Changes In Perfusion Patterns Research Articles

Alteration of intracranial blood perfusion in temporal lobe epilepsy, an arterial spin labeling study

BackgroundA critical necessity before surgical resection in mesial temporal lobe epilepsy (mTLE) is lateralizing the seizure focus in the temporal lobe. This study aimed to investigate the differences in perfusion pattern changes in right and left mTLE. Methods42 mTLE patients (22 left and 20 right mTLE) and 14 controls were surveyed with pulsed arterial spin labeling at 3.0 T. The mean cerebral blood flow (CBF) and asymmetry index (AI) were calculated in the bilateral temporal lobe, amygdala, hippocampus, parahippocampus, and nine bilateral vascular territories ROIs. The alterations in whole-brain CBF were identified using statistical parametric mapping (SPM). ResultsCBF decreased in ipsilateral sides in both epilepsy subcohorts, with right mTLE showing a significant difference in most ROIs while left mTLE exhibiting no significant change. CBF comparison of left mTLE and controls showed a significant drop in ROI analysis in left middle temporal and left intermediate posterior cerebral artery and in AI analysis in parahippocampus, distal anterior cerebral artery, distal middle cerebral artery, and intermediate anterior cerebral artery. CBF hypoperfusion was seen in ROI analysis in the left intermediate anterior cerebral artery, left middle temporal, right middle temporal, left superior temporal in the right mTLE compared to controls. Left mTLE CBF differed significantly from right mTLE CBF in right distal middle cerebral artery ROI and AI of proximal middle cerebral artery. ConclusionOur result revealed that mTLE affects extratemporal regions and both mTLE subcohorts with different perfusion patterns, which may enhance the performance of preoperative MRI assessment in lateralization procedures.

Prediction of the trans-stenotic pressure gradient with arteriography-derived hemodynamic features in patients with idiopathic intracranial hypertension

The pathogenesis of idiopathic intracranial hypertension (IIH) is attributed to segmental stenosis of the venous sinus. The current treatment paradigm requires a trans-stenotic pressure gradient of ≥8 mmHg or ≥6 mmHg threshold. This study aimed to develop a machine learning screening method to identify patients with IIH using hemodynamic features. A total of 204 venous manometry instances (n = 142, training and validation; n = 62, test) from 135 patients were included. Radiomic features extracted from five arteriography perfusion parameter maps were selected using least absolute shrinkage and selection operator and then entered into support vector machine (SVM) classifiers. The Thr8-23-SVM classifier was created with 23 radiomic features to predict if the pressure gradient was ≥8 mmHg. On an independent test dataset, prediction sensitivity, specificity, accuracy, and AUC were 0.972, 0.846, 0.919, and 0.980, respectively (95% confidence interval: 0.980–1.000). For the 6 mmHg threshold, thr6-28-SVM incorporated 28 features, and its sensitivity, specificity, accuracy, and AUC were 0.923, 0.956, 0.935, and 0.969, respectively (95% confidence interval: 0.927–1.000). The trans-stenotic pressure gradient result was associated with perfusion pattern changes, and SVM classifiers trained with arteriography perfusion map-derived radiomic features could predict the 8 mmHg and 6 mmHg dichotomized trans-stenotic pressure gradients with favorable accuracy.

Remodeling of Aortic Configuration and Abdominal Aortic Branch Perfusion After Endovascular Repair of Acute Type B Aortic Dissection: A Computed Tomographic Angiography Follow-Up.

Background: Thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD) induces false lumen (FL) thrombosis, promotes favorable aortic remodeling, and makes an impact on abdominal aortic branch perfusion patterns. However, little is known about the long-term fate of aortic remodeling and abdominal aortic branch perfusion after TEVAR for TBAD and the effect of FL thrombosis status on these changes.Materials and methods: Between January 2014 and May 2021, 59 enrolled patients with acute TBAD were treated with TEVAR and had post-operative or follow-up images. Pre-operative, post-operative, and latest follow-up CT angiography (CTA) data were analyzed for the largest diameter of true lumen (TL), FL, and transaorta and for the FL thrombosis status on the stented thoracic aorta, unstented thoracic aorta, and abdominal aorta. Abdominal aorta perfusion patterns were characterized.Results: The mean follow-up period was 17.1 months. In the stented thoracic aorta, average TL diameters increased, average FL diameters decreased, and average transaortic diameters did not change; 82.6% of the patients had either a stable or shrinking transaortic size and 87% of the patients achieved total FL thrombosis. In the unstented thoracic aorta, average TL diameters increased, transaortic growth and no changes occurred in 39.1 and 45.7% of the patients, respectively, and complete FL thrombosis was present in 50% of the patients. In the abdominal aorta, average FL and transaortic diameters increased, aorta was expanded in 52.2% of the patients, and FL remained patent in 65.2% of the patients. Of the 354 branches, 37 branches (10.5%) exhibited changes in perfusion patterns, 22 branches (6.2%) demonstrated an increased TL perfusion, and 15 branches (4.2%) had an increased FL contribution. Compared with patent or partially thrombosed FL, complete FL thrombosis was accompanied by a bigger decrease in FL diameters, a larger increase in TL diameters, and a higher percentage of abdominal branch TL perfusion.Conclusions: In majority of the patients, TEVAR stabilized the size of the stented thoracic aorta, namely TL expansion and FL obliteration. However, abdominal aortic FL remained patent FL, and it was expanded with the resultant transaortic growth over a long follow-up period. Abdominal aortic branch perfusion patterns remained largely stable after TEVAR. The failure to achieve FL thrombosis negatively affects the remodeling of a contagious abdominal aortic dissection.

