Radiation exposure of image-guided intrathecal administration of nusinersen to adult patients with spinal muscular atrophy.

PURPOSE: To examine diagnostic reference levels (DRL) and achievable doses (AD) of image-guided and size-specific dose estimates (SSDE) and organ and effective doses of CT-guided intrathecal nusinersen administration to adult patients with spinal muscular atrophy (SMA). METHODS: This study involved a total of 60 image-guided intrathecal nusinersen treatments between August 2017 and June 2018. Patient cohort comprised 14 adult patients with the following SMA types: type 2 (n = 9) and type 3 (n = 5) with a mean age of 33.6 years (age range 25-57 years). DRL, AD, SSDE, organ, and effective doses were assessed with a dose-monitoring program based on the Monte Carlo simulation techniques. RESULTS: DRL and AD for computed tomography are summarised as follows: in terms of CT-dose index (CTDIvol), DRL 56.4 mGy and AD 36.7 mGy; in terms of dose-length product (DLP), DRL 233.1 mGy cm and AD 120.1 mGy cm. DRL and AD for fluoroscopic guidance were distributed as follows: in terms of dose-area product (DAP), DRL 239.1 µGy m2 and AD 135.2 mGy cm2. Mean SSDE was 9.2 mGy. Mean effective dose of the CT-guided injections was 2.5 mSv (median 2.0 mSv, IQR 1.3-3.2 mSv). Highest organ doses in the primary beam of radiation were the small intestine 12.9 mSv, large intestine 9.5 mSv, and ovaries 3.6 mSv. CONCLUSION: Radiation exposure of SMA patients measured as DRLs is generally not higher compared with patients without SMA despite severe anatomical hazards. Dose monitoring data may allow clinicians to stratify radiation risk, identify organs at risk, and adopt measures for specific radiation dose reduction.

Detection of early infarction signs with machine learning-based diagnosis by means of the Alberta Stroke Program Early CT score (ASPECTS) in the clinical routine.

PURPOSE: New software solutions emerged to support radiologists in image interpretation in acute ischemic stroke. This study aimed to validate the performance of computer-aided assessment of the Alberta Stroke Program Early CT score (ASPECTS) for detecting signs of early infarction. METHODS: ASPECT scores were assessed in 119 CT scans of patients with acute middle cerebral artery ischemia. Patient collective was differentiated according to (I) normal brain, (II) leukoencephalopathic changes, (III) infarcts, and (IV) atypical parenchymal defects (multiple sclerosis, etc.). ASPECTS assessments were automatically provided by the software package e-ASPECTS (Brainomix®, UK) (A). Subsequently, three neuroradiologists (B), (C), and (D) examined independently 2380 brain regions. Interrater comparison was performed with the definite infarct core as reference standard after best medical care (thrombolysis and/or thrombectomy). RESULTS: Interrater comparison revealed higher correlation coefficient of (B) 0.71, (C) 0.76, and of (D) 0.80 with definite infarct core compared to (A) 0.59 for ASPECTS assessment in the acute ischemic stroke setting. While (B), (C), and (D) showed a significant correlation for individual patient groups (I), (II), (III), and (IV), except for (D) (II), (A) was not significant in patient groups with pre-existing changes (II), (III), and (IV). The following sensitivities, specificities, PPV, NPV, and accuracies given in percent were achieved: (A) 83, 57, 55, 82, and 67; (B) 74, 76, 69, 83, and 77; (C) 80.8, 85.2, 76, 84, and 80; (D) 63, 90.7, 82, 79, and 80, respectively. CONCLUSION: For ASPECTS assessment, the examined software may provide valid data in case of normal brain. It may enhance the work of neuroradiologists in clinical decision making. A final human check for plausibility is needed, particularly in patient groups with pre-existing cerebral changes.

Dose comparison of classical 2-plane DSA and 3D rotational angiography for the assessment of intracranial aneurysms.

