Erratum: Acute Acquired Metabolic Encephalopathy Based on Diffusion MRI.

This corrects the article on p. 2034 in vol. 22, PMID: 34564957.

Monitoring Radiation Doses during Diagnostic and Therapeutic Neurointerventional Procedures: Multicenter Study for Establishment of Reference Levels.

PURPOSE: To assess patient radiation doses during diagnostic and therapeutic neurointerventional procedures from multiple centers and propose dose reference level (RL). MATERIALS AND METHODS: Consecutive neurointerventional procedures, performed in 22 hospitals from December 2020 to June 2021, were retrospectively studied. We collected data from a sample of 429 diagnostic and 731 therapeutic procedures. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time (FT), and total number of image frames (NI) were obtained. RL were calculated as the 3rd quartiles of the distribution. RESULTS: Analysis of 1160 procedures from 22 hospitals confirmed the large variability in patient dose for similar procedures. RLs in terms of DAP, CAK, FT, and NI were 101.6 Gy·cm2, 711.3 mGy, 13.3 minutes, and 637 frames for cerebral angiography, 199.9 Gy·cm2, 3,458.7 mGy, 57.3 minutes, and 1,000 frames for aneurysm coiling, 225.1 Gy·cm2, 1,590 mGy, 44.7 minutes, and 800 frames for stroke thrombolysis, 412.3 Gy·cm2, 4,447.8 mGy, 99.3 minutes, and 1,621.3 frames for arteriovenous malformation (AVM) embolization, respectively. For all procedures, the results were comparable to most of those already published. Statistical analysis showed male and presence of procedural complications were significant factors in aneurysmal coiling. Male, number of passages, and procedural combined technique were significant factors in stroke thrombolysis. In AVM embolization, a significantly higher radiation dose was found in the definitive endovascular cure group. CONCLUSION: Various RLs introduced in this study promote the optimization of patient doses in diagnostic and therapeutic interventional neuroradiology procedures. Proposed 3rd quartile DAP (Gy·cm2) values were 101.6 for diagnostic cerebral angiography, 199.9 for aneurysm coiling, 225.1 for stroke thrombolysis, and 412.3 for AVM embolization. Continual evolution of practices and technologies requires regular updates of RLs.

Acute Acquired Metabolic Encephalopathy Based on Diffusion MRI.

Metabolic encephalopathy is a critical condition that can be challenging to diagnose. Imaging provides early clues to confirm clinical suspicions and plays an important role in the diagnosis, assessment of the response to therapy, and prognosis prediction. Diffusion-weighted imaging is a sensitive technique used to evaluate metabolic encephalopathy at an early stage. Metabolic encephalopathies often involve the deep regions of the gray matter because they have high energy requirements and are susceptible to metabolic disturbances. Understanding the imaging patterns of various metabolic encephalopathies can help narrow the differential diagnosis and improve the prognosis of patients by initiating proper treatment regimen early.

Staged carotid artery stenting in patients with severe carotid stenosis: Multicenter experience.

Cerebral hyperperfusion syndrome (CHS) is serious complication after carotid artery stenting (CAS) caused by decreased cerebral vasoreactivity (CVR) due to long standing hypoperfusion of the brain. We hypothesized that partial dilatation of carotid stenosis would allow the recovery of CVR, and prevent CHS when definitive angioplasty with stent is performed afterward. In this study, we aimed to evaluate the safety and efficacy of staged CAS in patients with severe carotid artery stenosis with evident hemodynamic compromise in regard to preventing hyperperfusion syndrome. From January 2005 to February 2016, 53 patients with 55 severe carotid artery stenosis lesions showing decreased CVR and/or cerebral basal flow at the perfusion studies underwent staged CAS in three institutes. The procedure consisted of initial partial balloon angioplasty (BA), recovery period, and delayed definitive stenting (DS). We analyzed immediate results, complications, recoil and CHS related to staged CAS. We experienced no symptomatic manifestation of CHS except self-limited headache after the procedures. The median of intervals between BA and DS stages were 10 days. There was no case of severe recoil during the interval between BA and DS stage. Where perfusion imaging data was available, hyperperfusion was present in three and one patients after BA and DS stage, respectively, with no clinical symptom of CHS. In conclusion, staged CAS was feasible in patients with severe carotid artery stenosis and hemodynamic compromise, without inducing severe complication of CHS such as intracranial hemorrhage.

