Impact of Deep Learning Image Reconstruction Methods on MRI Throughput

Purpose To evaluate the effect of implementing two distinct commercially available deep learning reconstruction (DLR) algorithms on the efficiency of MRI examinations conducted in real clinical practice within an outpatient setting at a large, multicenter institution. Materials and Methods This retrospective study included 7346 examinations from 10 clinical MRI scanners analyzed during the pre- and postimplementation periods of DLR methods. Two different types of DLR methods, namely Digital Imaging and Communications in Medicine (DICOM)-based and k-space-based methods, were implemented in half of the scanners (three DICOM-based and two k-space-based), while the remaining five scanners had no DLR method implemented. Scan and room times of each examination type during the pre- and postimplementation periods were compared among the different DLR methods using the Wilcoxon test. Results The application of deep learning methods resulted in significant reductions in scan and room times for certain examination types. The DICOM-based method demonstrated up to a 53% reduction in scan times and a 41% reduction in room times for various study types. The k-space-based method demonstrated up to a 27% reduction in scan times but did not significantly reduce room times. Conclusion DLR methods were associated with reductions in scan and room times in a clinical setting, though the effects were heterogeneous depending on examination type. Thus, potential adopters should carefully evaluate their case mix to determine the impact of integrating these tools. Keywords: Deep Learning MRI Reconstruction, Reconstruction Algorithms, DICOM-based Reconstruction, k-Space-based Reconstruction © RSNA, 2024 See also the commentary by GharehMohammadi in this issue.

Academic Neuroradiology: 2023 Update on Turn-Around Time, Financial Recruitment and Retention Strategies

The ASNR Neuroradiology Division Chief Working Group's 2023 survey, with responses from 62 division chiefs, provides insights into turn-around times, faculty recruitment, moonlighting opportunities, and academic funds.In emergency cases, 61% aim for a turn-around time of less than 45-60 minutes, with two-thirds meeting this expectation more than 75% of the time. For inpatient CT and MRI scans, 54% achieve a turn-around time of 4-8 hours, with three quarters meeting this expectation at least 50% of the time. Outpatient scans have an expected turn-around time of 24-48 hours, which is met in 50% of cases.Faculty recruitment strategies included 35% offering sign-on bonuses, with a median of $30,000. Additionally, 23% provided bonuses to fellows during fellowship to retain them in the practice upon completion of their fellowship. Internal moonlighting opportunities for faculty were offered by 70% of divisions, with a median pay of $250 per hour.The median annual academic fund for a full-time neuroradiology faculty member was $6,000, typically excluding license fees but including ACR and ABR membership, leaving $4,000 for professional expenses.This survey calls for further dialogue on adapting and innovating academic institutions to meet evolving needs in neuroradiology.

Automated assessment of ischemic core on non-contrast computed tomography: a multicenter comparative analysis with CT perfusion

BACKGROUND

Application of machine learning (ML) algorithms has shown promising results in estimating ischemic core volumes using non-contrast CT (NCCT).

OBJECTIVE

To assess the performance of the e-Stroke Suite software (Brainomix) in assessing ischemic core volumes on NCCT compared with CT perfusion (CTP) in patients with acute ischemic stroke.

METHODS

In this retrospective multicenter study, patients with anterior circulation large vessel occlusions who underwent pretreatment NCCT and CTP, successful reperfusion (modified Thrombolysis in Cerbral Infarction ≥2b), and post-treatment MRI, were included from three stroke centers. Automated calculation of ischemic core volumes was obtained on NCCT scans using ML algorithm deployed by e-Stroke Suite and from CTP using Olea software (Olea Medical). Comparative analysis was performed between estimated core volumes on NCCT and CTP and against MRI calculated final infarct volume (FIV).

RESULTS

A total of 111 patients were included. Estimated ischemic core volumes (mean±SD, mL) were 20.4±19.0 on NCCT and 19.9±18.6 on CTP, not significantly different (P=0.82). There was moderate (r=0.40) and significant (P<0.001) correlation between estimated core on NCCT and CTP. The mean difference between FIV and estimated core volume on NCCT and CTP was 29.9±34.6 mL and 29.6±35.0 mL, respectively (P=0.94). Correlations between FIV and estimated core volume were similar for NCCT (r=0.30, P=0.001) and CTP (r=0.36, P<0.001).

