Monitoring Radiation Doses during Diagnostic and Therapeutic Neurointerventional Procedures: Multicenter Study for Establishment of Reference Levels / 신경중재치료의학

Purpose@#To assess patient radiation doses during diagnostic and therapeutic neurointerventional procedures from multiple centers and propose dose reference level (RL). @*Materials and Methods@#Consecutive neurointerventional procedures, performed in 22 hospitals from December 2020 to June 2021, were retrospectively studied. We collected data from a sample of 429 diagnostic and 731 therapeutic procedures. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time (FT), and total number of image frames (NI) were obtained. RL were calculated as the 3rd quartiles of the distribution. @*Results@#Analysis of 1160 procedures from 22 hospitals confirmed the large variability in patient dose for similar procedures. RLs in terms of DAP, CAK, FT, and NI were 101.6 Gy·cm2, 711.3 mGy, 13.3 minutes, and 637 frames for cerebral angiography, 199.9 Gy·cm2, 3,458.7 mGy, 57.3 minutes, and 1,000 frames for aneurysm coiling, 225.1 Gy·cm2, 1,590 mGy, 44.7 minutes, and 800 frames for stroke thrombolysis, 412.3 Gy·cm2, 4,447.8 mGy, 99.3 minutes, and 1,621.3 frames for arteriovenous malformation (AVM) embolization, respectively. For all procedures, the results were comparable to most of those already published. Statistical analysis showed male and presence of procedural complications were significant factors in aneurysmal coiling. Male, number of passages, and procedural combined technique were significant factors in stroke thrombolysis. In AVM embolization, a significantly higher radiation dose was found in the definitive endovascular cure group. @*Conclusion@#Various RLs introduced in this study promote the optimization of patient doses in diagnostic and therapeutic interventional neuroradiology procedures. Proposed 3rd quartile DAP (Gy·cm2) values were 101.6 for diagnostic cerebral angiography, 199.9 for aneurysm coiling, 225.1 for stroke thrombolysis, and 412.3 for AVM embolization. Continual evolution of practices and technologies requires regular updates of RLs.

Susceptibility-Weighted MR Imaging for the Detection of Isolated Cortical Vein Thrombosis in a Patient with Spontaneous Intracranial Hypotension

Spontaneous intracranial hypotension (SIH) can be a rare risk factor of cerebral venous thrombosis. We describe a case of isolated cortical vein thrombosis (CVT) secondary to SIH and discuss the value of susceptibility-weighted imaging for the detection of isolated CVT.

Arterial Spin Labelling Perfusion, Proton MR Spectroscopy and Susceptibility-Weighted MR Findings of Acute Necrotizing Encephalopathy: a Case Report

In this study, we report arterial spin labelling perfusion, proton MR spectroscopy and susceptibility-weighted MR findings of acute necrotizing encephalopathy in a child with rotavirus infection.

MR Findings of Seizure-Related Cerebral Cortical Lesions during Periictal Period

PURPOSE: This study investigated the MRI, MR angiography (MRA) and MR perfusion findings of seizure-related cerebral cortical lesions during the periictal period. MATERIALS AND METHODS: From a retrospective review of the institutional database between 2011 and 2014, a total of 21 patients were included in this study. Two radiologists assessed periictal MRI, including MRA and MR perfusion, in patients with seizure-related cortical lesions. The parameters examined include: location of cortical abnormality, multiplicity of the affected cortical region, cerebral vascular dilatation, perfusion abnormality and other parenchymal lesions. RESULTS: All patients showed T2 hyperintense cerebral cortical lesions with accompanying diffusion restriction, either unilateral (18/21, 85.7%) or bilateral (3/21, 14.3%). Of the 21 patients enrolled, 10 (47.6%) had concurrent T2 hyperintense thalamic lesions, and 10 (47.6%) showed hippocampal involvement. Of the 17 patients (81%) who underwent MRA, 13 (76.5%) showed vascular dilatation with increased flow signal in the cerebral arteries of the affected cortical regions. On MR perfusion, all 5 patients showed cortical hyperperfusion, corresponding to the region of cortical abnormalities. CONCLUSION: Seizure-related cerebral cortical lesions are characterized by T2 and diffusion hyperintensities, with corresponding cerebral hyperperfusion and vascular dilatation. These findings can be helpful for making an accurate diagnosis in patients with seizure.