Patient Radiation Exposure During Diagnostic and Therapeutic Procedures for Intracranial Aneurysms: A Multicenter Study.

PURPOSE: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL). MATERIALS AND METHODS: We studied a sample of 490 diagnostic and 371 therapeutic procedures for intracranial aneurysms, which were performed at 23 hospitals in Korea in 2015. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time and total angiographic image frames were obtained and analyzed. RESULTS: Total mean DAP, CAK, fluoroscopy time, and total angiographic image frames were 106.2 ± 66.4 Gy-cm(2), 697.1 ± 473.7 mGy, 9.7 ± 6.5 minutes, 241.5 ± 116.6 frames for diagnostic procedures, 218.8 ± 164.3 Gy-cm(2), 3365.7 ± 2205.8 mGy, 51.5 ± 31.1 minutes, 443.5 ± 270.7 frames for therapeutic procedures, respectively. For diagnostic procedure, the third quartiles for DRLs were 144.2 Gy-cm(2) for DAP, 921.1 mGy for CAK, 12.2 minutes for fluoroscopy times and 286.5 for number of image frames, respectively. For therapeutic procedures, the third quartiles for DRLs were 271.0 Gy-cm(2) for DAP, 4471.3 mGy for CAK, 64.7 minutes for fluoroscopy times and 567.3 for number of image frames, respectively. On average, rotational angiography was used 1.5 ± 0.7 times/session (range, 0-4; n=490) for diagnostic procedures and 1.6 ± 1.2 times/session (range, 0-4; n=368) for therapeutic procedures, respectively. CONCLUSION: Radiation dose as measured by DAP, fluoroscopy time and image frames were lower in our patients compared to another study regarding cerebral angiography, and DAP was lower with fewer angiographic image frames for therapeutic procedures. Proposed DRLs can be used for quality assurance and patient safety in diagnostic and therapeutic procedures.

Spontaneous recanalization of an occluded middle cerebral artery in a patient with moyamoya.

Moyamoya disease is a rare cerebrovascular disorder that is characterized by progressive stenosis of the distal portion of the internal carotid artery and its main branches. Here the authors present the first case of spontaneous recanalization of an occluded middle cerebral artery in a woman with moyamoya who had not undergone surgical or endovascular treatment. Although the exact mechanisms remain unclear, spontaneous recanalization in moyamoya could be considered a possible phenomenon. Thus, the neurosurgeons should always pay attention to the pathological variety of dynamic changes in the cerebrovascular structure in moyamoya.

Can clinical and MRI findings predict the prognosis of variant and classical type of posterior reversible encephalopathy syndrome (PRES)?

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is characterized by clinical symptoms that are associated with bilateral and symmetric vasogenic edema in the parietal and occipital lobes. However, this is rarely present with predominant involvement of the brain stem and cerebellum (variant). PURPOSE: To evaluate which clinical or magnetic resonance imaging (MRI) findings can help to predict the prognosis of variant and classical type of PRES and whether or not there is difference between two types of PRES. MATERIAL AND METHODS: We retrospectively evaluated MRI and clinical findings from 49 patients with PRES. These patients were divided into two groups. In group I, patients had atypical distribution of lesions. In group II, patients had typical distribution of lesions. Follow-up MRI was performed on 26 patients. We assessed the MRI features, clinical data, and the patients' outcomes. RESULTS: The mean blood pressure (BP) was significantly higher in group I (195.52/121.09 mmHg and 156.78/99.53 mmHg for groups I and II, respectively). The other factors assessed were not significantly different between the two groups. Lesions in 24 of 26 patients reversed upon follow-up. Sequelae were observed in 11 patients (group I, 7; group II, 4). However, there were no significant differences between the two groups. Except for those patients who died, seven of the nine patients with sequelae upon follow-up imaging had hemorrhage or irreversibility of lesions. CONCLUSION: Even though BP influences the involvement of the brain stem, involvement of the brain stem is not influential on the prognosis. It seems that the influential factor to prognosis is the reversibility of lesions and hemorrhage.

