Imaging of Drug-Related Vasculopathy

Illicit and recreational drugs, such as cocaine, heroin, amphetamines, and marijuana, can result in drug-related vasculitis or vasculopathy. Similarly, the use of certain antithyroid, oncologic, and immunosuppressive medications for therapeutic purposes can lead to vasculopathy. This in turn may result in significant complications in the central nervous system, including intracranial hemorrhage and stroke. Cocaine abuse can also lead to midline destructive lesions of the sinonasal complex. MR imaging, Vessel Wall imaging, and CT/CTA are valuable imaging tools for the evaluation of patients with suspected drug-induced vasculopathy or vasculitis. This article reviews the pathomechanism, clinical presentation, and imaging findings of vasculopathy related to drug abuse and prescribed medications.

Intradural Extramedullary Tumors and Associated Syndromes

Most intradural tumors are located within the intradural extramedullary compartment, and the most common tumors are schwannomas and meningiomas. Other less common neoplasms include neurofibroma, solitary fibrous tumor, myxopapillary ependymoma, lymphoma, metastatic leptomeningeal disease, malignant peripheral nerve sheath tumor, and paraganglioma. Patients usually present with gait ataxia, radicular pain, and motor and sensory deficits due to chronic compressive myelopathy or radiculopathy. MRI is the modality of choice for detecting and evaluating intradural extramedullary spinal tumors. This imaging technique helps narrow the differential diagnosis and therefore decide treatment.

Diagnostic Accuracy of Centrally Restricted Diffusion Sign in Cerebral Metastatic Disease: Differentiating Radiation Necrosis from Tumor Recurrence

Purpose: The centrally restricted diffusion sign of diffusion-weighted imaging (DWI) is associated with radiation necrosis (RN) in treated gliomas. Our goal was to evaluate its diagnostic accuracy to distinguish RN from tumor recurrence (TR) in treated brain metastases. Methods: Retrospective study of consecutive patients with brain metastases who developed a newly centrally necrotic lesion after radiotherapy (RT). One reader placed regions of interest (ROI) in the enhancing solid lesion and the non-enhancing central necrosis on the apparent diffusion coefficient (ADC) map. Two readers qualitatively assessed the presence of the centrally restricted diffusion sign. The final diagnosis was made by histopathology (n = 39) or imaging follow-up (n = 2). Differences between groups were assessed by Fisher's exact or Mann-Whitney U tests. Diagnostic accuracy and inter-reader agreement were evaluated using receiver operating characteristic (ROC) curve analysis and kappa scores. Results: Forty-one lesions (32 predominant RN; 9 predominant TR) were analyzed. An ADC value ≤ 1220 × 10-6 mm2/s (sensitivity 74%, specificity 89%, area under the curve [AUC] .85 [95% confidence interval {CI}, .70-.94] P < .0001) from the necrosis and an ADC necrosis/enhancement ratio ≤1.37 (sensitivity 74%, specificity 89%, AUC .82 [95% CI, .67-.93] P < .0001) provided the highest performance for RN diagnosis. The qualitative centrally restricted diffusion sign had a sensitivity of 69% (95% CI, .50-.83), specificity of 77% (95% CI, .40-.96), and a moderate (k = .49) inter-reader agreement for RN diagnosis. Conclusions: Radiation necrosis is associated with lower ADC values in the central necrosis than TR. A moderate interobserver agreement might limit the qualitative assessment of the centrally restricted diffusion sign.