CONCLUSIONS

Results show that ML-based estimated ischemic core volumes on NCCT are comparable to those obtained from concurrent CTP in magnitude and in degree of correlation with MR-assessed FIV.

Differential Subsampling with Cartesian Ordering-MRA for Classifying Residual Treated Aneurysms

BACKGROUND AND PURPOSE

Differential Subsampling with Cartesian Ordering (DISCO), an ultrafast high-spatial-resolution head MRA, has been introduced. We aimed to determine the diagnostic performance of DISCO-MRA in grading residual aneurysm in comparison with TOF-MRA in patients with treated intracranial aneurysms.

MATERIALS AND METHODS

Patients with endovascular treatment and having undergone DISCO-MRA, TOF-MRA, and DSA were included for review. The voxel size and acquisition time were 0.75 × 0.75 × 1 mm³/6 seconds for DISCO-MRA and 0.6 × 0.6 × 1 mm³/6 minutes for TOF-MRA. Residual aneurysms were determined using the Modified Raymond-Roy Classification on TOF-MRA and DISCO-MRA by 2 neuroradiologists independently and were compared against DSA as the reference standard. Statistical analysis was performed using the κ statistic and the χ² test.

RESULTS

Sixty-eight treated intracranial aneurysms were included. The intermodality agreement was κ = 0.82 (95% CI, 0.67-0.97) between DISCO and DSA and 0.44 (95% CI, 0.28-0.61) between TOF and DSA. Modified Raymond-Roy Classification scores matched DSA scores in 60/68 cases (88%; χ² = 144.4, P < .001 for DISCO and 46/68 cases (68%; χ² = 65.0, P < .001) for TOF. The diagnostic accuracy for the detection of aneurysm remnants was higher for DISCO (0.96; 95% CI, 0.88-0.99) than for TOF (0.79; 95% CI, 0.68-0.88).

CONCLUSIONS

In patients with endovascularly treated intracranial aneurysms, DISCO-MRA provides superior diagnostic performance in comparison with TOF-MRA in delineating residual aneurysms in a fraction of the time.

Deep Learning Automates Measurement of Spinopelvic Parameters on Lateral Lumbar Radiographs

STUDY DESIGN

Cross-sectional database study.

OBJECTIVE

The objective of this study was to develop an algorithm for the automated measurement of spinopelvic parameters on lateral lumbar radiographs with comparable accuracy to surgeons.

SUMMARY OF BACKGROUND DATA

Sagittal alignment measurements are important for the evaluation of spinal disorders. Manual measurement methods are time-consuming and subject to rater-dependent error. Thus, a need exists to develop automated methods for obtaining sagittal measurements. Previous studies of automated measurement have been limited in accuracy, inapplicable to common plain films, or unable to measure pelvic parameters.

METHODS

Images from 816 patients receiving lateral lumbar radiographs were collected sequentially and used to develop a convolutional neural network (CNN) segmentation algorithm. A total of 653 (80%) of these radiographs were used to train and validate the CNN. This CNN was combined with a computer vision algorithm to create a pipeline for the fully automated measurement of spinopelvic parameters from lateral lumbar radiographs. The remaining 163 (20%) of radiographs were used to test this pipeline. Forty radiographs were selected from the test set and manually measured by three surgeons for comparison.

RESULTS

The CNN achieved an area under the receiver-operating curve of 0.956. Algorithm measurements of L1-S1 cobb angle, pelvic incidence, pelvic tilt, and sacral slope were not significantly different from surgeon measurement. In comparison to criterion standard measurement, the algorithm performed with a similar mean absolute difference to spine surgeons for L1-S1 Cobb angle (4.30° ± 4.14° vs. 4.99° ± 5.34°), pelvic tilt (2.14° ± 6.29° vs. 1.58° ± 5.97°), pelvic incidence (4.56° ± 5.40° vs. 3.74° ± 2.89°), and sacral slope (4.76° ± 6.93° vs. 4.75° ± 5.71°).

CONCLUSION

This algorithm measures spinopelvic parameters on lateral lumbar radiographs with comparable accuracy to surgeons. The algorithm could be used to streamline clinical workflow or perform large scale studies of spinopelvic parameters.Level of Evidence: 3.

Sources of Revenue Loss and Recovery in Radiology Practices During the Coronavirus Disease 2019 (COVID-19) Pandemic

Rationale and Objectives

This study seeks to quantify the financial impact of COVID-19 on radiology departments, and to describe the structure of both volume and revenue recovery.