MR Findings of Seizure-Related Cerebral Cortical Lesions during Periictal Period

PURPOSE: This study investigated the MRI, MR angiography (MRA) and MR perfusion findings of seizure-related cerebral cortical lesions during the periictal period. MATERIALS AND METHODS: From a retrospective review of the institutional database between 2011 and 2014, a total of 21 patients were included in this study. Two radiologists assessed periictal MRI, including MRA and MR perfusion, in patients with seizure-related cortical lesions. The parameters examined include: location of cortical abnormality, multiplicity of the affected cortical region, cerebral vascular dilatation, perfusion abnormality and other parenchymal lesions. RESULTS: All patients showed T2 hyperintense cerebral cortical lesions with accompanying diffusion restriction, either unilateral (18/21, 85.7%) or bilateral (3/21, 14.3%). Of the 21 patients enrolled, 10 (47.6%) had concurrent T2 hyperintense thalamic lesions, and 10 (47.6%) showed hippocampal involvement. Of the 17 patients (81%) who underwent MRA, 13 (76.5%) showed vascular dilatation with increased flow signal in the cerebral arteries of the affected cortical regions. On MR perfusion, all 5 patients showed cortical hyperperfusion, corresponding to the region of cortical abnormalities. CONCLUSION: Seizure-related cerebral cortical lesions are characterized by T2 and diffusion hyperintensities, with corresponding cerebral hyperperfusion and vascular dilatation. These findings can be helpful for making an accurate diagnosis in patients with seizure.

Functional Magnetic Resonance Imaging with Arterial Spin Labeling: Techniques and Potential Clinical and Research Applications

PURPOSE: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. MATERIALS AND METHODS: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. RESULTS: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. CONCLUSION: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.

Functional Magnetic Resonance Imaging with Arterial Spin Labeling: Techniques and Potential Clinical and Research Applications

PURPOSE: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. MATERIALS AND METHODS: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. RESULTS: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. CONCLUSION: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.

Arterial Spin Labeling Perfusion MRI of Crossed Cerebellar Diaschisis in a Patient with Simple Partial Status Epilepticus

Crossed cerebellar diaschisis (CCD) is known to be due to a contralateral supratentorial lesion decreasing blood flow and the metabolism in a cerebellar hemisphere. Arterial spin labeling (ASL) is an imaging technique that utilizes arterial blood water as a tracer for quantifying the regional cerebral blood flow in magnetic resonance imaging (MRI). This case was a patient with simple partial status epilepticus (SPSE) and CCD confirmed by ASL-perfusion MRI. Controlling the SPSE resulted in improvement of CCD being observed in the follow-up ASL-perfusion MRI.

Splenial Lesions of the Corpus Callosum: Disease Spectrum and MRI Findings

The corpus callosum (CC) is the largest white matter structure in the brain, consisting of more than 200–250 million axons that provide a large connection mainly between homologous cerebral cortical areas in mirror image sites. The posterior end of the CC is the thickest part, which is called the splenium. Various diseases including congenital to acquired lesions including congenital anomalies, traumatic lesions, ischemic diseases, tumors, metabolic, toxic, degenerative, and demyelinating diseases, can involve the splenium of the CC and their clinical symptoms and signs are also variable. Therefore, knowledge of the disease entities and the imaging findings of lesions involving the splenium is valuable in clinical practice. MR imaging is useful for the detection and differential diagnosis of splenial lesions of the CC. In this study, we classify the disease entities and describe imaging findings of lesions involving the splenium of the CC based on our experiences and a review of the literature.

Clinical Experiences of Uncommon Motor Neuron Disease: Hirayama Disease

Hirayama disease, juvenile muscular atrophy of the distal upper limb, is a rare disease predominantly affecting the anterior horn cells of the cervical spinal cord in young men. This cervical myelopathy is associated with neck flexion. It should be suspected in young male patients with a chronic history of weakness and atrophy involving the upper extremities followed by clinical stability in few years. Herein, we report 2 cases of Hirayama disease on emphasis of diagnostic approach and describe the pathognomonic findings at flexion magnetic resonance imaging.

