We studied in a clinical setting the age dependent T1 relaxation time as a marker of normal late brain maturation and compared it to conventional techniques, namely the apparent diffusion coefficient ...(ADC).
Forty-two healthy subjects ranging from ages 1 year to 20 years were included in our study. T1 brain maps in which the intensity of each pixel corresponded to T1 relaxation times were generated based on MR imaging data acquired using a MP2RAGE sequence. During the same session, diffusion tensor imaging data was collected. T1 relaxation times and ADC in white matter and grey matter were measured in seven clinically relevant regions of interest and were correlated to subjects' age.
In the basal ganglia, there was a small, yet significant, decrease in T1 relaxation time (-0.45 ≤R≤-0.59, p<10-2) and ADC (-0.60≤R≤-0.65, p<10-4) as a function of age. In the frontal and parietal white matter, there was a significant decrease in T1 relaxation time (-0.62≤R≤-0.68, p<10-4) and ADC (-0.81≤R≤-0.85, p<10-4) as a function of age. T1 relaxation time changes in the corpus callosum and internal capsule were less relevant for this age range. There was no significant difference between the correlation of T1 relaxation time and ADC with respect to age (p-value = 0.39). The correlation between T1 relaxation and ADC is strong in the white matter but only moderate in basal ganglia over this age period.
T1 relaxation time is a marker of brain maturation or myelination during late brain development. Between the age of 1 and 20 years, T1 relaxation time decreases as a function of age in the white matter and basal ganglia. The greatest changes occur in frontal and parietal white matter. These regions are known to mature in the final stage of development and are mainly composed of association circuits. Age-correlation is not significantly different between T1 relaxation time and ADC. Therefore, T1 relaxation time does not appear to be a superior marker of brain maturation than ADC but may be considered as complementary owing the intrinsic differences in bio-physical sensitivity. This work may serve as normative ranges in clinical imaging routines.
Introduction: Head and neck extracranial arteriovenous malformations (AVMs) are rare pathological conditions which pose diagnostic and reconstruction challenges. Stereotactic radiosurgery (SRS) is ...nowadays an established treatment method for brain AVMs, with high obliteration and low complication rates. Here we describe the first report of head extracranial AVMs successfully treated by Gamma Knife (GK) as a retrospective historical cohort. Methods: Over a 9-year period, 2 cases of extracranial AVMs were treated by GK Perfexion (Elekta Instruments AB, Stockholm, Sweden) at a single institution. A stereotactic frame and multimodal imaging, including digital subtraction angiography (DSA), were used. The prescribed dose was 24 Gy at the 50% isodose line. Results: The first case was of a patient with pulsating tinnitus and left superficial parotido-condylian AVM. Embolization achieved partial obliteration. Tinnitus disappeared during the following 6 months after GK. The second case was a patient with repetitive gingival hemorrhages and right superior maxillary AVM, fed by the right internal maxillary and facial arteries. Embolization achieved partial obliteration with recurrence of symptoms. GK was further performed. DSA confirmed complete obliteration in both patients. Conclusions: Single-fraction GK radiosurgery appears to be safe and effective for extracranial AVMs. We recommend prescribing doses that are comparable to the ones used for brain AVMs (i.e., 24 Gy). A stereotactic frame is an important tool to ensure higher accuracy in the context of these particular locations. However, in selected cases, a mask could be applied either for single fraction purposes (if in a non-mobile location) or for hypofractionation, in case of larger volumes. These findings should be validated in larger cohorts, inclusively in terms of dose prescription.
We investigated the ability of early alteration of cerebral perfusion-computed tomography (PCT) parameters to predict the risk of vasospasm, delayed cerebral ischemia (DCI), and clinical outcome in ...patients with aneurysmal subarachnoid hemorrhage (aSAH).
A retrospective cohort study of 38 aSAH patients investigated with PCT within 48 hours after hemorrhage. Cerebral blood flow (CBF), cerebral blood volume, and mean transit time (MTT) values were recorded. Mean values were compared with clinical data. Vasospasm and DCI were determined by imaging and clinical criteria. Neurologic outcome was assessed by the modified Rankin Scale at discharge and 1-year follow-up visit.
