UNASSIGNED: Perfusion-weighted imaging (PWI; magnetic resonance imaging [MRI]) has been shown to provide valuable biological tumor information in uveal melanoma (UM). Clinically used semiquantitative methods do not account for tumor pigmentation and eye movement. We hypothesize that a quantitative PWI method that incorporates these, provides a more accurate description of tumor perfusion than the current clinical method. The aim of this study was to test this in patients with UM before and after radiotherapy.
UNASSIGNED: Perfusion-weighted 3T MRIs were retrospectively analyzed in 47 patients with UM before and after radiotherapy. Tofts pharmacokinetic modeling was performed to determine vascular permeability (Ktrans), extracellular extravascular space (ve), and reflux rate (kep). These were compared with semiquantitative clinical parameters including peak intensity and outflow percentage.
UNASSIGNED: The effect of tumor pigmentation on peak intensity and outflow percentage was statistically significant (P < 0.01) and relative peak intensity was significantly different between melanotic and amelanotic tumors (1.5 vs. 1.9, P < 0.01). Before radiotherapy, median tumor Ktrans was 0.63 min-1 (range = 0.06-1.42 min-1), median ve was 0.23 (range = 0.09-0.63), and median kep was 2.3 min-1 (range = 0.6-5.0 min-1). After radiotherapy, 85% showed a decrease in Ktrans and kep (P < 0.01). Changes in tumor pigmentation before and after radiotherapy were small and not significant (median increase in T1 of 33 ms, P = 0.55).
UNASSIGNED: Quantitative PWI parameters decreased significantly after radiotherapy and can therefore can serve as an early biomarker for treatment response assessment. However, due to the nonsignificant changes in tumor pigmentation before and after radiotherapy, the current semiquantitative method appears to be sufficiently sensitive for detection of changes in tumor perfusion.

UNASSIGNED: Popliteal artery entrapment syndrome remains difficult to diagnose. Meanwhile, our limited knowledge and understanding make treatment decisions complex. The list of differential diagnoses for exertional leg pain is broad. Oftentimes, patients exhibit confounding and coexisting diagnoses. However, accurate and rapid diagnosis of popliteal artery entrapment syndrome is essential to reduce potential lasting damage to the popliteal artery. A combination of clinical history, physical examination, ankle-brachial index, along with dynamic and static imaging such as duplex ultrasound, computed tomography angiogram, and magnetic resonance angiography, aids diagnosis. Surgical treatment may be definitive depending on the type of popliteal artery entrapment syndrome, but there have been recent advances in diagnostics with intravascular ultrasound and nonsurgical treatment with botulinum toxin type A. Further research is needed to standardize diagnostic criteria, uncover innovative diagnostic methods, and validate promising nonoperative treatment options.

Agenesis or hypoplasia of the internal carotid artery (ICA) may easily be confused with dissection or occlusion. We report a case of a 24-year-old female with complaint of acute left-hand hypoesthesia and a history of occasional intermittent numbness of her right hand with myoclonic jerking. Because previous imaging studies over 2 years were interpreted as occlusion of the left ICA secondary to carotid dissection, the treating physician had prescribed anticoagulant therapy. During transcranial Doppler (TCD) examination, the spectral waveform was unexpectedly normal, prompting a repeat review of all imaging due to the TCD results. Magnetic resonance angiography (MRA) revealed the same \"flame-like\" appearance of the ICA origin. Late-phase digital subtraction angiography showed a small caliber cervical ICA (occluded at the skull base). Computed tomography demonstrated absence of the carotid canal, confirming an absent intracranial portion of the ICA and establishing a correct diagnosis of left internal carotid hypoplasia. Vascular ultrasound and TCD examinations are noninvasive and inexpensive tools that can improve the interpretation and understanding of the clinical significance of other \"static\" radiographic tests (MRA, digital subtraction angiography ). An accurate diagnosis is essential to avoid risky, aggressive treatment, such as anticoagulation for an \"absent\" dissection.

OBJECTIVE: Recent innovations in radiological imaging have enabled the detection of micro-remnant niduses of arteriovenous malformations (AVMs) after gamma knife radiosurgery (GKS), which have not been previously perceptible. Herein, we focus on the difficulty of evaluating micro-remnant AVMs after GKS that are hardly perceptible on conventional examinations and propose integrating follow-up three-dimensional rotational angiography (3D-RA) in the previous gamma plan as a solution.
METHODS: We retrospectively searched NTT Medical Center Tokyo hospital database for patients with AVMs who underwent both two-dimensional digital subtraction angiography (2D-DSA) and 3D-RA as follow-up for GKS from February 2021 to January 2024. Patients with suspected nidus occlusion on the latest non-contrast-enhanced magnetic resonance angiography (NC-MRA) were included, and contrast-enhanced magnetic resonance angiography (CE-MRA), 2D-DSA, and 3D-RA were evaluated.
RESULTS: Twelve patients with 13 AVM sites were defined as having complete nidus occlusion on upfront NC-MRA. On 2D-DSA, seven AVM sites showed the presence of slight remaining AVMs based on the detection of remnant drainage veins, however the nidus was not detected in three cases. Nevertheless, 3D-RA detected micro-remnant niduses in all seven AVM sites, and four patients underwent re-GKS. Nine patients with ten AVM sites also underwent CE-MRA, and six AVM sites were diagnosed with radiation-induced parenchymal injury.
CONCLUSIONS: Importing the 3D-RA image into the treatment planning has the potential to be more helpful than NC-MRA or CE-MRA to detect micro-remnant AVMs and evaluate the true remnant volume, and may contribute to a more detailed treatment planning, thereby improving the results of GKS retreatment.