Case 309: Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy

HISTORY

A 64-year-old man presented with a 6-month history of lightheadedness and intermittent balance and coordination difficulties. Two months before admission, symptoms became more substantial and persistent, with a worsening sense of disequilibrium and unsteady gait. He reported difficulties pronouncing words and mild word-finding difficulties. His wife noted a change in his cognition and memory over the same time. His medical history included well-controlled chronic obstructive pulmonary disease (COPD) secondary to a long history of smoking with associated unintentional 30-lb (13.6-kg) weight loss over the previous 3 years, for which chest CT scanning was performed, revealing no abnormality. On clinical examination, the patient was alert and oriented but had slurred speech. A positive Romberg sign was noted, finger-to-nose and hand rapid alternating movement tests revealed impairment on the right side, and his gait was ataxic. The motor examination revealed normal muscle tone, bulk, and power in the upper and lower extremities. Sensory testing results were normal. Initial MRI of the brain at admission revealed abnormal findings in the left supratentorial brain. Of note, this patient's presentation predated the COVID-19 pandemic. Cerebrospinal fluid (CSF) analysis revealed predominant pleocytosis (23 × 106/L; normal range, [0-5] × 106/L) (78% lymphocytes, 22% monocytes), elevated protein level (1.23 g/L; normal range, 0.19-0.64 g/L), oligoclonal bands (faint one or two), and a high immunoglobulin G (IgG) index (0.130 g/L; normal reference, ≤0.059 g/L). Despite extensive initial work-up for inflammatory, infectious, autoimmune, or neoplastic causes, a definitive diagnosis was not reached. Thus, repeat MRI of the brain was performed 2 weeks after admission.

Aetiology of extracranial carotid free-floating thrombus in a prospective multicentre cohort

Background

Carotid free-floating thrombi (FFT) in patients with acute transient ischaemic attack (TIA)/stroke have a high risk of early recurrent stroke. Management depends on aetiology, which can include local plaque rupture, dissection, coagulopathy, malignancy and cardioembolism. Our objectives were to classify the underlying aetiology of FFT and to estimate the proportion of patients with underlying stenosis requiring revascularisation.

Methods

We prospectively enrolled consecutive patients presenting to three comprehensive stroke centres with acute TIA/stroke and ipsilateral internal carotid artery FFT. The aetiology of FFT was classified as: carotid atherosclerotic disease, carotid dissection, cardioembolism, both carotid atherosclerosis and cardioembolism, or embolic stroke of uncertain source (ESUS). Patients with carotid atherosclerosis were further subclassified as having ≥50% or <50% stenosis.

Results

We enrolled 83 patients with confirmed FFT. Aetiological assessments revealed 66/83 (79.5%) had carotid atherosclerotic plaque, 4/83 (4.8%) had a carotid dissection, 10/83 (12%) had both atrial fibrillation and carotid atherosclerotic plaque and 3/83 (3.6%) were classified as ESUS. Of the 76 patients with atherosclerotic plaque (including those with atrial fibrillation), 40 (52.6%) had ≥50% ipsilateral stenosis.

Conclusions

The majority of symptomatic carotid artery FFT are likely caused by local plaque rupture, more than half of which are associated with moderate to severe carotid stenosis requiring revascularisation. However, a significant number of FFTs are caused by non-atherosclerotic mechanisms warranting additional investigations.

Case 309

HISTORY

A 64-year-old man presented with a 6-month history of lightheadedness, intermittent balance, and coordination difficulties. Two months before admission, symptoms became more substantial and persistent, with a worsening sense of disequilibrium and unsteady gait. He reported difficulties pronouncing words and mild word-finding difficulties. His wife noted a change in his cognition and memory over the same time. His medical history included well-controlled chronic obstructive pulmonary disease (COPD) secondary to a long history of smoking with associated unintentional 30-lb (13.6-kg) weight loss over the previous 3 years, for which chest CT scanning was performed, revealing no abnormality. On clinical examination, the patient was alert and oriented but had slurred speech. A positive Romberg sign was noted, finger-to-nose and hand rapid alternating movement tests revealed impairment on the right side, and his gait was ataxic. The motor examination revealed normal muscle tone, bulk, and power in the upper and lower extremities. Sensory testing results were normal. Initial MRI of the brain at admission revealed abnormal findings in the left supratentorial brain (Figs 1-3). Of note, this patient's presentation predated the COVID-19 pandemic. Cerebrospinal fluid analysis revealed predominant pleocytosis (23 × 10⁶/L; normal range, [0-5] × 10⁶/L) (78% lymphocytes, 22% monocytes), elevated protein level (1.23 g/L; normal range, 0.19-0.64 g/L), oligoclonal bands (faint one or two), and a high immunoglobulin G index (0.130 g/L; normal reference, ≤0.059 g/L). Despite extensive initial work-up for inflammatory, infectious, autoimmune, or neoplastic causes, a definitive diagnosis was not reached. Thus, repeat MRI of the brain was performed 2 weeks after admission (Fig 4).