Materials and Methods

Radiology studies from a large academic health system were retrospectively studied from the first 33 weeks of 2020. Volume and work relative value unit (wRVU) data were aggregated on a weekly basis for three periods: Presurge (weeks 1–9), surge (10–19), and recovery (20–33), and analyzed compared to the pre-COVID baseline stratified by modality, specialty, patient service location, and facility type. Mean and median wRVU per study were used as a surrogate for case complexity.

Results

During the pandemic surge, case volumes fell 57%, while wRVUs fell by 69% relative to the pre-COVID-19 baseline. Mean wRVU per study was 1.13 in the presurge period, 1.03 during the surge, and 1.19 in the recovery. Categories with the greatest mean complexity declines were radiography (−14.7%), cardiothoracic imaging (−16.2%), and community hospitals overall (−15.9%). Breast imaging (+6.5%), interventional (+5.5%), and outpatient (+12.1%) complexity increased. During the recovery, significant increases in complexity were seen in cardiothoracic (0.46 to 0.49), abdominal (1.80 to 1.91), and neuroradiology (2.46 to 2.56) at stand-alone outpatient centers with similar changes at community hospitals. At academic hospitals, only breast imaging complexity remained elevated (1.32 from 1.17) during the recovery.

Conclusion

Reliance on volume alone underestimates the financial impact of the COVID-19 pandemic as there was a disproportionate loss in high-RVU studies. However, increased complexity of outpatient cases has stabilized overall losses during the recovery.

Impact of COVID-19 social distancing regulations on outpatient diagnostic imaging volumes and no-show rates

Background

The coronavirus disease 2019 (COVID-19) pandemic has significantly impacted outpatient radiology practices, necessitating change in practice infrastructure and workflow.

Objective

The purpose of this study was to assess the consequences of social distancing regulations on 1) outpatient imaging volume and 2) no-show rates per imaging modality.

Methods

Volume and no-show rates of a large, multicenter metropolitan healthcare system outpatient practice were retrospectively stratified by modality including radiography, CT, MRI, ultrasonography, PET, DEXA, and mammography from January 2 to July 21, 2020. Trends were assessed relative to timepoints of significant state and local social distancing regulatory changes.

Results

The decline in imaging volume and rise in no-show rates was first noted on March 10, 2020 following the declaration of a state of emergency in New York State (NYS). Total outpatient imaging volume declined 85% from baseline over the following 5 days. Decreases varied by modality: 88% for radiography, 75% for CT, 73% for MR, 61% for PET, 80% for ultrasonography, 90% for DEXA, and 85% for mammography. Imaging volume and no-show rate recovery preceded the mask mandate of April 15, 2020, and further trended along with New York City's reopening phases. No-show rates recovered within 2 months of the height of the pandemic, however, outpatient imaging volume has yet to recover to baseline after 3 months.

Conclusion

The total outpatient imaging volume declined alongside an increase in the no-show rate following the declaration of a state of emergency in NYS. No-show rates recovered within 2 months of the height of the pandemic with imaging volume yet to recover after 3 months.

Clinical impact

Understanding the impact of social distancing regulations on outpatient imaging volume and no-show rates can potentially aid other outpatient radiology practices and healthcare systems in anticipating upcoming changes as the COVID-19 pandemic evolves.

Neurovascular complications that can be seen in COVID-19 patients

Coronavirus disease 2019 (COVID-19), a clinical manifestation of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was declared a global pandemic by the World Health Organization on March 11, 2020. Hypercoagulable state has been described as one of the hallmarks of SARS-CoV-2 infection and has been reported to manifest as pulmonary embolisms, deep vein thrombosis, and arterial thrombosis of the abdominal small vessels. Here we present cases of arterial and venous thrombosis pertaining to the head and neck in COVID-19 patients.

Infundibulum at the origin of an accessory middle cerebral artery

We present a case of an infundibular dilation at the origin of an accessory middle cerebral artery emanating from the distal A1 segment of the anterior cerebral artery. There was also partial vessel wall enhancement along this infundibulum. To our knowledge, this is the first case report with such findings.

