AJNR. American journal of neuroradiology最新文献

Background and purpose: Percutaneous cement augmentation has been reported as an effective salvage procedure for frail patients with spinal instrumentation failure, such as screw loosening, hardware breakage, cage subsidence, and fractures within or adjacent to stabilized segments. Favorable results were reported during a median follow-up period of 16 months in a retrospective analysis of 31 consecutive procedures performed in 29 patients. In the present study, the long-term effectiveness of this treatment in avoiding or postponing revision surgery is reported.

Materials and methods: Clinical and radiologic data of our original cohort of patients were retrospectively collected and reviewed to provide an extended follow-up assessment. The need for revision spinal surgery was assessed as the primary outcome, and the radiologic stability of the augmented spinal implants was considered as the secondary outcome.

Results: An extended radiologic follow-up was available in 27/29 patients with an average of 50.9 months. Overall, 18 of 27 (66.7%) patients, originally candidates for revision surgery, avoided a surgical intervention after a cement augmentation rescue procedure. In the remaining patients, the average interval between the rescue cement augmentation and the revision surgery was 22.5 months. Implant mobilization occurred in 2/27 (7.4%) patients; rod breakage, in 1/27 (3.7%); a new fracture within or adjacent to the instrumented segment occurred in 4/27 (14.8%) patients; and screw loosening at rescued levels occurred in 5/27 (18.5%) patients.

Conclusions: In this cohort, cement augmentation rescue procedures were found to be effective in avoiding or postponing revision surgery during long-term follow-up.

Background and purpose: A cleftlike nonenhancing hypointensity was observed repeatedly in the pituitary gland at the adenohypophysis/neurohypophysis border on contrast-enhanced 3D fat-saturated T1-MPRAGE using clinical 7T MRI. Our primary goal was to assess the prevalence of this finding. The secondary goals were to evaluate the frequency of other incidental pituitary lesions, MRI artifacts, and their effect on pituitary imaging on the contrast-enhanced 3D fat-saturated T1 MPRAGE at 7T.

Materials and methods: One hundred patients who underwent 7T neuroimaging between October 27, 2021, and August 10, 2023, were included. Each case was evaluated for cleftlike pituitary hypointensity, pituitary masses, and artifacts on contrast-enhanced 3D fat-saturated T1 MPRAGE. Follow-up examinations were evaluated if present. The average prevalence for each finding was calculated, as were descriptive statistics for age and sex.

Results: A cleftlike hypointensity was present in 66% of 7T MRIs. There were no significant differences between the "cleftlike present" and "cleftlike absent" groups regarding sex (P = .39) and age (P = .32). The cleftlike hypointensity was demonstrated on follow-up MRIs in 3/3 patients with 7T, 1/12 with 3T, and 1/5 with 1.5T. A mass was found in 22%, while 75% had no mass and 3% were indeterminate. A mass was found in 18 (27%) of the cleftlike present and 4 (13%) of the cleftlike absent groups. The most common mass types were Rathke cleft cyst in 7 (31.8%) patients, "Rathke cleft cyst versus entrapped CSF" in 6 (27.3%), and microadenoma in 6 (22.2%) in the cleftlike present group. There were no significant differences in the mass types between the cleftlike present and cleftlike absent groups (P = .23). Susceptibility and/or motion artifacts were frequent using contrast-enhanced 3D fat-saturated T1 MPRAGE (54%). Artifact-free scans were significantly more frequent in the cleftlike present group (P = .03).

Conclusions: A cleftlike nonenhancing hypointensity was frequently seen on the contrast-enhanced 3D fat-saturated T1 MPRAGE images at 7T MRI, which most likely represents a normal embryologic Rathke cleft remnant and cannot be seen in lower-field-strength MRIs. Susceptibility and motion artifacts are common in the sella. They may affect image quality, and the artifacts at 7T may lead to an underestimation of the prevalence of the Rathke cleft and other incidental findings.

