Imaging for Predicting Hemorrhagic Transformation of Acute Ischemic Stroke-A Narrative Review.

Hemorrhagic transformation is caused by extravasation of blood products from vessels after acute ischemic stroke. It is an undesirable and potentially devastating complication, which occurs in 10%-40% of clinical cases. Hemorrhagic transformation is classified into four subtypes based on European cooperative acute stroke study II. Predicting hemorrhagic complications at presentation can be useful life saving/altering decisions for the patient. Also, understanding the mechanisms of hemorrhagic transformation can lead to new treatments and intervention measures. We highlighted various imaging techniques that have been used to predict hemorrhagic transformation. Specifically, we looked at the usefulness of perfusion and permeability imaging for hemorrhagic transformation. Use of imaging to predict hemorrhagic transformation could change patient management that may lead to the prevention of hemorrhagic transformation before it occurs. We concluded that the current evidence is not strong enough to rely on these imaging parameters for predicting hemorrhagic transformation and more studies are required.

Variation in CT perfusion protocol has implications on defining irreversibly damaged ischemic brain parenchyma.

KEY POINTS: • Computed tomographic perfusion (CTP) is increasingly being used in the characterization of brain ischemia.• Variations in post-processing protocols continue to be a challenge, resulting in a slight variation of CTP results.• We need to adopt a universal acquisition protocol to help optimize output of CTP.

Bleomycin for Head and Neck Venolymphatic Malformations: A Systematic Review.

BACKGROUND: Venolymphatic malformations are rare benign vascular lesions of the head and neck. Sclerotherapy has become the first-line therapy of these lesions with bleomycin being a sclerosing agent commonly used. PURPOSE: To perform a systematic review of the published literature to synthesize evidence on the safety and efficacy of bleomycin for the treatment of head and neck venolymphatic malformations. DATA SOURCES: A systematic review of the literature (January 1995-May 2019) was performed in PubMed, Embase, and Cochrane Library databases to identify studies on sclerotherapy of venolymphatic malformations of the head and neck. STUDY SELECTION: A total of 32 studies with participants met the inclusion criteria among which 1121 patients were included in the systematic review. DATA ANALYSIS: Two reviewers independently screened and extracted data and assessed the risk of bias. The primary outcome was the subjective or objective reduction of lesion size as well as minor and major complications. DATA SYNTHESIS: The bleomycin/pingyangmycin sclerotherapy achieved subjective or objective lesion size reduction in 96.3% (95% CI 94.1%-98.5%) of patients. Minor complications were observed in 16.2% and major complications in 1.1%. CONCLUSION: Bleomycin is a highly effective treatment of venolymphatic malformations of the head and neck with a low rate of major adverse events. This study represents an update on the "available" evidence, but only low-to-moderate quality studies were available. LIMITATIONS: This study reviewed 32 studies performed in different parts of the world, but there was heterogeneity of the study designs and interventions.

Admission Perfusion CT for Classifying Early In-Hospital Mortality of Patients With Severe Traumatic Brain Injury: A Pilot Study.

OBJECTIVE. The purposes of this study were to assess the feasibility and safety of perfusion CT of patients with severe traumatic brain injury (TBI) at hospital admission and to examine whether early in-hospital mortality could be characterized with perfusion CT (PCT). The hypothesis was that PCT can be used to characterize brain death, when present, in patients with severe TBI at hospital admission. SUBJECTS AND METHODS. In this prospective cohort pilot study, PCT was performed on patients with severe TBI at first imaging workup at hospital admission. PCT images were processed at the end of the study and assessed for features of brain death. The PCT features were then compared with the clinical outcome of in-hospital mortality. RESULTS. A total of 19 patients (13 men [68.4%]; six women [31.6%]; mean age, 36.4 years; median, 27.5 years) had a mean hospital stay longer than 1 month. No complications of PCT were found. In the first 48 hours after admission, four patients (21%) died. Admission PCT changes suggesting brainstem death were sensitive (75%) and specific (100%) and had high positive (100%) and negative (93.75%) predictive value for correct classification early in-hospital mortality. CONCLUSION. Admission PCT of patients with severe TBI was feasible and safe. Admission PCT findings helped in correctly classifying early in-hospital mortality in the first 48 hours of hospital admission.