OBJECTIVE: We aimed to validate hyperintense vessel sign (HVS) on FLAIR imaging or posterior cerebral artery (PCA) laterality on MR angiography beyond 4.5 hours after stroke onset.
METHODS: Data from acute ischemic stroke patients with internal carotid or middle cerebral artery occlusion who underwent CT perfusion imaging at baseline, follow-up MR perfusion imaging and angiography within 30 hours after stroke, without effective recanalization on follow-up imaging, were analysed retrospectively. Patients were separately classified as high or low HVS (>5 or ≤5 slices of HVS), and PCA laterality positive or negative group. We compared core and penumbra volumes at follow-up imaging and neurological outcomes between high or low HVS group, and between PCA laterality positive or negative group.
RESULTS: Of 49 patients analyzed, four patients with artifacts were excluded and 45 were classified into high (n = 23) or low (n = 22) HVS group. High group had a smaller core volume (median 32 ml versus 109 ml, p = 0.004), larger penumbra volume at follow-up (68 ml versus 0 ml, p = 0.001), and better outcomes (modified Rankin Scale at three months, 3 versus 5, p = 0.03). For PCA laterality analysis, 1 patient with previously occluded PCA was excluded and 48 patients were classified as positive (n = 22) or negative (n = 26). Positive group had larger core volume (116 ml versus 37 ml), and no significant differences in penumbral volumes or outcomes.
CONCLUSIONS: Prominent HVS in later time was associated with small core volume, persistent penumbra volume and favorable outcomes.

Background Neoadjuvant chemoimmunotherapy (NACI) has significantly increased the rate of pathologic complete response (pCR) in patients with early-stage triple-negative breast cancer (TNBC), although predictors of response to this regimen have not been identified. Purpose To investigate pretreatment perfusion MRI-based radiomics as a predictive marker for pCR in patients with TNBC undergoing NACI. Materials and Methods This prospective study enrolled women with early-stage TNBC who underwent NACI at two different centers from August 2021 to July 2023. Pretreatment dynamic contrast-enhanced MRI scans obtained using scanners from multiple vendors were analyzed using the Tofts model to segment tumors and analyze pharmacokinetic parameters. Radiomics features were extracted from the rate constant for contrast agent plasma-to-interstitial transfer (or Ktrans), volume fraction of extravascular and extracellular space (Ve), and maximum contrast agent uptake rate (Slopemax) maps and analyzed using unsupervised correlation and least absolute shrinkage and selector operator, or LASSO, to develop a radiomics score. Score effectiveness was assessed using the area under the receiver operating characteristic curve (AUC), and multivariable logistic regression was used to develop a multimodal nomogram for enhanced prediction. The discrimination, calibration, and clinical utility of the nomogram were evaluated in an external test set. Results The training set included 112 female participants from center 1 (mean age, 52 years ± 11 [SD]), and the external test set included 83 female participants from center 2 (mean age, 47 years ± 11). The radiomics score demonstrated an AUC of 0.80 (95% CI: 0.70, 0.89) for predicting pCR. A nomogram incorporating the radiomics score, grade, and Ki-67 yielded an AUC of 0.86 (95% CI: 0.78, 0.94) in the test set. Associations were found between higher radiomics score (>0.25) and tumor size (P < .001), washout enhancement (P = .01), androgen receptor expression (P = .009), and programmed death ligand 1 expression (P = .01), demonstrating a correlation with tumor immune environment in participants with TNBC. Conclusion A radiomics score derived from pharmacokinetic parameters at pretreatment dynamic contrast-enhanced MRI exhibited good performance for predicting pCR in participants with TNBC undergoing NACI, and could potentially be used to enhance clinical decision making. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Rauch in this issue.