Multidisciplinary management of metastatic spine disease: initial symptom-directed management

In the past 2 decades, a deeper understanding of the cancer molecular signature has resulted in longer longevity of cancer patients, hence a greater population, who potentially can develop metastatic disease. Spine metastases (SM) occur in up to 70% of cancer patients. Familiarizing ourselves with the key aspects of initial symptom-directed management is important to provide SM patients with the best patient-specific options. We will review key components of initial symptoms assessment such as pain, neurological symptoms, and spine stability. Radiographic evaluation of SM and its role in management will be reviewed. Nonsurgical treatment options are also presented and discussed, including percutaneous procedures, radiation, radiosurgery, and spine stereotactic body radiotherapy. The efforts of a multidisciplinary team will continue to ensure the best patient care as the landscape of cancer is constantly changing.

Imaging Features of Acute Encephalopathy in Patients with COVID-19: A Case Series

Coronavirus disease 2019 was declared a global pandemic by the World Health Organization on March 11, 2020. There is a scarcity of data on coronavirus disease 2019-related brain imaging features. We present 5 cases that illustrate varying imaging presentations of acute encephalopathy in patients with coronavirus disease 2019. MR features include leukoencephalopathy, diffusion restriction that involves the GM and WM, microhemorrhages, and leptomeningitis. We believe it is important for radiologists to be familiar with the neuroradiologic imaging spectrum of acute encephalopathy in the coronavirus disease 2019 population.

COVID-19 Is an Independent Risk Factor for Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Coronavirus disease 2019 (COVID-19) is an active worldwide pandemic with diverse complications. Stroke as a presentation has not been strongly associated with COVID-19. The authors aimed to retrospectively review a link between COVID-19 and acute stroke.

MATERIALS AND METHODS

We conducted a retrospective case-control study of 41 cases and 82 control subjects matched by age, sex, and risk factors. Cases were patients who underwent stroke alert imaging with confirmed acute stroke on imaging between March 16 and April 5, 2020, at 6 hospitals across New York City. Control subjects were those who underwent stroke alertimaging during the same timeframe without imaging evidence of acute infarction. Data pertaining to diagnosis of COVID-19 infection, patient demographics, and risk factors were collected. A univariate analysis was performed to assess the covariate effect of risk factors and COVID-19 status on stroke imaging with positive findings.

RESULTS

The mean age for cases and controls was 65.5 ± 15.3 years and 68.8 ± 13.2 years, respectively. Of patients with acute ischemic stroke, 46.3% had COVID-19 infection compared with 18.3% of controls (P = .001). After adjusting for age, sex, and risk factors, COVID-19 infection had a significant independent association with acute ischemic stroke compared with control subjects (OR, 3.9; 95% CI, 1.7-8.9; P = .001).

CONCLUSIONS

We demonstrated that COVID-19 infection is significantly associated with imaging confirmation of acute ischemic stroke, and patients with COVID-19 should undergo more aggressive monitoring for stroke.

Combination of Imaging Features and Clinical Biomarkers Predicts Positive Pathology and Microbiology Findings Suggestive of Spondylodiscitis in Patients Undergoing Image-Guided Percutaneous Biopsy

BACKGROUND AND PURPOSE

Pathology and microbiology results for suspected spondylodiscitis on MR imaging are often negative in up to 70% of cases. We aimed to predict whether MR imaging features will add diagnostic value when combined with clinical biomarkers to predict positive findings of spondylodiscitis on pathology and/or microbiology from percutaneous biopsy.

MATERIALS AND METHODS

In this retrospective single-center institutional review board-approved study, patients with radiologically suspected spondylodiscitis and having undergone percutaneous biopsies were assessed. Demographic characteristics, laboratory values, and tissue and blood cultures were collected. Pathology and microbiology results were used as end points. Three independent observers provided MR imaging-based scoring for typical MR imaging features for spondylodiscitis. Multivariate logistic regression and receiver operating characteristic analysis were performed to determine an optimal combination of imaging and clinical biomarkers in predicting positive findings on pathology and/or microbiology from percutaneous biopsy suggestive of spondylodiscitis.

RESULTS

Our patient cohort consisted of 72 patients, of whom 33.3% (24/72) had spondylodiscitis. The mean age was 63 ± 16 years with a male/female ratio of 41:31. Logistic regression revealed a combination with an area under the curve of 0.72 for pathology and 0.68 for pathology and/or microbiology. Epidural enhancement on MR imaging improved predictive performance to 0.87 for pathology and 0.78 for pathology and/or microbiology.