Susceptibility Vessel Sign for the Detection of Hyperacute MCA Occlusion: Evaluation with Susceptibility-weighted MR Imaging

PURPOSE: Susceptibility vessel sign (SVS) on gradient echo image, which is caused by MR signal loss due to arterial thrombosis, has been reported in acute middle cerebral artery (MCA) infarction. However, the reported sensitivity and diagnostic accuracy of SVS have been variable. Susceptibility-weighted imaging (SWI) is a newly developed MR sequence. Recent studies have found that SWI may be useful in the field of cerebrovascular diseases, especially for detecting the presence of prominent veins, microbleeds and the SVS. The purpose of this study was to evaluate the diagnostic values of SWI for the detection of hyperacute MCA occlusion. MATERIALS AND METHODS: Sixty-nine patients (37 males, 32 females; 46-89 years old [mean, 69.1]) with acute stroke involving the MCA territory underwent MR imaging within 6 hours after the symptom onset. MR examination included T2, FLAIR (fluid-attenuated inversion recovery), DWI, SWI, PWI (perfusion-weighted imaging), contrast-enhanced MR angiography (MRA) and contrast-enhanced T1. Of these patients, 28 patients also underwent digital subtraction angiography (DSA) within 2 hours after MR examination. Presence or absence of SVS on SWI was assessed without knowledge of clinical, DSA and other MR imaging findings. RESULTS: On MRA or DSA, 34 patients (49.3%) showed MCA occlusion. Of these patients, SVS was detected in 30 (88.2%) on SWI. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of SWI were 88.2%, 97.1%, 96.8%, 89.5% and 92.8%, respectively. CONCLUSION: SWI was sensitive, specific and accurate for the detection of hyperacute MCA occlusion.

Nontraumatic Intracystic Hemorrhage of Arachnoid Cyst: CT and MR Findings

Arachnoid cysts (AC) are intraarachnoidal cerebrospinal fluid collections, and account for 1% of all intracranial space-occupying lesions. Intracystic hemorrhage of the AC can occur spontaneously, but this is an extremely rare event. Herein, we present a case of hemorrhagic AC in a nontraumatic patient in the left middle cranial fossa. We also performed relevant literature review on this disease.

Patient Radiation Exposure During Diagnostic and Therapeutic Procedures for Intracranial Aneurysms: A Multicenter Study / 신경중재치료의학

PURPOSE: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL). MATERIALS AND METHODS: We studied a sample of 490 diagnostic and 371 therapeutic procedures for intracranial aneurysms, which were performed at 23 hospitals in Korea in 2015. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time and total angiographic image frames were obtained and analyzed. RESULTS: Total mean DAP, CAK, fluoroscopy time, and total angiographic image frames were 106.2 ± 66.4 Gy-cm2, 697.1 ± 473.7 mGy, 9.7 ± 6.5 minutes, 241.5 ± 116.6 frames for diagnostic procedures, 218.8 ± 164.3 Gy-cm², 3365.7 ± 2205.8 mGy, 51.5 ± 31.1 minutes, 443.5 ± 270.7 frames for therapeutic procedures, respectively. For diagnostic procedure, the third quartiles for DRLs were 144.2 Gy-cm² for DAP, 921.1 mGy for CAK, 12.2 minutes for fluoroscopy times and 286.5 for number of image frames, respectively. For therapeutic procedures, the third quartiles for DRLs were 271.0 Gy-cm² for DAP, 4471.3 mGy for CAK, 64.7 minutes for fluoroscopy times and 567.3 for number of image frames, respectively. On average, rotational angiography was used 1.5 ± 0.7 times/session (range, 0-4; n=490) for diagnostic procedures and 1.6 ± 1.2 times/session (range, 0-4; n=368) for therapeutic procedures, respectively. CONCLUSION: Radiation dose as measured by DAP, fluoroscopy time and image frames were lower in our patients compared to another study regarding cerebral angiography, and DAP was lower with fewer angiographic image frames for therapeutic procedures. Proposed DRLs can be used for quality assurance and patient safety in diagnostic and therapeutic procedures.