Clinico-radiological correlation of magnetic resonance imaging findings in patients with idiopathic intracranial hypertension.

PURPOSE: Although several studies have reported imaging findings associated with idiopathic intracranial hypertension (IIH), less is known about the correlation between imaging findings and IIH-related symptoms or signs. Our study aimed to determine if clinical features of IIH are correlated with magnetic resonance imaging (MRI) features. METHODS: A retrospective chart review was conducted on consecutive patients presenting at the neuro-ophthalmology department over the last 15 years. All patients diagnosed with IIH were identified and those with available MRI were included in the final analysis. All MRI images were reviewed by a neuroradiologist blinded to the presenting symptoms and signs. Statistical analysis was performed to determine the correlation between the MRI findings with each clinical symptom or sign. RESULTS: Thirty-one out of 88 patients with the initial diagnosis of IIH had MRI available and were included in the study. Significant correlations were observed between colour vision and amount of perineural fluid around the optic nerve on MRI (r = - 0.382; p = 0.004), disc assessment and intraocular optic nerve protrusion (r = 0.364; p = 0.004), disc assessment and perineural fluid around the optic nerve (r = 0.276; p = 0.033) and disc assessment and venous sinus stenosis (r = 0.351; p = 0.009). CONCLUSION: Our study highlights correlations between imaging and clinical findings of IIH. MRI findings in IIH may be useful in ruling out ominous causes of intracranial pressure and risk stratifying ophthalmologic intervention and management of patients with headaches possibly due to IIH.

T2 Hypointensity Aids in the Diagnosis of Intracranial Metastatic Adenocarcinoma.

BACKGROUND: The T2 hypointensity has been suggested to be associated with intracranial metastatic adenocarcinomas (IMA). The purpose of our study was to determine the association of T2 hypointensity with IMA. METHODS: All patients with pathologically confirmed metastatic brain tumors who had a magnetic resonance imaging (MRI) at our institution in the last 10 years were retrospectively assessed. Qualitative assessment of the lesions on MRI was done by two separate readers who were blinded to the pathological diagnosis. For qualitative assessment, the T2 hypointensity in the lesion was compared with the contralateral normal appearing white matter. Odds ratio, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. RESULTS: Of 107 patients with intracranial metastasis, only 73 (40 females; 33 males; mean age 61 years) had MRI available for review. Of these, only 46 (25 females; 21 males; mean age 61 years) had pathologically proven IMA. T2 hypointensity was seen in 20% of IMA. The odds ratio of T2 hypointensity in IMA was 3 compared to nonadenocarcinomas but was not statistically significant (p = 0.16). Intralesional hemorrhage was seen in 20. When controlled for hemorrhage, the odds ratio for T2 hypointensity in IMA was 4.7. The specificity, sensitivity, PPV, and NPV for T2 hypointensity to diagnose IMA were 92%, 19%, 81%, and 40%, respectively. CONCLUSION: T2 hypointensity was seen only in 20% of IMA with an odds ratio of 4.7. T2 hypointensity showed a high specificity and PPV for diagnosis of IMA.

Diagnostic Yield of MRI for Sensorineural Hearing Loss - An Audit.