More than a third (39.5%) of patients developed DCI, of whom 86.7% presented moderate-severe vasospasm. There was a significant correlation between perfusion parameters in the early phase and occurrence of DCI and vasospasm. The occurrence of DCI and vasospasm correlated significantly with lower mean early PCT values. DCI was correlated with lower mean early CBF values (P = 0.049) and vasospasm with lower mean CBF (P = 0.01) and MTT (P < 0.00001) values. MTT values of 5.5s were shown to have 94% specificity and 100% sensitivity for predicting the risk of developing vasospasm. The severity of the SAH according to the Barrow Neurological Institute scale correlated significantly with the risk of developing DCI and vasospasm, both significantly associated with unfavorable neurologic outcome (modified Rankin Scale score 3-6) (P = 0.0002 and P = 0.02, respectively).
Early alterations in PCT parameters and high Barrow Neurological Institute grade may identify a subgroup of patients at high risk of developing DCI and vasospasm after aSAH, thus prompting more robust preventative measures and treatment in this subgroup.
Background:
Intraoperative identification of the correct level during thoracic spine surgery is essential to avoid wrong-level procedures. Despite technological progress, intraoperative imaging ...modalities for identifying the correct thoracic spine level remain unreliable and often lead to wrong-level surgery. To counter potential wrong-level operations, here, we have proposed a novel pedicle/bone cylinder marking technique for use in the thoracic spine utilizing biplanar fluoroscopy and confirmed with computed tomography (CT).
Methods:
First, under fluoroscopic guidance, a bone cylinder is removed from the correct thoracic pedicle. Next, endovascular coils are packed into the cancellous bone defect followed by reinsertion of the bony plug. The patient then undergoes a CT scan of the entire thoracolumbosacral spine to precisely identify the marked level before surgery.
Results:
We utilized this bone cylinder plug/coil technique to identify the T9-T10 level in a 56-year-old female with a soft thoracic disc herniation. The index thoracic pedicle was successfully localized before performing the unilateral minimally invasive laminectomy followed by the transpedicular thoracic disc excision.
Conclusion:
The bone cylinder plug/coil technique is a safe and effective method for marking the correct level in thoracic spine surgery, while also reducing the operative time.
The relative value of computed tomography (CT) and magnetic resonance imaging (MRI) in acute ischemic stroke (AIS) is debated. In May 2018, our center transitioned from using CT to MRI as first-line ...imaging for AIS. This retrospective study aims to assess the effects of this paradigm change on diagnosis and disability outcomes.
We compared all consecutive patients with confirmed diagnosis of AIS admitted to our center during the MRI-period (May 2018-August 2022) and an identical number of patients from the preceding CT-period (December 2012-April 2018). Univariable and multivariable analyses were performed to evaluate outcomes, including the number and delay of imaging exams, the rate of missed strokes, stroke mimics treated with thrombolysis, undetermined stroke mechanisms, length of hospitalization, and 3-month disability.
The median age of the 2972 included patients was 76 years (interquartile range, 65-84), and 46% were female. In the MRI-period, 80% underwent MRI as first acute imaging. The proportion of patients requiring a second acute imaging modality for diagnostic ± revascularization reasons increased from 2.1% to 5% (
<0.05), but it decreased in the subacute phase from 79.0% to 60.1% (
<0.05). In thrombolysis candidates, there was a 2-minute increase in door-to-imaging delay (
<0.05). The rates of initially missed AIS diagnosis was similar (3.8% versus 4.4%,
=0.32) and thrombolysis in stroke mimics decreased by half (8.6% versus 4.3%;
<0.05). Rates of unidentified stroke mechanism at hospital discharge were similar (22.8% versus 28.1%;
=0.99). The length of hospitalization decreased from 9 (interquartile range, 6-14) to 7 (interquartile range, 4-12) days (
=0.62). Disability at 3 months was similar (common adjusted odds ratio for favorable Rankin shift, 0.98 95% CI, 0.71-1.36;
=0.91), as well as mortality and symptomatic intracranial hemorrhage.
A paradigm shift from CT to MRI as first-line imaging for AIS seems feasible in a comprehensive stroke center, with a minimally increased delay to imaging in thrombolysis candidates. MRI was associated with reduced thrombolysis rates of stroke mimics and subacute neuroimaging needs.
Little is known on the role of mismatch profile in patients undergoing early endovascular treatment (EVT). We aimed to describe pretreatment perfusion parameters and mismatch profiles in anterior ...circulation large vessel occlusion acute ischemic stroke undergoing EVT in the early time window and assess their association with time from stroke onset and outcomes.