INTRODUCTION: The purpose of this experimental phantom study was to compare radiation doses imparted to patients undergoing classical two-plane digital subtraction angiography (2-plane DSA) and 3D rotational angiography in interventional neuroradiology. METHODS: Thermoluminescence dosimeter (TLD) measurements were performed at an anthropomorphic phantom using a digital interventional angiography system. Two-plane DSA included posterior/anterior (PA) and lateral (LAT) projections (frame-rate, 7.6 frames (PA) and 9.8 frames (LAT) for a scan time of approximately 8 s; image intensifier 27 cm (PA) and 25 cm (LAT)). For 3D rotational angiography, 122 images were acquired from one single image run with the imaging system rotating 240° around the phantom's head (image intensifier 37 cm). RESULTS: Effective dose was 0.4 mSv for 2-plane DSA compared to 0.1 mSv for 3D rotational angiography. Organ doses were approximately two to five times higher for classical 2-plane technique compared to the 3D rotational angiography, respectively: brain (11.4 vs. 2.4 mSv), eye lens (4.5 vs.1 mSv), salivary glands (7 vs. 1,7 mSv), oral mucosa (2.7 vs.0.9 mSv), thyroid (0.5 vs. 0.2 mSv), thymus (0.2 vs. 0.05 mSv), bone marrow within imaged region (1 vs. 0.2 mSv), oesophagus (0.07 vs. 0.03 mSv), endotracheal system (2.6 vs. 0.7 mSv) and skeletal components in the imaged region (0.7 vs. 0.2 mSv). CONCLUSION: Three-dimensional rotational angiography clearly reduces radiation doses compared to the classical 2-plane technique. Replacement of additional 2-plane DSA projections with 3D rotational angiography will lead to a remarkable decrease in patient radiation dose, without loss of image quality. Thus, we recommend routine application of 3D rotational angiography, in particular for diagnostic assessment of aneurysm morphology.

Perspectives of Ultra-High-Field MRI in Neuroradiology.

PURPOSE: Magnetic resonance imaging (MRI) is one of the most important methods for the diagnosis and therapy monitoring of various diseases. Today, magnets up to 3 T are standard. This review will give an overview of the clinical perspectives of ultra-high field MRI, meaning mainly 7 T. METHODS: Literature review with focus on clinical applications of 7 T imaging in neuroscience combined with examples of own studies and perspectives. RESULTS: This high-resolution technique offers the potential to improve certain tissue contrasts and signal in functional (fMRI) and metabolic (MRS) imaging. This overview demonstrates already existing potentials and advantages of the ultra-high magnetic field for central nervous system (CNS) diseases. CONCLUSIONS: Although there are still some technical challenges for brain and spine imaging at 7 T, the method has clear benefit in selected structural, functional, and metabolic imaging.

3D Rotational Angiography After Non-Traumatic SAH.

PURPOSE: In about 15 % of patients with SAH no causative vascular lesions can be found in acute imaging with CTA and DSA. Usually, repeat DSA is mandatory and bears the usual risk of invasive angiography. The present study attempts to assess the diagnostic impact of 3 D rotational angiography in order to avoid repeat DSA. MATERIALS AND METHODS: From January 2004 to December 2012, 649 patients with an acute non-traumatic SAH were examined. 91 patients with negative initial imaging diagnostics concerning the bleeding source were included in this study. These patients underwent a second angiography scan: 61 in 4-plane technique, and 30 with 2-plane technique and additional 3 D DSA. Two cohorts were compared: patients with repeat angiography in conventional 4-plane technique from 2004 to July 2008 and 2-plane technique with additional 3 D rotational DSA from 2008 to 2012. Statistical significance was verified by means of Fisher's exact test. RESULTS: In the second DSA scan, 4 aneurysms in 4 patients (4/91; 4.4 %) were found and treated subsequently. Within the first 4.5 years of this study, 401 patients with SAH were treated and 61 of them underwent repeat angiography (15.2 %) compared to 30 of 248 patients (12.1 %) in the last 4.5 years of this study. In the first group we found 3 aneurysms during repeat angiography, and in the second group we found 1. No significance was reached (p = 0.29) but there was a tendency towards higher diagnostic security using 3D-DSA. CONCLUSION: Using 3 D rotational DSA in initial imaging workup might help to reduce false-negative results concerning the bleeding source of acute SAH. At least because of this fact, 3 D rotational DSA should be part of the diagnostic workup after acute SAH.

[3-year follow-up after endovascular aneurysm treatment with Silk® flow diverter]. / 3-Jahres-Follow nach Aneurysmabehandlung mit dem Silk® Flow Diverter.