PURPOSE: Contrast-enhanced magnetic resonance imaging (CEMRI) of the head is frequently employed in investigations of sensorineural hearing loss (SNHL). The yield of these studies is perceptibly low and seemingly at odds with the aims of wise resource allocation and risk reduction within the Canadian healthcare system. The purpose of our study was to audit the use and diagnostic yield of CEMRI for the clinical indication of SNHL in our institution and to identify characteristics that may be leveraged to improve yield and optimize resource utilization. MATERIALS AND METHODS: The charts of 500 consecutive patients who underwent CEMRI of internal auditory canal for SNHL were categorized as cases with relevant positive findings on CEMRI and those without relevant findings. Demographics, presenting symptoms, interventions and responses, ordering physicians, and investigations performed prior to CEMRI testing were recorded. Chi-squared test and t-test were used to compare proportions and means, respectively. RESULTS: CEMRI studies revealed relevant findings in 20 (6.2%) of 324 subjects meeting the inclusion criteria. Pre-CEMRI testing beyond audiometry was conducted in 35% of those with relevant positive findings compared to 7.3% of those without (p < 0.001). Auditory brainstem response/vestibular-evoked myogenic potentials were abnormal in 35% of those with relevant CEMRI findings compared to 6.3% of those without (p < 0.001). CONCLUSION: CEMRI is a valuable tool for assessing potential causes of SNHL, but small diagnostic yield at present needs justification for contrast injection for this indication. Our findings suggest preferred referral from otolaryngologists exclusively, and implementation of a non-contrast MRI for SNHL may be a better diagnostic tool.

Endovascular Thrombectomy for Stroke Effectiveness Study-An Audit From a Small Tertiary Care Center.

PURPOSE: Endovascular thrombectomy (EVT) treatment for acute ischemic stroke is now recommended as a standard of care. However, implementing EVT in routine clinical practice poses many challenges, even in countries with advanced health-care systems. The aim of the current study is to delineate if EVT at our institution is an effective treatment for acute ischemic stroke. METHODS: All patients who underwent EVT at our institution between December 2011 and July 2017 were retrospectively assessed from our prospective registry. Clinical and imaging (including the Alberta Stroke Program Early CT [ASPECT] score, single-phase computed tomography angiography, and computed tomography perfusion) criteria were utilized to determine EVT suitability. Primary outcomes included modified Rankin score (mRS) at 90 days and recanalization determined by the modified Treatment in Cerebral Infarction score. Effectiveness was assessed by comparing our cohort with patients receiving EVT in the ESCAPE (Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke) trial. RESULTS: Eighty-eight patients presented to our hospital after a median of 87 minutes last seen normal. Of these, median ASPECT score was 9. A majority (72%) also received intravenous alteplase. Successful recanalization (≥TICI 2b) was achieved in 79%. At 90 days, 48% (36/75) were functionally independent (mRS score of 0-2) and 28% (21/75) were disabled (mRS score of 3-5); 24% (18/75) died (mRS of 6) within 90 days. CONCLUSIONS: An audit of our initial experience with EVT for the treatment of acute ischemic stroke in a small tertiary care center yielded similar results compared to the ESCAPE trial, which is encouraging for implementing this treatment in routine clinical practice.

Imaging Improves Efficacy of Vertebroplasty - A Systematic Review and Meta-Analysis.

BACKGROUND: Clinical trials with percutaneous vertebral augmentation (PVA) for intractable pain from vertebral compression fractures (VCF) have shown variable results. Variation in the outcomes may be related to poor patient selection on imaging. OBJECTIVE: To assess if PVA augmentation for osteoporotic VCF results in better improvement in pain when patients were selected based on clinical examination plus imaging vs clinical examination only. RESULTS: A systematic review and meta-analysis were performed. PubMed, Embase and Cochrane Library databases were searched from 2000 to May 2018. Two reviewers independently screened and extracted data to identify randomised control trials (RCTs) on PVA for osteoporotic VCF and assessed the risk of bias. Standard systematic review and meta-analysis methods were advocated by the Cochrane Collaboration and PRISMA Statement. A total of 12 RCTs with 1110 participants met the inclusion criteria. Eight of the 10 studies (938 participants) that used imaging to confirm oedema in the target vertebral bodies showed PVA (compared to nonsurgical treatment) was effective in reducing pain (immediate term: mean difference (MD) of -1.89; 95% confidence interval -1.93 to -1.85, p < 0.001; short term: MD of -1.68; 95% CI -1.82 to -1.54, p < 0.001; intermediate term: MD of -2.04; 95% CI -2.15 to -1.94, p < 0.001 and long term: MD of -1.88; 95% CI -1.95 to -1.80, p < 0.001). CONCLUSIONS: RCTs using imaging to confirm marrow oedema in the index vertebra showed an improved size effect compared to RCTs using no imaging. This benefit was observed in the immediate, short, intermediate and long term.