Four distinct vascular anomalies can be seen to affect the brain on fetal imaging: vein of Galen malformations, nongalenic arteriovenous pial fistulas, dural sinus malformations, and intracranial venous malformations. These congenital disorders affect the arteries and veins of the developing brain and are rarely seen beyond the neonatal stage. The 4 fetal cerebrovascular anomalies are associated with quite disparate natural histories and prognoses. MRI plays a pivotal role in the evaluation of fetuses with these conditions because of its ability to definitively establish the diagnosis, to detect subtle parenchymal injuries, to delineate the course of abnormal vessels in detail and to some extent the nature of vascular flow, and to identify ischemic, thrombotic, and hemorrhagic complications. Recently, an investigational transuterine embolization procedure targeted at treating fetuses with vein of Galen malformations who are at high risk for neonatal decompensation has emerged as a promising alternative to expectant management and postnatal embolization, with imaging being used to identify suitable patients for the intervention and in preprocedural planning. This manuscript reviews the essential imaging and clinical features of these 4 fetal neurovascular anomalies and underscores the practical aspects related to counseling, prognosis, and the multidisciplinary management of these entities.

Background and purpose: The cerebral metabolic rate of oxygen (CMRO₂) is considered a robust marker of the infarct core in ¹⁵O-tracer-based PET. We aimed to delineate the infarct core in patients with acute ischemic stroke by using commonly used relative CBF (rCBF) < 30% and oxygen metabolism parameter of CMRO₂ on CT perfusion in comparison with pretreatment DWI-derived infarct core volume.

Materials and methods: Patients with acute ischemic stroke who met the inclusion criteria were recruited. The CMRO₂ and CBF maps in CT perfusion were automatically generated by using postprocessing software. The infarct core volume was quantified with relative cerebral metabolic rate of oxygen (rCMRO₂) <20% -30% and rCBF <30%. The optimal threshold was defined as those that demonstrated the smallest mean absolute error, lowest mean infarct core volume difference, narrowest 95% limit of agreement, and largest intraclass correlation coefficient (ICC) against the DWI.

Results: This study included 76 patients (mean age ± standard deviation, 69.97 ± 12.15 years, 43 men). The optimal thresholds of rCMRO₂ <26% resulted in the lowest mean infarct core volume difference, narrowest 95% limit of agreement, and largest ICC among different thresholds. Bland-Altman analysis demonstrated a volumetric bias of 1.96 mL between DWI and rCMRO₂ <26%, whereas in cases of DWI and rCBF <30%, the bias was notably larger at 14.10 mL. The highest correlation was observed for rCMRO₂ <26% (ICC = 0.936), whereas rCBF <30% showed a slightly lower ICC of 0.934.

Conclusions: CT perfusion-derived CMRO₂ is a promising parameter for estimating the infarct core volume in patients with acute ischemic stroke.

Background and purpose: The glymphatic (glia-lymphatic) system is a paravascular pathway for the clearance of waste metabolites including amyloid β from the brain. Serial T1 relaxation time measurements after the intrathecal injection of gadolinium-based contrast agents facilitate the analysis of the temporal dynamics that may be different in patients with spontaneous intracranial hypotension (SIH) and those without SIH.

Materials and methods: 3D T1-weighted magnetization-prepared 2 rapid gradient echo sequences were acquired in 4 patients with SIH with proved CSF leaks and 12 patients without SIH before, 2-4, 6-8, and 24-48 hours after intrathecal gadobutrol injection. MR scans were warped to the Montreal Neurological Institute space and serial scans were coregistered. T1 relaxation times were measured in predefined ROIs including the subarachnoid space, cortex, white matter, and cervical lymph nodes.

Results: In the subarachnoid space and cortex, T1 relaxation times decreased after 2-4 and 6-8 hours before they increased again. In contrast, in the white matter of the temporal lobe T1 relaxation time still decreased after 24-48 hours. There was a striking difference in patients with SIH who did not show a clear contrast distribution within the brain parenchyma.

Conclusions: T1 relaxation time curves are compatible with a convective flow driven by arterial pulsations via paravascular spaces surrounding penetrating arteries into the brain's interstitial fluid in the deep white matter. Different curves in patients with SIH and those without SIH indicate that the CSF pressure also impacts the temporal kinetics of the glymphatic system.