PURPOSE: Flow diverters may occlude aneurysms by endoluminal reconstruction of the parent artery and by reducing the blood flow into the aneurysm. The purpose of this study was to assess the rate of intervention-associated complications and a 3-year-follow-up. MATERIALS AND METHODS: We retrospectively analyzed 18 patients treated with Silk® FD. Only patients with unruptured aneurysms were included. Treatment indications were fusiform, giant or recurrent aneurysms. We considered all aneurysms to have a high likelihood of failure and/or recurrence when treated with conventional endovascular techniques. RESULTS: Silk FD could directly be placed in a proper position across the whole length of the aneurysm in 16/18 patients. In one case an additional PTA was necessary. In another case the first FD could not be properly deployed. 17 of 18 aneurysms (95 %) were occluded immediately, in the mid-term follow-up after 6 months or 3 years after treatment. The overall complication rate including technical (11.1 %), acute or delayed thromboembolic complication without (11.1 %) or with (16.6 %) severe complications was documented. CONCLUSION: FD treatment is effective with a high occlusion rate of aneurysms also in long-term follow-up. In these complex aneurysms the complication rate is higher than in conventional stent-assisted coiling.

Imaging of brain metastases of bronchial carcinomas with 7 T MRI - initial results.

PURPOSE: To compare the depiction of brain metastases of bronchial carcinomas on susceptibility-weighted and contrast-enhanced images with 7 T and at 1.5 T MRI. MATERIALS AND METHODS: Twelve patients with brain metastases of bronchial carcinomas underwent 7 T and 1.5 T MRI. Minimum intensity projections (MinIP) of a 1.5 T SWI sequence (voxel size = 0.9 x 0.9 x 2.0 mm(3)) were compared to 7 T SWI MinIPs (voxel size = 0.4 x 0.4 x 1.5 mm(3)). A T 1-w 3D MPRAGE at 1.5 T (voxel size = 1 x 1 x 1 mm(3) after double-dose (DD) gadoterate meglumine, Gd-DOTA) was compared to a 7 T MPRAGE sequence (voxel size = 0.7 x 0.7 x x 0.7 mm(3), single dose (SD) Gd-DOTA) in all patients, and to DD Gd-DOTA in 6 patients after a 10 minute delay. The number of intracranial microhemorrhages in SWI MinIPs and the number of contrast-enhancing metastases in MPRAGE images were compared in each patient grouped into three size ranges (< or = 2 mm, > 2 mm and < 6 mm, > or = 6 mm) by two radiologists in consensus. RESULTS: In all 12 patients the 7 T SWI with spatially higher resolution allowed the identification of 87 versus 67 cerebral microhemorrhages at 1.5 T. 7 T T 1-w images after SD Gd-DOTA depicted 198 brain metastases versus 238 at 1.5 T after DD Gd-DOTA. After doubling the contrast dose in six patients, 4 additional brain metastases were identified at 7 T. CONCLUSION: Our preliminary results indicate that despite the higher spatial resolution the detection of brain metastases on 7 T MPRAGE images is almost equal to 1.5 T MPRAGE images. The 7 T SWI sequence with spatially higher resolution allowed the detection of 20 % more microhemorrhages in brain metastases compared to the 1.5 T SWI sequence.

Evaluation of intracranial aneurysms with 7 T versus 1.5 T time-of-flight MR angiography - initial experience.

PURPOSE: The purpose of this study was to compare the depiction of intracranial aneurysms by 3D time-of-flight (TOF) magnetic resonance angiography (MRA) at 7 Tesla (T) with the clinical standard TOF MRA at 1.5 T and with digital subtraction angiography (DSA). MATERIALS AND METHODS: 7 T and 1.5 T TOF MRA images optimized for both field strengths were compared in ten patients with an unruptured intracranial aneurysm. Two blinded neuroradiologists independently rated the image quality of the dome, the neck, and the vessel of origin of all aneurysms in MRA source and maximum intensity projection (MIP) images. DSA was obtained in all subjects and served as reference standard. The mean values of image quality were compared by Wilcoxon signed rank test. In all patients the number and location of the aneurysms was confirmed by DSA. RESULTS: Both readers identified twelve aneurysms in ten patients in 7 T, 1.5 T TOF MRA and DSA. The image quality of the aneurysm dome was rated higher in 8 of 12 aneurysms and the image quality of the aneurysm neck was superior in 9 of 12 aneurysms at 7 T TOF MRA compared to 1.5 T TOF MRA. The depiction of the parent vessel was graded almost equally by both readers. CONCLUSION: Our initial results indicate that image quality of intracranial aneurysms may benefit from the increased spatial resolution of 7 T TOF MRA compared with 1.5 T TOF MRA. Tailored scan protocols and optimized radiofrequency head coils are needed to further improve the image quality of 7 T TOF MRA.