Améliorer l'efficacité de la vertébroplastie au moyen de l'imagerie médicale : une revue systématique et une méta-analyse.Contexte: Des essais cliniques au cours desquels on a fait appel aux techniques percutanées de la vertébroplastie (vertebral augmentation) pour soulager des douleurs réfractaires produites par des fractures vertébrales par compression (FVC) ont donné à voir des résultats variables. Cette variabilité pourrait être liée à une mauvaise sélection des participants au moyen d'examens d'IRM. Objectif: Évaluer dans quelle mesure la vertébroplastie entraîne un soulagement accru de la douleur dans le cas de patients aux prises avec des FVC d'origine ostéoporotique. On a ainsi voulu comparer des patients choisis en fonction d'un examen clinique et d'un examen d'IRM avec d'autres patients choisis en fonction d'un seul examen clinique. Résultats: Nous avons mené une revue systématique ainsi qu'une méta-analyse. Pour ce faire, nous avons effectué des recherches dans les bases de données suivantes : PubMed, Embase et Cochrane, et ce, de l'année 2000 au mois de mai 2018. Deux examinateurs indépendants ont ensuite extrait et passé au crible des données afin d'identifier les essais cliniques randomisés (ECR) portant sur la vertébroplastie dans le cas de FVC d'origine ostéoporotique et d'évaluer les risques de biais. À noter que notre revue systématique et notre méta-analyse ont été effectuées en tenant compte des méthodes recommandées par Cochrane et PRISMA. Au total, douze ECR incluant 1110 participants ont satisfait à nos critères de sélection. Sur 10 ECR (938 participants) dans lesquels on a recouru à un examen d'IRM pour confirmer la présence d'un œdème dans les corps vertébraux ciblés, 8 d'entre eux ont révélé que le recours à la vertébroplastie était plus efficace qu'un traitement non-chirurgical dans le soulagement de la douleur (sur le champ : écart moyen de -1,89 ; IC 95 % -1,93 à -1,85 ; p < 0,001 ; à court terme : écart moyen de -1,68 ; IC 95 % -1,82 à -1,54 ; p < 0,001 ; à moyen terme : écart moyen de -2,04 ; IC 95 % -2,15 à -1,94 ; p < 0,001 ; et à long terme : écart moyen de -1,88 ; IC 95% -1,95 à -1,80 ; p < 0,001). Conclusions: En somme, les ECR utilisant des examens d'IRM pour confirmer la présence d'œdèmes de la moelle épinière dans une vertèbre de référence (index vertebra) ont révélé une taille d'effet améliorée si on les compare à des ECR n'utilisant pas ces examens. Cet avantage a été observé sur le champ mais aussi à court, moyen et long terme.

Diffusion weighted imaging may help differentiate intracranial hemangiopericytoma from meningioma.

BACKGROUND AND PURPOSE: Hemangiopericytoma and meningioma appear similar on routine diagnostic imaging and hence are difficult to distinguish. The purpose of our study was to examine the diffusion weighted imaging (DWI) characteristics of these two types of tumours. METHODS: In a retrospective study, each patient with hemangiopericytoma was matched with two meningioma patients based on tumour location and size. Minimum and mean apparent diffusion coefficients (ADC) were measured in the tumour and the contralateral normal-appearing white matter (NAWM). A normalized ADC was calculated. The two tumour types were subjectively assessed for heterogeneity on ADC maps. RESULTS: Of the 14 patients with histopathological proven hemangiopericytoma, only 7 had available DWI for analysis. These 7 patients were matched based on tumour location and size with 14 patients out of the 209 meningioma patients screened. Hemangiopericytomas were more heterogeneous on ADC maps (P < 0.001) and had a higher mean ADC compared to that of meningiomas (P < 0.001). CONCLUSION: Hemangiopericytomas showed heterogeneity on DWI and significantly higher ADC compared to that of meningiomas in our small study. These observations need to be confirmed in future studies with larger sample sizes.