Giant cell arteritis (GCA) is the most common primary large vessel systemic vasculitis in the Western World. Even though the involvement of scalp and intracranial vessels has received much attention in the neuroradiology literature, GCA, being a systemic vasculitis, can involve multiple other larger vessels including the aorta and its major head and neck branches. Herein, the authors present a pictorial review of the various cranial, extracranial, and orbital manifestations of GCA. An increased awareness of this entity may help with timely and accurate diagnosis, helping expedite therapy and preventing serious complications.

Background and purpose: Autoimmune rheumatic diseases (AIRD) can cause intracranial artery stenosis (ICAS) and lead to stroke. This study aimed to characterize patients with ICAS associated with AIRD.

Materials and methods: Utilizing data from a high-resolution magnetic resonance imaging (HRMRI) database, we retrospectively reviewed AIRD patients with ICAS. Stratification into vasculitis, atherosclerosis, and mixed athero-vasculitis subtypes was based on imaging findings, followed by a comparative analysis of clinical characteristics and outcomes across these subgroups.

Results: Among 139 patients (45.1±17.3 years; 64.7% females), 56 (40.3%) were identified with vasculitis, 57 (41.0%) with atherosclerosis, and 26 (18.7%) with mixed athero-vasculitis. The average interval from AIRD-onset to HRMRI was 5 years. Patients with vasculitis presented with a younger age of AIRD-onset (34.5±19.4 years), nearly ten years earlier than other groups (P=0.010), with a higher artery occlusion incidence (44.6% vs. 21.1% and 26.9%, P=0.021). Patients with atherosclerosis showed the highest cardiovascular risk factor prevalence (73.7% vs. 48.2% and 61.5%, P=0.021) but lower intracranial artery wall enhancement instances (63.2% vs. 100% in others, P<0.001). The mixed athero-vasculitis group, predominantly male (69.2% vs. 30.4% and 25.6%, P<0.001), exhibited the most arterial involvement (5 arteries per person vs. 3 and 2, P=0.001). Over an average 21-month follow-up, 23 (17.0%) patients experienced stroke events, and 8 (5.9%) died, with the mixed athero-vasculitis group facing the highest risk of stroke events (32.0%) and the highest mortality (12.0%).

Conclusions: Intracranial arteries are injured and lead to heterogeneous disease courses when exposed to AIRD and cardiovascular risk factors. While atherosclerosis acceleration is common, vasculitis may further contribute to early-developed occlusion and multiple artery involvement. Varied intracranial arteriopathies may result in different outcomes.

Abbreviations: ICAS = intracranial artery stenosis; AIRD = Autoimmune rheumatic diseases; HRMRI = high-resolution magnetic resonance imaging.

Background and purpose: Cochlear implant surgery is performed commonly through the facial recess via the round window (RW) approach. This study aims to evaluate the utility of reformatting the pre-operative CT temporal bone scan into a CT facial recess view in alerting surgeons to a potentially difficult surgery with poorly visualized round window.

Materials and methods: This is a retrospective study of 41 patients (43 ears), who had undergone cochlear implant surgery. Intraoperative findings of round window position relative to 2nd genu-mastoid portion of facial nerve, and round window membrane orientation were recorded by the surgeons. Pre-operative CTs were analyzed by two radiologists in axial and a reformatted facial recess plane that simulates the surgeon's view via the facial recess. Radiological assessment markers include the facial nerve-chorda tympani nerve width (FN-CTN) measured 1.2mm inferior to the exit point of the chorda tympani nerve into the tympanic cavity, round window position relative to 2^nd genu-mastoid segment of the facial nerve and RW membrane's angle from the vertical axis.

Results: The best predictor for difficult round window intraoperative visibility is the RW position relative to the 2nd genu-mastoid segment of the facial nerve lying lateral to it on CT facial recess reformatted images. A RW that lies partially to completely posterior to the posterior border of the 2^nd genu-mastoid segment of the facial nerve had up to 55.6% risk of encountering difficult access, while those positioned anterior to or partially anterior to the anterior edge of the 2^nd genu-mastoid segment of the facial nerve had 0% risk of difficult access (p<0.05). There are substantial agreements in the intra-rater (Kappa=0.751, p<0.001) and inter-rater reliability (Kappa= 0.698, p<0.001). There is no significant association between surgical difficulty and facial nerve-chorda tympani distance or RW angle (p>0.05).