CONCLUSIONS

Our findings demonstrate that epidural enhancement on MR imaging added diagnostic value when combined with clinical biomarkers to help predict which patients undergoing percutaneous biopsy will have positive findings for spondylodiscitis on pathology and/or microbiology.

Estimation of Ischemic Core Volume Using Computed Tomographic Perfusion

Background and Purpose- Estimation of infarction based on computed tomographic perfusion (CTP) has been challenging, mainly because of noise associated with CTP data. The Bayesian method is a robust probabilistic method that minimizes effects of oscillation, tracer delay, and noise during residue function estimation compared with other deconvolution methods. This study compares CTP-estimated ischemic core volume calculated by the Bayesian method and by the commonly used block-circulant singular value deconvolution technique. Methods- Patients were included if they had (1) anterior circulation ischemic stroke, (2) baseline CTP, (3) successful recanalization defined by thrombolysis in cerebral infarction ≥IIb, and (4) minimum infarction volume of >5 mL on follow-up magnetic resonance imaging (MRI). CTP data were processed with circulant singular value deconvolution and Bayesian methods. Two established CTP methods for estimation of ischemic core volume were applied: cerebral blood flow (CBF) method (relative CBF, <30% within the region of delay >2 seconds) and cerebral blood volume method (<2 mL per 100 g within the region of relative mean transit time >145%). Final infarct volume was determined on MRI (fluid-attenuated inversion recovery images). CTP and MRI-derived ischemic core volumes were compared by univariate and Bland-Altman analysis. Results- Among 35 patients included, the mean/median (mL) difference for CTP-estimated ischemic core volume against MRI was -4/-7 for Bayesian CBF ( P=0.770), 20/12 for Bayesian cerebral blood volume ( P=0.041), 21/10 for circulant singular value deconvolution CBF ( P=0.006), and 35/18 for circulant singular value deconvolution cerebral blood volume ( P<0.001). Among all methods, Bayesian CBF provided the narrowest limits of agreement (-28 to 19 mL) in comparison with MRI. Conclusions- Despite existing variabilities between CTP postprocessing methods, Bayesian postprocessing increases accuracy and limits variability in CTP estimation of ischemic core.

Defining Ischemic Core in Acute Ischemic Stroke Using CT Perfusion: A Multiparametric Bayesian-Based Model

BACKGROUND AND PURPOSE

The Bayesian probabilistic method has shown promising results to offset noise-related variability in perfusion analysis. Using CTP, we aimed to find optimal Bayesian-estimated thresholds based on multiparametric voxel-level models to estimate the ischemic core in patients with acute ischemic stroke.

MATERIALS AND METHODS

Patients with anterior circulation acute ischemic stroke who had baseline CTP and achieved successful recanalization were included. In a subset of patients, multiparametric voxel-based models were constructed between Bayesian-processed CTP maps and follow-up MRIs to identify pretreatment CTP parameters that were predictive of infarction using robust logistic regression. Subsequently CTP-estimated ischemic core volumes from our Bayesian model were compared against routine clinical practice oscillation singular value decomposition-relative cerebral blood flow <30%, and the volumetric accuracy was assessed against final infarct volume.

RESULTS

In the constructed multivariate voxel-based model, 4 variables were identified as independent predictors of infarction: TTP, relative CBF, differential arterial tissue delay, and differential mean transit time. At an optimal cutoff point of 0.109, this model identified infarcted voxels with nearly 80% accuracy. The limits of agreement between CTP-estimated ischemic core and final infarct volume ranged from -25 to 27 mL for the Bayesian model, compared with -61 to 52 mL for oscillation singular value decomposition-relative CBF.

CONCLUSIONS

We established thresholds for the Bayesian model to estimate the ischemic core. The described multiparametric Bayesian-based model improved consistency in CTP estimation of the ischemic core compared with the methodology used in current clinical routine.

Sequential Apparent Diffusion Coefficient for Assessment of Tumor Progression in Patients with Low-Grade Glioma

BACKGROUND AND PURPOSE

Early and accurate identification of tumor progression in patients with low-grade gliomas is challenging. We aimed to assess the role of quantitative ADC analysis in the sequential follow-up of patients with low-grade gliomas as a potential imaging marker of tumor stability or progression.

