. Short total procedure times, CT-fluoroscopy times, and reduced tube current make this procedure a practical alternative to cervical ESI performed under conventional fluoroscopy.

Bilateral Retropharyngeal Parathyroid Hyperplasia Detected with 4D Multidetector Row CT

SUMMARY: We present a case of bilateral retropharyngeal parathyroid hyperplasia detected with 4D-CT in a patient with persistent primary hyperparathyroidism and failed neck exploration. We discuss the embryologic basis of ectopic retropharyngeal parathyroid adenomas and hyperplasia and the utility of 4D-CT in their localization for surgical planning.

Spinal Meningeal Diverticula in Spontaneous Intracranial Hypotension: Analysis of Prevalence and Myelographic Appearance

The prevalence and appearance of spinal meningeal diverticula in patients with spontaneous intracranial hypotension and healthy controls were compared by these authors. They used CT myelograms in 19 symptomatic patients and 18 healthy controls and found no differences in the numbers and morphologies of diverticula between the groups. Thus, the role of these diverticula in intracranial hypotension is still not clear. BACKGROUND AND PURPOSE: Spinal meningeal diverticula have been implicated in the pathogenesis of spontaneous intracranial hypotension and have been proposed as both diagnostic features of and therapeutic targets for the condition. We compared the prevalence and myelographic appearance of spinal diverticula in patients with SIH and healthy controls. MATERIALS AND METHODS: Patients satisfying the ICHD-2 criteria for SIH were retrospectively identified. CT myelograms of 19 patients with SIH were compared with CT myelograms of 18 control patients. Images were reviewed by 2 blinded neuroradiologists. The prevalence, morphology (round versus multilobulated), size, and location (cervical, upper thoracic, lower thoracic, or lumbar) of spinal meningeal diverticula were analyzed. RESULTS: There was no difference in the proportion of patients with diverticula in the SIH group compared with the control group (68% versus 44%, P = .14) or in the mean number of diverticula per patient (6.3 versus 2.2, P = .099). No difference was seen in the morphology (P = .95) or size (P = .71) of diverticula between groups. There was a difference between groups that just reached statistical significance (P = .050) in the location of the diverticula along the spinal axis, but substantial overlap was seen between groups for all spinal locations. CONCLUSIONS: Despite the well-established association between spinal meningeal diverticula and SIH, we found no difference in the prevalence or myelographic appearance of diverticula in patients with SIH compared with controls. Further investigation into the role of diverticula in the diagnosis and treatment of SIH is necessary.

Gender and Age Interact to Affect Early Outcome after Intracerebral Hemorrhage

Background Intracerebral hemorrhage (ICH) is a common and devastating form of cerebrovascular disease. In ICH, gender differences in outcomes remain relatively understudied but have been examined in other neurological emergencies. Further, a potential effect of age and gender on outcomes after ICH has not been explored. This study was designed to test the hypothesis that age and gender interact to modify neurological outcomes after ICH. Methods Adult patients admitted with spontaneous primary supratentorial ICH from July 2007 through April 2010 were assessed via retrospective analysis of an existing stroke database at Duke University. Univariate analysis of collected variables was used to compare gender and outcome. Unfavorable outcome was defined as discharge to hospice or death. Using multivariate regression, the combined effect of age and gender on outcome after ICH was analyzed. Results In this study population, women were younger (61.1+14.5 versus 65.8+17.3 years, p=0.03) and more likely to have a history of substance abuse (35% versus 8.9%, p<0.0001) compared to men. Multivariable models demonstrated that advancing age had a greater effect on predicting discharge outcome in women compared to men (p=0.02). For younger patients, female sex was protective; however, at ages greater than 60 years, female sex was a risk factor for discharge to hospice or death. Conclusion While independently associated with discharge to hospice or death after ICH, the interaction effect between gender and age demonstrated significantly stronger correlation with early outcome after ICH in a single center cohort. Prospective study is required to verify these findings.

CT Fluoroscopy–Assisted Cervical Transforaminal Steroid Injection: Tips, Traps, and Use of Contrast Material

OBJECTIVE CT fluoroscopy-assisted cervical transforaminal steroid injection is an effective therapeutic option for cervical radiculopathy, yet it is approached with trepidation by some interventionalists. CT fluoroscopy is superior to conventional fluoroscopy for delineating complex anatomic relations in the neck but must be combined with careful technique to avoid rare but serious complications. We describe the anatomy of the neural foramen, our technique of CT fluoroscopy-assisted cervical transforaminal steroid injection, and the CT appearance of appropriate and inappropriate needle positions. CONCLUSION Understanding anatomy will help to avoid complications and optimize the therapeutic potential of cervical transforaminal steroid injection. Use of contrast material for CT fluoroscopic guidance facilitates appropriate needle positioning and reduces the risk of complications.

Comparison of Acoustic Radiation Force Impulse Imaging Derived Carotid Plaque Stiffness With Spatially Registered MRI Determined Composition

Measurements of plaque stiffness may provide important prognostic and diagnostic information to help clinicians distinguish vulnerable plaques containing soft lipid pools from more stable, stiffer plaques. In this preliminary study, we compare in vivo ultrasonic Acoustic Radiation Force Impulse (ARFI) imaging derived measures of carotid plaque stiffness with composition determined by spatially registered Magnetic Resonance Imaging (MRI) in five human subjects with stenosis >50%. Ultrasound imaging was implemented on a commercial diagnostic scanner with custom pulse sequences to collect spatially registered 2D longitudinal B-mode and ARFI images. A standardized, multi-contrast weighted MRI sequence was used to obtain 3D Time of Flight (TOF), T1 weighted (T1W), T2 weighted (T2W), and Proton Density Weighted (PDW) transverse image stacks of volumetric data. The MRI data was segmented to identify lipid, calcium, and normal loose matrix components using commercially available software. 3D MRI segmented plaque models were rendered and spatially registered with 2D B-mode images to create fused ultrasound and MRI volumetric images for each subject. ARFI imaging displacements in regions of interest (ROIs) derived from MRI segmented contours of varying composition were compared. Regions of calcium and normal loose matrix components identified by MRI presented as homogeneously stiff regions of similarly low (typically ≈ 1 μm) displacement in ARFI imaging. MRI identified lipid pools > 2 mm2, found in three out of five subjects, presented as softer regions of increased displacement that were on average 1.8 times greater than the displacements in adjacent regions of loose matrix components in spatially registered ARFI images. This work provides early evidence supporting the use of ARFI imaging to noninvasively identify lipid regions in carotid artery plaques in vivo that are believed to increase the propensity of a plaque to rupture. Additionally, the results provide early training data for future studies and aid in the interpretation and possible clinical utility of ARFI imaging for identifying the elusive vulnerable plaque.