Conclusions: Identification of round window positions in the reformatted CT facial recess view is a useful tool in predicting potentially difficult round window access in cochlear implant surgery.

Abbreviations: RW= Round window, FN-CTN= facial nerve to chorda tympani nerve width.

Background: Beginning in 2006, neuroradiologists became increasingly aware of the risk of nephrogenic system fibrosis (NSF) when patients suffering from chronic kidney disease (CKD) received gadolinium-based contrast agents (GBCAs) in conjunction with MRI scans. Radiology practices began withholding GBCAs from MRI patients with substantial CKD and instated a variety of safety measures to ensure that these individuals did not inadvertently receive GBCAs. As a result, the worldwide incidence of NSF was dramatically reduced. Since that time, a wealth of research on NSF and its etiology has found few unconfounded cases associated with those GBCAs categorized as Group II agents by the American College of Radiology.

Methods: In 2023 and 2024, members of the American Society of Neuroradiology (ASNR) Standards and Guidelines Committee reviewed new research evidence on GBCA safety and its relevance to current MRI contrast administration guidelines for patients with CKD. This focused on systematic reviews and meta-analyses conducted during the past five years. Upon consideration of this literature, recommendations for administration of GBCAs to patients with CKD were formulated.

Key message: For neuroimaging applications, the ASNR recommends that Group II GBCAs no longer be withheld in patients with CKD when these agents are medically indicated for diagnosis. Moreover, if Group II GBCAs are exclusively used in an MRI practice, other safety measures such as checking renal function or querying patients about chronic kidney disease can be discontinued.

Abbreviations: ACR = American College of Radiology; ASNR = American Society of Neuroradiology; CKD = chronic kidney disease; GBCA = gadolinium-based contrast agent; NSF = nephrogenic systemic fibrosis.

Background and purpose: Low back pain commonly causes disability, often managed with conservative image-guided interventions before surgery. Research has documented racial disparities with these and other non-pharmacologic treatments. We posited that individual chart reviews may provide insight into the disparity of care types through documented patient/provider discussions and their effect on treatment plans.

Materials and methods: This retrospective analysis involved adults newly diagnosed with low back pain within a large Utah healthcare system. The primary outcome was the association of provider and patient variables with the frequency of image-guided interventions received within one year of low back pain diagnosis between White/non-Hispanic and underrepresented minority cohorts. Secondary outcomes were receipt of additional treatment types (physical therapy and lumbar surgery), time to any treatment, time to image-guided intervention, and discussion/receipt of therapy between cohorts within one year of diagnosis.

Results: Among 812 subjects (59% White/non-Hispanic and 41% underrepresented minority), more White/non-Hispanic patients had at least one image-guided intervention within 12 months compared to underrepresented minority patients (7.2% vs. 12.5%, p = .001), despite underrepresented minorities having higher presenting pain scores (64.5% vs. 49.3%; pain intensity > 5, p = .001). Underrepresented minority patients more often saw generalists (71.7% vs. 52.6%, p < .001) and advanced practice clinician providers (33.6% vs. 25.6%, p < .02) compared to the White/non-Hispanic cohort. Both cohorts were referred to a specialist at the same rate (17.7% vs. 19.8%, p = .20); however, referral completion was noted less often (60.4% vs. 77.7%, p = .02) and took longer to complete in underrepresented minority patients (54 vs. 27.5; mean day, p = .003).

Conclusions: Underrepresented minority patients had more severe low back pain on presentation but received image-guided interventions less often than White/non-Hispanic patients. While there may be systematic provider barriers, such as absence of a decision-making discussion, data do not support provider bias as a contributing factor to differences in receipt of image-guided interventions. Non-medical barriers to referral completion should be further investigated to improve access to more specialized low back pain care.

Abbreviations: IGI = image-guided intervention; LBP = low back pain; URM = underrepresented minority; WNH = White/non-Hispanic; ICC = intraclass correlation coefficient.