Retrospective single-center study, including early (<6 hours) EVT-treated large vessel occlusion acute ischemic stroke with baseline perfusion data, assessing perfusion parameters (ischemic core volume, mismatch volume and mismatch ratio) and mismatch profiles (favorable versus unfavorable, based on criteria adopted in EXTEND-IA Extending the Time for Thrombolysis in Emergency Neurological Deficits - Intra-Arterial, SWIFT PRIME Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment, DEFUSE 3 Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke 3, and DAWN Clinical Mismatch in the Triage of Wake Up and Late Presenting Strokes Undergoing Neurointervention With Trevo trials). We evaluated their association with time from stroke onset (r
for parameters or χ
for trend for profiles) and association with modified Rankin Scale score >2, symptomatic intracranial hemorrhage, and mortality (multivariate regression analyses each parameter/profile entered into a separate logistic regression model, adjusted for baseline variables associated with each outcome in the univariate analysis at the
<0.1 level).
Among 357 patients, unfavorable mismatch profiles ranged from 21% to 60%, depending on the criterion, and were not correlated with time from stroke onset (
=0.490). All individual perfusion parameters and unfavorable mismatch profiles were associated with poor functional outcome: ischemic core volume adjusted odds ratio (aOR), 1.49 (95% CI, 1.13-1.97
=0.005); penumbral volume aOR, 0.30 (95% CI, 0.10-0.84
=0.022); mismatch ratio aOR, 0.67 (95% CI, 0.50-0.90
=0.007); EXTEND-IA aOR, 2.61 (95% CI, 1.23-5.51
=0.012); SWIFT PRIME aOR, 2.50 (95% CI, 1.30-4.57
=0.006); DEFUSE 3 aOR, 2.28 (95% CI, 1.14-4.57
=0.020); and DAWN aOR, 4.19 (95% CI, 2.13-8.26
<0.001). EXTEND-IA and DEFUSE 3 unfavorable profiles were also independently associated with symptomatic intracranial hemorrhage (aOR, 3.82 95% CI, 1.42-10.3;
=0.008 and aOR, 2.83 95% CI, 1.09-7.36;
=0.033) and death (aOR, 3.26 95% CI, 1.33-8.02;
=0.010 and aOR, 2.52 95% CI, 1.10-5.82;
=0.030).
Pretreatment perfusion parameters and mismatch profiles in early EVT-treated patients were not correlated with time from stroke onset but were independently associated with functional outcome. Mismatch assessment in the early time window may improve EVT patient selection, independently of onset-to-treatment time.
Objectives
To determine and compare the qualitative and quantitative diagnostic performance of a single sagittal fast spin echo (FSE) T2-weighted Dixon sequence in differentiating benign and ...malignant vertebral compression fractures (VCF), using multiple readers and different quantitative methods.
Methods
From July 2014 to June 2020, 95 consecutive patients with spine MRI performed prior to cementoplasty for acute VCFs were retrospectively included. VCFs were categorized as benign (
n
= 63, mean age = 76 ± 12 years) or malignant (
n
= 32, mean age = 63 ± 12 years) with a best valuable comparator as a reference. Qualitative analysis was independently performed by four radiologists by categorizing each VCF as either benign or malignant using only the image sets provided by FSE T2-weighted Dixon sequences. Quantitative analysis was performed using two different regions of interest (ROI1-2) and three methods (signal drop, fat fraction (FF) from ROIs, FF maps). Diagnostic performance was compared using ROC curves analyses. Interobserver agreement was assessed using kappa statistics and intraclass correlation coefficients (ICC).
Results
The qualitative diagnostic performance ranged from area under the curve (AUC) = 0.97 (95% CI: 0.91–1.00) to AUC = 0.99 (95% CI: 0.95–1.0). The quantitative diagnostic performance ranged from AUC = 0.82 (95% CI: 0.73–0.89) to AUC = 0.97 (95% CI: 0.91–0.99). Pairwise comparisons showed no statistical difference in diagnostic performance (all
p
> 0.0013, Bonferroni-corrected
p
< 0.0011). All five cases with disagreement among the readers were correctly diagnosed at quantitative analysis using ROI2. Interobserver agreement was excellent for both qualitative and quantitative analyses.
Conclusions
A single FSE T2-weighted Dixon sequence can be used to differentiate benign and malignant VCF with high diagnostic performance using both qualitative and quantitative analyses, which can provide complementary information.
Key Points
•
Qualitative analysis of a single FSE T2-weighted Dixon sequence yields high diagnostic performance and excellent observer agreement for differentiating benign and malignant compression fractures.