Use of Noncontrast Computed Tomography and Computed Tomographic Perfusion in Predicting Intracerebral Hemorrhage After Intravenous Alteplase Therapy.

BACKGROUND AND PURPOSE: Intracerebral hemorrhage is a feared complication of intravenous alteplase therapy in patients with acute ischemic stroke. We explore the use of multimodal computed tomography in predicting this complication. METHODS: All patients were administered intravenous alteplase with/without intra-arterial therapy. An age- and sex-matched case-control design with classic and conditional logistic regression techniques was chosen for analyses. Outcome was parenchymal hemorrhage on 24- to 48-hour imaging. Exposure variables were imaging (noncontrast computed tomography hypoattenuation degree, relative volume of very low cerebral blood volume, relative volume of cerebral blood flow ≤7 mL/min·per 100 g, relative volume of Tmax ≥16 s with all volumes standardized to z axis coverage, mean permeability surface area product values within Tmax ≥8 s volume, and mean permeability surface area product values within ipsilesional hemisphere) and clinical variables (NIHSS [National Institutes of Health Stroke Scale], onset to imaging time, baseline systolic blood pressure, blood glucose, serum creatinine, treatment type, and reperfusion status). RESULTS: One-hundred eighteen subjects (22 patients with parenchymal hemorrhage versus 96 without, median baseline NIHSS score of 15) were included in the final analysis. In multivariable regression, noncontrast computed tomography hypoattenuation grade (P<0.006) and computerized tomography perfusion white matter relative volume of very low cerebral blood volume (P=0.04) were the only significant variables associated with parenchymal hemorrhage on follow-up imaging (area under the curve, 0.73; 95% confidence interval, 0.63-0.83). Interrater reliability for noncontrast computed tomography hypoattenuation grade was moderate (κ=0.6). CONCLUSIONS: Baseline hypoattenuation on noncontrast computed tomography and very low cerebral blood volume on computerized tomography perfusion are associated with development of parenchymal hemorrhage in patients with acute ischemic stroke receiving intravenous alteplase.

Regional Comparison of Multiphase Computed Tomographic Angiography and Computed Tomographic Perfusion for Prediction of Tissue Fate in Ischemic Stroke.

BACKGROUND AND PURPOSE: Within different brain regions, we determine the comparative value of multiphase computed tomographic angiography (mCTA) and computed tomographic perfusion (CTP) in predicting follow-up infarction. METHODS: Patients with M1-middle cerebral artery occlusions were prospectively included in this multicenter study. Regional analysis was performed for each patient within Alberta Stroke Program Early CT Score regions M2 to M6. Regional pial vessel filling was assessed on mCTA in 3 ways: (1) Washout of contrast within pial vessels; (2) Extent of maximal pial vessel enhancement compared with contralateral hemisphere; (3) Delay in maximal pial vessel enhancement compared with contralateral hemisphere. Cerebral blood flow, cerebral blood volume, and Tmax data were extracted within these Alberta Stroke Program Early CT Score regions. Twenty-four- to 36-hour magnetic resonance imaging/CT was assessed for infarct in each Alberta Stroke Program Early CT Score region (defined as >20% infarction within that region). Mixed effects logistic regression models were used to compare mCTA and CTP parameters when predicting brain infarction. Area under the receiver operating characteristics was used to assess discriminative value of statistical models. RESULTS: Seventy-seven patients were included. mCTA parameter washout and CTP parameter Tmax were significantly associated with follow-up infarction in all models (P<0.05). The area under the receiver operating characteristic for mCTA models ranged from 92% to 94% and was not different compared with all CTP models (P>0.05). Mean Tmax and cerebral blood volume values were significantly different between each washout score (P<0.01) and each delay score category (P<0.01). Mean Tmax, cerebral blood flow, and cerebral blood volume values were significantly different between each extent score category (P<0.05). CONCLUSIONS: Similar to CTP, multiphase CTA can be used to predict tissue fate regionally in acute ischemic stroke patients.