Remodeling of abdominal aortic branch perfusion after thoracic endovascular aortic repair for aortic dissections

The fate of the abdominal aorta and its branches after thoracic endovascular aortic repair for aortic dissection (TEVAR-AD) has not been studied. The objective of this study was to describe the midterm changes in abdominal aortic branch perfusion after TEVAR-AD. A retrospective analysis of TEVAR-AD at a single institution from December 1, 2008, to March 31, 2015, was performed. Computed tomography angiography (CTA) images were reviewed to characterize the perfusion pattern changes of the celiac, superior mesenteric, inferior mesenteric, bilateral renal, and common iliac arteries. Risk factors associated with branch interventions were identified. During the study period, 68 patients underwent TEVAR-AD, 46 of whom had pre-TEVAR and post-TEVAR CTA images available for review. For post-TEVAR CTA, the most recent scans were selected for analysis. The mean period between CTA studies was 371days. Indications for TEVAR-AD were persistent pain (41%), malperfusion (15%), rupture (6%), and aneurysmal degeneration (33%). Twenty-five patients (54%) were treated during the acute phase (<14days). All patients had dissections extending to the paravisceral aorta. Of the 304 abdominal aortic branches analyzed, 8 required intervention (2.6%). Branch events requiring intervention included malperfusion (two) and aneurysms involving the branches (three). No intervention was performed for one asymptomatic inferior mesenteric artery occlusion. Of the remaining 295 branches, changes in perfusion patterns were observed in 16 (5.4%). Twelve branches (75%) demonstrated an increased true lumen contribution to perfusion. Four branches (25%) had increased false lumen contribution, without clinical evidence of malperfusion. Patients requiring branch interventions were more likely to have severe chronic kidney disease (P= .012) and more extensive aortic zone coverage during TEVAR (P= .003). On multivariable Cox proportional hazards analysis, coverage of four or more zones during TEVAR-AD was associated with branch intervention (odds ratio, 6.44; 95% confidence interval, 1.01-40.8). The estimated intervention-free patency of the abdominal aortic branches was 89% at 5years. Perfusion patterns of abdominal aortic branches remain largely stable after TEVAR-AD. The need for branch intervention is rare and associated with extensive aortic coverage.

Cerebral perfusion alterations in epileptic patients during peri-ictal and post-ictal phase: PASL vs DSC-MRI

Non-invasive pulsed arterial spin labeling (PASL) MRI is a method to study brain perfusion that does not require the administration of a contrast agent, which makes it a valuable diagnostic tool as it reduces cost and side effects. The purpose of the present study was to establish the viability of PASL as an alternative to dynamic susceptibility contrast (DSC-MRI) and other perfusion imaging methods in characterizing changes in perfusion patterns caused by seizures in epileptic patients. We evaluated 19 patients with PASL. Of these, the 9 affected by high-frequency seizures were observed during the peri-ictal period (within 5hours since the last seizure), while the 10 patients affected by low-frequency seizures were observed in the post-ictal period. For comparison, 17/19 patients were also evaluated with DSC-MRI and CBF/CBV. PASL imaging showed focal vascular changes, which allowed the classification of patients in three categories: 8 patients characterized by increased perfusion, 4 patients with normal perfusion and 7 patients with decreased perfusion. PASL perfusion imaging findings were comparable to those obtained by DSC-MRI. Since PASL is a) sensitive to vascular alterations induced by epileptic seizures, b) comparable to DSC-MRI for detecting perfusion asymmetries, c) potentially capable of detecting time-related perfusion changes, it can be recommended for repeated evaluations, to identify the epileptic focus, and in follow-up and/or therapy-response assessment.

Composite SISCOM Perfusion Patterns in Right and Left Temporal Seizures

To compare composite subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance imaging (also known as SISCOM) patterns between right and left medial temporal-onset seizures to document neuroanatomical involvement in perfusion patterns. A retrospective comparative survey. Epilepsy monitoring unit in a tertiary care referral center. Subjects with temporal lobe epilepsy (TLE) who underwent ictal single-photon emission computed tomography studies. Comparison of ictal perfusion pattern changes in subjects with right and left temporal seizures. Composite subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance images showed similar regions of hyperperfusion change in the ipsilateral anteromedial temporal-corpus striatum-insula region in both groups. In the midbrain reticular formation, there was a significant difference in hyperperfusion between the left and right TLE groups. In addition, the right, but not the left, TLE group shows contralateral hypoperfusion of the temporoparietal junction. While anteromedial temporal-corpus striatum-insula perfusion patterns are similar, there are brainstem and hemispheric perfusion pattern differences in right and left TLE seizures, confirming pathophysiological differences between the groups. These findings help define neuronal network involvement in TLE seizures, and may explain the differences in clinical symptoms of right and left TLE seizures.

Changes of arterial blood flow patterns during infusion chemotherapy, as monitored by intra-arterially injected technetium 99m macroaggregated albumin.

Arterial catheter tip position and arterial flow was monitored by intra-arterial infusion of 99Tcm macroaggregated albumin in patients treated by intra-arterial chemotherapy. Variations in arterial flow pattern as monitored by macroaggregated albumin perfusion studies were encountered in 16 patients without apparent change in the catheter position as monitored by arteriographic and/or radiographic examinations. Possible mechanisms causing changes in arterial flow pattern include: (a) development of collateral circulation, (b) arterial spasm, (c) progressive arteritis causing thrombi with or without associated spasm, and (d) laminar flow. It is important to recognise that changes in perfusion patterns are not always accompanied by change in the position of the arterial catheter.