Associated Brain Parenchymal Abnormalities in Developmental Venous Anomalies: Evaluation with Susceptibility-weighted MR Imaging

PURPOSE: The purpose of this study was to evaluate the associated brain parenchymal abnormalities of developmental venous anomalies (DVA) with susceptibility-weighted image (SWI). MATERIALS AND METHODS: Between January 2012 and June 2013, 2356 patients underwent brain MR examinations with contrast enhancement. We retrospectively reviewed their MR examinations and data were collected as per the following criteria: incidence, locations, and associated parenchymal signal abnormalities of DVAs on T2-weighted image, fluid-attenuated inversion recovery (FLAIR), and SWI. Contrast enhanced T1-weighted image was used to diagnose DVA. RESULTS: Of the 2356 patients examined, 57 DVAs were detected in 57 patients (2.4%); 47 (82.4%) were in either lobe of the supratentorial brain, 9 (15.7%) were in the cerebellum, and 1 (1.7%) was in the pons. Of the 57 DVAs identified, 20 (35.1%) had associated parenchymal abnormalities in the drainage area. Among the 20 DVAs which had associated parenchymal abnormalities, 13 showed hemorrhagic foci on SWI, and 7 demonstrated only increased parenchymal signal abnormalities on T2-weighted and FLAIR images. In 5 of the 13 patients (38.5%) who had hemorrhagic foci, the hemorrhagic lesions were demonstrated only on SWI. CONCLUSION: The overall incidence of DVAs was 2.4%. Parenchymal abnormalities were associated with DVAs in 35.1% of the cases. On SWI, hemorrhage was detected in 22.8% of DVAs. Thus, we conclude that SWI might give a potential for understanding of the pathophysiology of parenchymal abnormalities in DVAs.

Evaluation of Hippocampal Volume Based on Various Inversion Time in Normal Adults by Manual Tracing and Automated Segmentation Methods

PURPOSE: To investigate the value of image post-processing software (FreeSurfer, IBASPM [individual brain atlases using statistical parametric mapping software]) and inversion time (TI) in volumetric analyses of the hippocampus and to identify differences in comparison with manual tracing. MATERIALS AND METHODS: Brain images from 12 normal adults were acquired using magnetization prepared rapid acquisition gradient echo (MPRAGE) with a slice thickness of 1.3 mm and TI of 800, 900, 1000, and 1100 ms. Hippocampal volumes were measured using FreeSurfer, IBASPM and manual tracing. Statistical differences were examined using correlation analyses accounting for spatial interpretations percent volume overlap and percent volume difference. RESULTS: FreeSurfer revealed a maximum percent volume overlap and maximum percent volume difference at TI = 800 ms (77.1 +/- 2.9%) and TI = 1100 ms (13.1 +/- 2.1%), respectively. The respective values for IBASPM were TI = 1100 ms (55.3 +/- 9.1%) and TI = 800 ms (43.1 +/- 10.7%). FreeSurfer presented a higher correlation than IBASPM but it was not statistically significant. CONCLUSIONS: FreeSurfer performed better in volumetric determination than IBASPM. Given the subjective nature of manual tracing, automated image acquisition and analysis image is accurate and preferable.

T1-weighted FLAIR MR Imaging for the Evaluation of Enhancing Brain Tumors: Comparison with Spin Echo Imaging

PURPOSE: Spin-echo (SE) technique is most commonly used pulse sequence for T1-weighted MR imaging. T1-weighted fluid-attenuated inversion recovery (T1FLAIR) is a relatively new pulse sequence and it provides higher tissue contrast between the gray matter (GM) and white matter (WM) of the brain than T1-weighted SE (T1SE) sequence. However, there has been controversy for the evaluation of enhancing brain tumors with T1FLAIR compared to T1SE. The purpose of this study was to compare T1FLAIR and T1SE sequences for the evaluation of enhancing intracranial tumors. MATERIALS AND METHODS: Fifty-two patients with enhancing brain tumors were evaluated with contrast-enhanced (CE) T1SE and T1FLAIR imaging. Eight quantitative criteria were calculated: lesion-to-WM contrast ratio (CR) and contrast-to-noise ratio (CNR), lesion-to-GM CR and CNR, lesion-to-CSF CR and CNR, and WM-to-GM CR and CNR. For qualitative evaluation, two radiologists assessed lesion conspicuity on CE T1SE and T1FLAIR sequences with three-scale: 1, T1SE superior; 2, sequence equal; T1FLAIR superior. RESULTS: Seventy-nine tumors (31 primaries, 48 metastases) were assessed. For quantitative measurement, the T1FLAIR lesion-to-GM, lesion-to-CSF, WM-to-GM CR and CNR values were comparable and statistically superior to those of the T1SE images (p < 0.001 in all). However, lesion-to-WM CR and CNR were similar on both two sequences without statistically significant difference (p = 0.661, 0.662, respectively). For qualitative evaluation, both radiologists assessed that T1FLAIR images were superior to T1SE images for the evaluation of lesion conspicuity. CONCLUSION: For the evaluation of enhancing intracranial tumors, T1FLAIR sequence was superior or comparable to T1SE sequence.