CT Perfusion in Acute Stroke Predicts Final Infarct Volume- Inter-observer Study.

BACKGROUND: Computed tomography perfusion (CTP) is increasingly being used in the setting of acute ischemic stroke (AIS). The aim of the current study was to compare the prognostic utility of, and inter-observer variation between, baseline appearances on non-contrast CT (using Alberta Stroke Program Early CT score(ASPECTS)) and on CTP for predicting final infarct volume. We also assessed impact of training on interpretation of these images. METHODS: Retrospectively, plain head computed tomography (CT) and CTP images at presentation and CT or diffusion imaging on follow up of patients with AIS were analyzed. The lesion volume on different CTP parameters was then correlated with the final infarct volume. This analysis was done by a Neuroradiologist, a stroke Neurologist and a medical student. Kappa statistics and Intra-class correlation coefficients were used for agreement between readers. Pearson correlation coefficients were used. RESULTS: Thirty eight patients with AIS met all inclusion criteria. There was very good agreement among all readers for the CTP parameters. There was only fair agreement for ASPECT score. Correlation coefficient (r-square) between CTP parameters and final infarct volume showed that cerebral blood volume was the best parameter to predict the final infarct volume followed by cerebral blood flow and time to peak. The best reader to predict the final infarct volume on the initial CT perfusion study was the neuroradiologist followed by medical student and stroke neurologist. CONCLUSIONS: Cerebral blood volume defect correlated the best with the final infarct volume. There was a very good inter-observer agreement for all the CTP maps in predicting the final infarct volume despite the wide variation in the experience of the readers.

Normalized Apparent Diffusion Coefficient in the Prognostication of Patients with Glioblastoma Multiforme.

BACKGROUND: Glioblastoma multiforme (GBM) is known to have poor prognosis, with no available imaging marker that can predict survival at the time of diagnosis. Diffusion weighted images are used in characterisation of cellularity and necrosis of GBM. The purpose of this study was to assess whether pattern or degree of diffusion restriction could help in the prognostication of patients with GBM. MATERIAL AND METHODS: We retrospectively analyzed 84 consecutive patients with confirmed GBM on biopsy or resection. The study was approved by the institutional ethics committee. The total volume of the tumor and total volume of tumor showing restricted diffusion were calculated. The lowest Apparent Diffusion Coefficient (ADC) in the region of the tumor and in the contralateral Normal Appearing White Matter were calculated in order to calculate the nADC. Treatment and follow-up data in these patients were recorded. Multivariate analsysis was completed to determine significant correlations between different variables and the survival of these patients. RESULTS: Patient survival was significantly related to the age of the patient (p<0.0001; 95% CI-1.022-1.043) and the nADC value (p=0.014; 95% CI-0.269-0.860) in the tumor. The correlation coefficients of age and nADC with survival were -0.335 (p=0.002) and 0.390 (p<0.001), respectively. Kaplan Meier survival function, grouped by normalized Apparent Diffusion Coefficient cut off value of 0.75, was significant (p=0.007). CONCLUSION: The survival of patients with GBM had small, but significant, correlations with the patient's age and nADC within the tumor.

Diagnosing Vasospasm After Subarachnoid Hemorrhage: CTA and CTP.