OBJECTIVE: This study used two-dimensional time-of-flight magnetic resonance venography (2D TOF MRV) to show the shape of the transverse sinus and to determine whether there is a correlation between the asymmetry of the transverse sinus morphology and the intraocular pressure (IOP) of the two eyes.
METHODS: In this study, 63 male and 42 female volunteers were included. Those with obvious neurological diseases and eye diseases were excluded. According to the morphology of the transverse sinus scanned with 2D TOF MRV, subjects were divided into five groups. The IOP of the volunteers was measured separately.
RESULTS: The difference between group I and group V is statistically significant (Z = 6.78, P < 0.01). Statistically, significant differences also existed among the IOP of each group, including the mean values of both eyes and the difference between the right eye and the left eye. The asymmetry of the transverse sinus maintained a negative correlation with the right IOP (r = 0.51, P < 0.01) and the difference between the right eye and the left eye (r = 0.79, P < 0.01). The asymmetry and the left IOP had no statistical correlation.
CONCLUSIONS: The preliminary conclusion of this study is that if one side of the transverse sinus is thicker, the drainage-related ocular veins are relatively coarser, and the IOP is relatively lower. The 2D TOF MRV examination can be used as an examination to show the shape of the transverse sinus. It is a display method to provide a feasible means of inspection for a reasonable interpretation.

OBJECTIVE: Cerebral venous and sinus thrombosis (CVST) leads to perfusion abnormality in the brain. Our aim was to assess perfusion abnormalities in the center and periphery of the parenchymal lesion in CVST patients and correlate with the clinical outcome.
METHODS: Dynamic susceptibility contrast (DSC) perfusion imaging was performed in patients with CVST. Relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and mean transit time (MTT) values were obtained in the center and periphery of the parenchymal lesion.
RESULTS: A total of 30 consecutive patients of CVST were included in the study. Parenchymal lesion was present in 21 (70%) patients. In rest 9, perfusion map was showing some abnormality although conventional MRI was normal. Mean rCBV and MTT were increasing from periphery of the lesion to the center (rCBV 69.93 ± 29.79 at periphery (PL2) to 92.49 ± 32.07 at center of the lesion and 69.19 ± 25.52 at normal appearing contralateral brain parenchyma (NABP). MTT 11.83 ± 3.76 at periphery (PL2) to 15.27 ± 5.49 at center of the lesion and 10.63 ± 3.37 at NABP). rCBV and MTT from abnormal perfusion areas from 9 patients without parenchymal abnormalities are 92.89 ± 17.76 and 15.92 ± 3.66 respectively.
CONCLUSIONS: There is an increasing trend of MTT and rCBV from periphery to center of the parenchymal lesion. MTT is the most consistent parameter to be abnormal in patients of CVST even in patients without parenchymal lesion. Residual neurological deficit was found in patients with increased rCBV and having large hemorrhagic infarct.

BACKGROUND: Radiosurgery plays an important role as a treatment modality for intracranial meningiomas. Perfusion MR imaging can be performed by using arterial spin-labeling (ASL) which is a relatively new and advanced technique.
OBJECTIVE: To assess the changes in perfusion parameters on ASL perfusion MRI in intracranial meningioma after radiosurgery and correlate with histopathological grade of meningioma.
METHODS: In this Prospective study done at the our institute over a period of 20 months (Jan 2016-Aug 2017), patients with intracranial meningiomas had perfusion MRI with ASL sequence on GE Optima 450W®, 1.5T MRI (GE Medical Systems) prior to GKT and at 6 months after GKT were included in the study.
RESULTS: Twenty-seven patients were included in this study. Mean cerebral blood flow (CBF) was higher in angiomatous meningiomas. Though mean values of average CBF, maximum, minimum, and SD derived from the ASL MR perfusion were relatively higher in post GKT group as compared to those obtained in pre-GKT but it was not clinically significant. Mean baseline volume of whole cohort was 5.71 cm3 and decreased significantly post GKT in a follow up of 6 months to 5.59 cm3 (P value 0.0018). On comparing volumes of primary and secondary group, volumes were not found be significantly decreased in primary group (P value = 0.1361), 0.1361), but significantly reduced in secondary group (7.13 vs 7.034 cm3) (P value of = 0.0038).
CONCLUSIONS: Our preliminary observations support ASL as a sensitive MRI sequence for the evaluation of meningioma perfusion patterns.

A girl in middle childhood presented with glaucoma in her right eye along with segmental haemangiomas on the right side of the face and neck. Magnetic resonance angiography of the brain showed hypoplasia of the right internal carotid artery, leading to the diagnosis of posterior fossa malformations, haemangioma, arterial anomalies, cardiac defects and eye abnormalities (PHACE) syndrome. High-definition anterior segment ocular coherence tomography (AS-OCT) of the right eye showed an absence of Schlemm\'s canal and a hyperreflective membrane over the trabecular meshwork. The presence of this angle dysgenesis on AS-OCT, a novel finding in this disease, explained the elevated intraocular pressure in the right eye. The embryological basis for the development of angle dysgenesis might help better understand the pathogenesis of PHACE syndrome.