MATERIALS AND METHODS

In this retrospective study, patients with a diagnosis of low-grade glioma with at least 12 months of imaging follow-up were retrospectively reviewed. Two neuroradiologists independently reviewed sequential MR imaging in each patient to determine tumor progression using the Response Assessment in Neuro-Oncology criteria. Normalized mean ADC (ADC_mean) and 10th percentile ADC (ADC₁₀) values from FLAIR hyperintense tumor volume were calculated for each MR image and compared between patients with stable disease versus tumor progression using univariate analysis. The interval change of ADC values between sequential scans was used to differentiate stable disease from progression using the Fisher exact test.

RESULTS

Twenty-eight of 69 patients who were evaluated met our inclusion criteria. Fifteen patients were classified as stable versus 13 patients as having progression based on consensus reads of MRIs and the Response Assessment in Neuro-Oncology criteria. The interval change of ADC values showed greater concordance with ultimate lesion disposition than quantitative ADC values at a single time point. The interval change in ADC₁₀ matched the expected pattern in 12/13 patients with tumor progression (overall diagnostic accuracy of 86%, P <.001). On average, the ADC₁₀ interval change predicted progression 8 months before conventional MR imaging.

CONCLUSIONS

The interval change of ADC₁₀ values can be used to identify progression versus stability of low-grade gliomas with a diagnostic accuracy of 86% and before apparent radiologic progression on conventional MR imaging.

Abstract WMP22: Multiparametric CT Perfusion to Determine the Collaterals Status in Patients With Acute Ischemic Stroke: A New Perfusion Index

Introduction: Good collateral flow is an independent predictor of reperfusion that can be used to extend the treatment window in the new era of endovascular therapies for patients with acute ischemic stroke (AIS). Using a multiparametric approach, we aimed to identify perfusion parameter/s that can represent the extent of collaterals in comparison to CTA.

Methods: AIS patients with anterior circulation large vessel occlusion who had baseline CTA and CT perfusion were included. CT perfusion data were processed by Bayesian method to generate arterial tissue delay (ATD) maps at thresholds of 2 & 6 seconds. The volume of mild delayed perfusion (Vol-ATD >2sec ), moderate delayed (Vol-ATD 2-6sec ) and critical delayed perfusion (Vol-ATD >6sec ) in addition to corresponding rCBV and rCBF were calculated. Baseline CTA collaterals were scored using an established scoring scale1 and dichotomized to poor or good. The association of perfusion parameters and status of collaterals was assessed by repeated measure of analyses and receiver operating characteristic (ROC).

Results: In 28 patients included, 16 had good collaterals on CTA. After controlling for age, sex, baseline NIHSS and type of treatment, multivariate logistic regression analysis identified rCBV (p<0.001) and ATD 2-6sec (p=0.003), but not rCBF, Vol-ATD > 2sec or Vol-ATD >6sec , as independent predictors of good collaterals. ROC analysis showed AUC of 0.88 (sensitivity/specificity: 75%/100%) for rCBV and AUC of 0.84 (sensitivity/specificity: 93%/67%) for Vol-ATD 2-6sec . We defined a perfusion collateral index (PCI) calculated from Vol-ATD 2-6sec x its rCBV, that remained an independent predictor of good collaterals with improved diagnostic accuracy over each measure alone resulting in nominal AUC of 1 (sensitivity/specificity: 100%/100%).

Conclusions: Multiparametric CT perfusion can be used to assess the status of collaterals in patients with AIS. Perfusion collateral index (PCI) defined as Vol-ATD 2-6sec x rCBV is a new perfusion index with a nominal diagnostic accuracy of 100% compared to baseline CTA to predict status of collaterals in our small cohort. Our results need to be validated in a larger prospective cohort.

Whole-brain adaptive 70-kVp perfusion imaging with variable and extended sampling improves quality and consistency while reducing dose

BACKGROUND AND PURPOSE

Despite common use of CTP to assess cerebral hemodynamics in the setting of ischemia, concerns over radiation exposure remain. Our aim was to evaluate the efficacy of an adaptive 70-kVp (peak) whole-brain CTP protocol with variable sampling intervals and extended duration against an established fixed-sampling, limited-period protocol at 80 kVp.