•
The same FSE T2-weighted Dixon sequence allows quantitative assessment with high diagnostic performance.
•
Quantitative data can readily be extracted from the FSE T2-weighted Dixon sequence and may provide complementary information to the qualitative analysis, which may be useful in doubtful cases.
Endovascular treatment (EVT) in acute ischemic stroke is effective in the late time window in selected patients. However, the frequency and clinical impact of procedural complications in the early ...versus late time window has received little attention.
We retrospectively studied all acute ischemic strokes from 2015 to 2019 receiving EVT in the Acute Stroke Registry and Analysis of Lausanne. We compared the procedural EVT complications in the early (<6 hours) versus late (6-24 hours) window and correlated them with short-term clinical outcome.
Among 695 acute ischemic strokes receiving EVT (of which 202 were in the late window), 113 (16.3%) had at least one procedural complication. The frequency of each single, and for overall procedural complications was similar for early versus late EVT (16.2% versus 16.3%,
=0.90). Procedural complications lead to a significantly less favorable short-term outcome, reflected by the absence of National Institutes of Health Stroke Scale improvement in late EVT (delta-National Institutes of Health Stroke Scale-24 hours, -2.5 versus 2,
=0.01).
In this retrospective analysis of consecutive EVT, the frequency of procedural complications was similar for early and late EVT patients but very short-term outcome seemed less favorable in late EVT patients with complications.
Purpose
We aimed to assess the impact of metal artifact reduction software (MARs) on image quality of gemstone spectral imaging (GSI) dual-energy (DE) cerebral CT angiography (CTA) after intracranial ...aneurysm clipping.
Methods
This retrospective study was approved by the institutional review board, which waived patient written consent. From January 2013 to September 2016, single source DE cerebral CTA were performed in 45 patients (mean age: 60 ± 9 years, male 9) after intracranial aneurysm clipping and reconstructed with and without MARs. Signal-to-noise (SNR), contrast-to-noise (CNR), and relative CNR (rCNR) ratios were calculated from attenuation values measured in the internal carotid artery (ICA) and middle cerebral artery (MCA). Volume of clip and artifacts and relative clip blurring reduction (rCBR) ratios were also measured at each energy level with/without MARs. Variables were compared between GSI and GSI-MARs using the paired Wilcoxon signed-rank test.
Results
MARs significantly reduced metal artifacts at all energy levels but 130 and 140 keV, regardless of clips’ location and number. The optimal rCBR was obtained at 110 and 80 keV, respectively, on GSI and GSI-MARs images, with up to 96% rCNR increase on GSI-MARs images. The best compromise between metal artifact reduction and rCNR was obtained at 70–75 and 65–70 keV for GSI and GSI-MARs images, respectively, with up to 15% rCBR and rCNR increase on GSI-MARs images.
Conclusion
MARs significantly reduces metal artifacts on DE cerebral CTA after intracranial aneurysm clipping regardless of clips’ location and number. It may be used to reduce radiation dose while increasing CNR.
To subjectively and objectively assess the impact of model-based iterative reconstruction(MBIR) on image quality in cerebral computed tomography angiography compared to adaptive statistical iterative ...reconstruction (ASIR).
107 patients (mean age: 58 ± 14 years) were included prior to (n = 38) and after (n = 69) intracranial aneurysm treatment. Images were acquired using a routine protocol and reconstructed with MBIR and ASIR. Image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios in the internal carotid and middle cerebral arteries were compared between MBIR and ASIR using the Wilcoxon signed-rank test. Additionally, two neuroradiologists subjectively assessed noise, artefacts, vessel sharpness and overall quality using a semi-quantitative assessment scale.
Objective assessment revealed that MBIR reduced noise (p < 0.0001) and additionally improved SNR (p < 0.0001) and CNR (p < 0.0001) compared to ASIR in untreated and treated patients. Subjective assessment revealed that in untreated patients, MBIR improved noise reduction, artefacts, vessel sharpness and overall quality relative to ASIR (p < 0.0001). In the treated groups, noise and vessel sharpness were improved (p < 0.0001) with no change in artefacts on images reconstructed with MBIR compared to ASIR.
MBIR significantly improves noise, SNR, CNR and vessel sharpness in untreated and treated patients with intracranial aneurysms. MBIR does not reduce artefacts generated by metallic devices following intracranial aneurysm treatment.
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