Rule-based natural language processing for automation of stroke data extraction: a validation study

PURPOSE

Data extraction from radiology free-text reports is time consuming when performed manually. Recently, more automated extraction methods using natural language processing (NLP) are proposed. A previously developed rule-based NLP algorithm showed promise in its ability to extract stroke-related data from radiology reports. We aimed to externally validate the accuracy of CHARTextract, a rule-based NLP algorithm, to extract stroke-related data from free-text radiology reports.

METHODS

Free-text reports of CT angiography (CTA) and perfusion (CTP) studies of consecutive patients with acute ischemic stroke admitted to a regional stroke center for endovascular thrombectomy were analyzed from January 2015 to 2021. Stroke-related variables were manually extracted as reference standard from clinical reports, including proximal and distal anterior circulation occlusion, posterior circulation occlusion, presence of ischemia or hemorrhage, Alberta stroke program early CT score (ASPECTS), and collateral status. These variables were simultaneously extracted using a rule-based NLP algorithm. The NLP algorithm's accuracy, specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were assessed.

RESULTS

The NLP algorithm's accuracy was > 90% for identifying distal anterior occlusion, posterior circulation occlusion, hemorrhage, and ASPECTS. Accuracy was 85%, 74%, and 79% for proximal anterior circulation occlusion, presence of ischemia, and collateral status respectively. The algorithm confirmed the absence of variables from radiology reports with an 87-100% accuracy.

CONCLUSIONS

Rule-based NLP has a moderate to good performance for stroke-related data extraction from free-text imaging reports. The algorithm's accuracy was affected by inconsistent report styles and lexicon among reporting radiologists.

Differentiating Carotid Free-Floating Thrombus From Atheromatous Plaque Using Intraluminal Filling Defect Length on CTA: A Validation Study

OBJECTIVE

To validate a previously proposed filling defect length threshold of >3.8 mm on CT angiography (CTA) to discriminate between free-floating thrombus (FFT) and plaque of atheroma.

METHODS

This was a prospective multicenter observational study of 100 participants presenting with TIA/stroke symptoms and a carotid intraluminal filling defect on initial CTA. Follow-up CTA was obtained within 1 week and at weeks 2 and 4 if the intraluminal filling defect was unchanged in length. Resolution or decreased length was diagnostic of FFT, whereas its static appearance after 4 weeks was indicative of plaque. Diagnostic accuracy of FFT length was assessed by receiver operating characteristic analysis.

RESULTS

Ninety-five participants (mean [SD] age 68 [13] years, 61 men, 83 participants with FFT, 12 participants with a plaque) were evaluated. The >3.8-mm threshold had a sensitivity of 88% (73 of 83) (95% confidence interval [CI] 78%-94%) and specificity of 83% (10 of 12) (95% CI 51%-97%) (area under the curve 0.91, p < 0.001) for the diagnosis of FFT. The optimal length threshold was >3.64 mm with a sensitivity of 89% (74 of 83) (95% CI 80%-95%) and specificity of 83% (10 of 12) (95% CI 51%-97%). Adjusted logistic regression showed that every 1-mm increase in intraluminal filling defect length is associated with an increase in odds of FFT of 4.6 (95% CI 1.9-11.1, p = 0.01).

CONCLUSION

CTA enables accurate differentiation of FFT vs plaque using craniocaudal length thresholds.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT02405845.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that in patients with TIA/stroke symptoms, the presence of CTA-identified filling defects of lengths >3.8 mm accurately discriminates FFT from atheromatous plaque.