MATERIALS AND METHODS

A retrospective analysis of 37 patients with stroke scanned with conventional (n = 17) and variant-protocol (n = 20) whole-brain CTP was performed. We compared radiation dose, parametric map quality, and consistency of full-contrast circulation capture between a modified 70-kVp protocol, with 20 whole-brain passes at variable sampling intervals over an extended sampling period, and a conventional 80-kVp CTP examination with 24 passes at fixed-sampling intervals and a more limited scanning window. Mann-Whitney U test analysis was used to compare both protocols.

RESULTS

The 70-kVp CTP scan provided superior image quality at a 45% lower CT dose index volume and 13% lower dose-length product/effective dose compared with the conventional 80-kVp scan. With respect to the consistency of contrast-passage capture, 95% of the adaptive, extended protocol continued through the venous return to baseline, compared with only 47% by using the conventional limited-length protocol. Rapid sampling during the critical arterial arrival and washout period was accomplished in nearly 95% with both the variable and fixed-sampling-interval protocols.

CONCLUSIONS

Seventy-kilovolt (peak) CTP with variable and extended sampling produces improved image quality at lower radiation doses with greater consistency of full contrast passage capture.

Radiation dose reduction in CT-guided spine biopsies does not reduce diagnostic yield

BACKGROUND AND PURPOSE

CT-guided biopsy is the most commonly used method to obtain tissue for diagnosis in suspected cases of malignancy involving the spine. The purpose of this study was to demonstrate that a low-dose CT-guided spine biopsy protocol is as effective in tissue sampling as a regular-dose protocol, without adversely affecting procedural time or complication rates.

MATERIALS AND METHODS

We retrospectively reviewed all patients who underwent CT-guided spine procedures at our institution between May 2010 and October 2013. Biopsy duration, total number of scans, total volume CT dose index, total dose-length product, and diagnostic tissue yield of low-dose and regular-dose groups were compared.

RESULTS

Sixty-four patients were included, of whom 31 underwent low-dose and 33 regular-dose spine biopsies. There was a statistically significant difference in total volume CT dose index and total dose-length product between the low-dose and regular-dose groups (P < .0001). There was no significant difference in the total number of scans obtained (P = .3385), duration of procedure (P = .149), or diagnostic tissue yield (P = .6017).

CONCLUSIONS

Use of a low-dose CT-guided spine biopsy protocol is a practical alternative to regular-dose approaches, maintaining overall quality and efficiency at reduced ionizing radiation dose.

An update to the Raymond-Roy Occlusion Classification of intracranial aneurysms treated with coil embolization

BACKGROUND

The Raymond-Roy Occlusion Classification (RROC) is the standard for evaluating coiled aneurysms (Class I: complete obliteration; Class II: residual neck; Class III: residual aneurysm), but not all Class III aneurysms behave the same over time.

METHODS

This is a retrospective review of 370 patients with 390 intracranial aneurysms treated with coil embolization. A Modified Raymond-Roy Classification (MRRC), in which Class IIIa designates contrast within the coil interstices and Class IIIb contrast along the aneurysm wall, was applied retrospectively.

RESULTS

Class IIIa aneurysms were more likely to improve to Class I or II than Class IIIb aneurysms (83.34% vs 14.89%, p<0.001) and were also more likely than Class II to improve to Class I (52.78% vs 16.90%, p<0.001). Class IIIb aneurysms were more likely to remain incompletely occluded than Class IIIa aneurysms (85.11% vs 16.67%, p<0.001). Class IIIb aneurysms were larger with wider necks while Class IIIa aneurysms had higher packing density. Class IIIb aneurysms had a higher retreatment rate (33.87% vs 6.54%, p<0.001) and a trend toward higher subsequent rupture rate (3.23% vs 0.00%, p=0.068).

CONCLUSIONS

We propose the MRRC to further differentiate Class III aneurysms into those likely to progress to complete occlusion and those likely to remain incompletely occluded or to worsen. The MRRC has the potential to expand the definition of adequate coil embolization, possibly decrease procedural risk, and help endovascular neurosurgeons predict which patients need closer angiographic follow-up. These findings need to be validated in a prospective study with independent blinded angiographic grading.