Susceptibility-Weighted MR Imaging for the Detection of Developmental Venous Anomaly: Comparison with T2 and FLAIR Imaging

PURPOSE: We evaluated the diagnostic value of susceptibility-weighted imaging (SWI) for the detection of developmental venous anomaly (DVA). MATERIALS AND METHODS: Retrospective review of 1068 brain MR examinations found 28 DVAs in 28 patients (2.6%) on contrast-enhanced T1-weighted images. SWI, T2, and FLAIR images of 28 patients with DVA and 28 sex- and age-matched control patients without DVA were analyzed by blinded readers on each type of sequences. All images were independently reviewed by two radiologists who were blinded to other MR imaging finding. In cases of discrepancy, two reviewers reached a consensus later. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each MR sequence for the detection of DVA were determined. Statistical analysis was performed by using the Mcnemar test. The significance level was p < 0.05. RESULTS: The sensitivity, specificity, PPV, and NPV of SWI for the detection of DVA were 85.7%, 92.9%, 92.3%, and 86.7%, respectively. T2 and FLAIR images showed sensitivity of 35.7% and 35.7%, specificity of 92.9% and 96.4%, PPV of 83.3% and 90.9%, and NPV of 59.1% and 60.0%, respectively. On SWI, the sensitivity and NPV for the detection of DVAs were significantly higher than those of T2 and FLAIR images (p < 0.05). CONCLUSION: SWI was sensitive and specific for the detection of DVA.

Ictal Images of Simple Partial Status Epilepticus

No abstract available.

Assessment of Cerebral Vascular Reserve Capacity Prior to Carotid ArteryStenting: Brain Single Photon Emission Computed Tomography images and Magnetic Resonance Arterial Spin Labeling images

No abstract available.

A Study of Changes of Inversion Time Effect on Brain Volume of Normal Volunteers

PURPOSE: The objective of this study was to analyze the brain volume according to the brain image of healthy adults in the 20s taken with different inversion time (TI). MATERIALS AND METHODS: Brain images of healthy adults in the 20 s were acquired using magnetization prepared rapid acquisition gradient echo (MPRAGE) pulse sequence with 1.5 mm thickness of pieces and four inversion times (1100 ms, 1000 ms, 900 ms, 800 ms). The acquired brain images were analyzed to measure the volume of white matter (WM), gray matter (GM), intracranial volume (ICV). The statistical difference according to brain volume and gender was analyzed for each TI. RESULTS: The brain volume calculated using Freesurfer was WM=486.52+/-48.64 cm3 and GM=646.86+/-57.12 cm3 in mean when adjusted by mean ICV=1278.94+/-154.92 cm3. Men's brain volume(WM, GM, ICV) was larger than women's brain volume. In the intrarater reliability test, all of the intraclass correlation coefficients were high (0.992 for WM, 0.988 for GM, and 0.997 for ICV). In the repeated measures analysis of variance, GM and ICV did not show a significant difference at each TI (GM p=0.143, ICV p=0.052), but WM showed a significant (p=0.001). In the linear structure relation analysis, all of the Pearson correlation coefficients were high. CONCLUSION: WM, GM, and ICV indicated high reliability and solid linear structure relations, but WM showed significant differences at each TI. The brain volume of healthy adults in the 20s could be used in comparison with that of patients for reference purposes and to predict the structural change of brain. It would be needed to conduct additional studies to examine the contract, SNR, and lesion detection ability according to variable TI.