Cerebral vasospasm is a potentially devastating complication in patients with aneurysmal subarachnoid hemorrhage. The purpose of this article is to review the use of computed tomogram (CT) angiography and CT perfusion in the diagnosis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage and also assess their use in guiding treatment decisions. Both techniques are widely used for other indications but their use in cerebral vasospasm has not been well defined. Computed tomogram angiography can directly visualize arterial narrowing and CT perfusion is able to evaluate differences in perfusion parameters after aneurysmal subarachnoid hemorrhage with high sensitivity and specificity. CT perfusion is better at predicting which patients require endovascular treatment.

Iterative Reconstruction for Head CT: Effects on Radiation Dose and Image Quality.

BACKGROUND: Iterative reconstruction has been reported to reduce radiation dose in CT, while preserving and even improving image quality. The purpose of this study was to evaluate the effects of sinogram-affirmed iterative reconstruction (SAFIRE) on radiation dose reduction and image quality for noncontrast adult head CT and to compare SAFIRE with conventional filtered back-projection (FBP) reconstruction. METHODS: Institutional review board approval was obtained for this retrospective analysis of head CT scans reconstructed with SAFIRE and/or FBP for 107 patients. Radiation dose parameters were recorded from scanner-generated CT dose reports. Signal-to-noise and contrast-to-noise ratios (SNR, CNR) were calculated from gray and white matter (GM, WM) attenuation measurements. Image noise, artifacts, GM-WM differentiation, small structure visibility, and sharpness were graded by two readers. Statistical analysis included the independent-samples t test for quantitative data, the related samples Wilcoxon signed-rank test for qualitative data, the coefficient of repeatability for intraobserver variation, and κ statistics for interobserver agreement. RESULTS: Mean effective dose was significantly reduced with SAFIRE from 2.0 to 1.7 mSv (p<0.0001). SAFIRE also significantly improved GM SNR, WM SNR, and GM-WM CNR (p<0.0001). Significant reductions in image noise and posterior fossa artifact as well as improvements in GM-WM differentiation, small structure visibility, and sharpness were noted with SAFIRE (P<0.005). CONCLUSIONS: SAFIRE for noncontrast adult head CT reduces patient radiation dose by 15% for the settings employed at our institution, while significantly improving multiple quantitative and qualitative measures of image quality.

Evaluation of perfusion CT in grading and prognostication of high-grade gliomas at diagnosis: a pilot study.

OBJECTIVE: Differentiation of grade 3 astrocytoma from glioblastoma multiforme can be difficult with conventional structural imaging but is important for prognosis. The purpose of this study was to assess perfusion CT in differentiating high-grade gliomas (HGGs) and their role in prognosis in the care of patients with HGG. SUBJECTS AND METHODS: Twenty patients with previously untreated HGG underwent prospective evaluation with perfusion CT. Permeability surface area product (PS) and cerebral blood volume (CBV) were calculated by the deconvolution method and were compared between HGGs with Student two-sample t tests. Receiver operating characteristic curves were generated for PS, CBV, and the conjoint factor PS + CBV. Cox regression analysis was used to correlate these parameters with patient survival over a follow-up period. Hazard ratios were calculated, and Kaplan-Meier survival curves were drawn. RESULTS: There was a significant difference between grade 3 and grade 4 gliomas for PS (p = 0.022) and PS + CBV (p = 0.019) but not for CBV alone (p = 0.411). Receiver operating characteristic analyses showed that PS (area under the curve [AUC], 0.72) and CBV + PS (AUC, 0.73) can be used to differentiate grade 3 from grade 4 gliomas but that CBV alone cannot be so used (AUC, 0.54). There was a significant relation between patient outcome and age (p = 0.034) and CBV + PS (p = 0.048). Patients with HGG and a CBV + PS greater than 9 had a poor outcome (hazard ratio, 6.00). CONCLUSION: PS and CBV + PS can be used to differentiate grade 3 from grade 4 gliomas. The outcome of patients with HGG depends on age and CBV + PS.