Repeated head CT in the neurosurgical intensive care unit: feasibility of sinogram-affirmed iterative reconstruction-based ultra-low-dose CT for surveillance

BACKGROUND AND PURPOSE

Patients in the neurosurgical intensive care unit undergo multiple head CT scans, resulting in high cumulative radiation exposures. Our aim was to assess the acceptability of a dedicated, special-purpose sinogram-affirmed iterative reconstruction-based ultra-low-dose CT protocol for neurosurgical intensive care unit surveillance head CT examinations, comparing image quality with studies performed with our standard-of-care sinogram-affirmed iterative reconstruction low-dose CT and legacy filtered back-projection standard-dose CT protocols.

MATERIAL AND METHODS

A retrospective analysis was performed of 54 head CT examinations: ultra-low-dose CT (n = 22), low-dose CT (n = 12), and standard-dose CT (n = 20) in 22 patients in the neurosurgical intensive care unit. Standard-dose CT was reconstructed by using filtered back-projection on a Somatom Sensation 64 scanner. Ultra-low-dose CT and ultra-low-dose CT examinations were performed on a Siemens AS+128 scanner with commercially available sinogram-affirmed iterative reconstruction. Qualitative and quantitative parameters, including image quality and dose, were evaluated.

RESULTS

Sinogram-affirmed iterative reconstruction ultra-low-dose CT represented a 68% lower dose index volume compared with filtered back-projection standard-dose CT techniques in the same patients while maintaining similar quality and SNR levels. Sinogram-affirmed iterative reconstruction low-dose CT offered higher image quality than filtered back-projection standard-dose CT (P < .05) with no differences in SNR at a 24% lower dose index volume. Compared with low-dose CT, ultra-low-dose CT had significantly lower SNR (P = .001) but demonstrated clinically satisfactory measures of image quality.

CONCLUSIONS

In this cohort of patients in the neurosurgical intensive care unit, dedicated ultra-low-dose CT for surveillance head CT imaging led to a significant dose reduction while maintaining adequate image quality.

Acute respiratory failure from Surgifoam expansion after anterior cervical surgery

A 65-year-old woman underwent an uneventful C3–4 anterior cervical discectomy and fusion for a large, symptomatic disc herniation. On postoperative Day 1 the patient suffered a sudden, acute respiratory compromise. Emergency fiberoptic intubation revealed significant anterior neck swelling with concern for physical obstruction of the airway. Computed tomography of the neck did not demonstrate an expanding hematoma. The patient was managed with surgical wound exploration and washout. Examination of the anterior neck after incision of the prior surgical site revealed a large volume of Surgifoam under high pressure, which was greater than the amount used during the initial surgery. Thorough washout of the surgical site did not reveal any swelling of the prevertebral soft tissues or hematoma, and the Hemovac drain did not appear to be occluded. The patient was extubated on the 2nd postoperative day and is symptom free 12 months after surgery. To the authors' knowledge, this report represents the first reported complication of acute respiratory failure from Surgifoam overexpansion after anterior cervical surgery.

Cervical tracheal compression in a patient with achalasia: an uncommon event

We report a case of a 79-year-old woman with long-standing achalasia that resulted in respiratory stridor and dyspnea. She was evaluated for tracheal compression with use of CT on inspiration and expiration. Airway obstruction and acute respiratory distress secondary to achalasia have been reported in the clinical literature. The importance of recognizing these rare manifestations is crucial for the appropriate treatment of these patients. In this patient, the CT evaluation of tracheal compression provided useful information on the degree of narrowing caused by the dilated esophagus.

Role of 3D CT in the Evaluation of the Temporal Bone

In recent years, three-dimensional (3D) multiplanar reformatted images from conventional cross-sectional computed tomographic (CT) data have been increasingly used to better demonstrate the anatomy and pathologic conditions of various organ systems. Three-dimensional volume-rendered (VR) CT images can aid in understanding the temporal bone, a region of complex anatomy containing multiple small structures within a relatively compact area, which makes evaluation of this region difficult. These images can be rotated in space and dissected in any plane, allowing assessment of the morphologic features of individual structures, including the small ossicles of the middle ear and the intricate components of the inner ear. The use of submillimeter two-dimensional reconstruction from CT data in addition to 3D reformation allows depiction of microanatomic structures such as the osseous spiral lamina and hamulus. Furthermore, 3D VR CT images can be used to evaluate various conditions of the temporal bone, including congenital malformations, vascular anomalies, inflammatory or neoplastic conditions, and trauma. The additional information provided by 3D reformatted images allows a better understanding of temporal bone anatomy and improves the ability to evaluate related disease, thereby helping to optimize surgical planning.