Serum YKL-40 levels correlate with infarct volume, stroke severity, and functional outcome in acute ischemic stroke patients.

BACKGROUND AND PURPOSE: YKL-40 is associated with various neurological disorders. However, circulatory YKL-40 levels early after onset of acute ischemic stroke (AIS) have not been systematically assessed. We aimed to identify the temporal changes and clinical usefulness of measuring serum YKL-40 immediately following AIS. METHODS: Serum YKL-40 and C-reactive protein (CRP) levels were monitored over time in AIS patients (n = 105) and compared with those of stroke-free controls (n = 34). Infarct volume and stroke severity (National Institutes of Health Stroke Scale; NIHSS) were measured within 48 hours of symptom onset, and functional outcome (modified Rankin Scale; mRS) was measured 3 months after AIS. RESULTS: Within 12 hours of symptom onset, levels of YKL-40 (251 vs. 41 ng/mL) and CRP (1.50 vs. 0.96 µg/mL) were elevated in AIS patients compared to controls. The power of YKL-40 for discriminating AIS patients from controls was superior to that of CRP (area under the curve 0.84 vs. 0.64) and YKL-40 (r = 0.26, P<0.001) but not CRP levels were correlated with mRS. On day 2 of admission (D2), YKL-40 levels correlated with infarct volume and NIHSS. High YKL-40 levels predicted poor functional outcome (odds ratio 5.73, P = 0.03). YKL-40 levels peaked on D2 and declined on D3, whereas CRP levels were highest on D3. CONCLUSIONS: Our results demonstrate serial changes in serum YKL-40 levels immediately following AIS and provide the first evidence that it is a valid indicator of AIS extent and an early predictor of functional outcome.

Uremic encephalopathy with atypical magnetic resonance features on diffusion-weighted images.

Uremic encephalopathy is a well-known disease with typical MR findings including bilateral vasogenic or cytotoxic edema at the cerebral cortex or basal ganglia. Involvement of the basal ganglia has been very rarely reported, typically occurring in uremic-diabetic patients. We recently treated a patient who had non-diabetic uremic encephalopathy with an atypical lesion distribution involving the supratentorial white matter, without cortical or basal ganglia involvement. To the best of our knowledge, this is only the second reported case of non-diabetic uremic encephalopathy with atypical MR findings.

Assessment of cerebral hemodynamics to acetazolamide using brain perfusion SPECT in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary microangiopathy caused by mutations in the Notch3 gene located on chromosome 19, leading to 4 cardinal features with aura, cerebrovascular ischemic events, mood disturbances, and dementia. Acetazolamide (ACZ) has been promoted as a drug to determine cerebral hemodynamics, including cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) in patients with cerebrovascular disease. In CADASIL patients with small-vessel disease, ACZ may be possible to increase CBF. We present that reduced CBF was dramatically improved after administration of ACZ on Tc-99m ECD brain perfusion SPECT in a CADASIL patient.

Isolated spontaneous dissection of the superior mesenteric artery: percutaneous stent placement in two patients.

Isolated spontaneous dissection of the superior mesenteric artery (SMA) is a rare cause of acute mesenteric ischemia. Two patients were successfully treated by percutaneous stent placement within the main trunk of the SMA. Emphasis is placed on the feasibility of nonsurgical management with percutaneous stent placement of isolated spontaneous dissection of the SMA.

MR evaluation of the "arcuate" sign of posterolateral knee instability.

OBJECTIVE: The purpose of this study was to evaluate associated knee injuries using MR imaging in patients with the "arcuate" sign, a term referring to avulsion fracture of the proximal fibula on conventional radiographs. MATERIAL AND METHODS: MR imaging of 18 cases (17 patients, both knees in one patient) with the arcuate sign on conventional radiographs was retrospectively interpreted to evaluate the associated meniscal, ligamentous, and bony injuries. In 12 cases, MR findings were correlated with surgical results. RESULTS: In all cases, avulsed bony fragments from the proximal pole of the fibula were attached to the fibular collateral ligament, the biceps femoris tendon, or both. Tear of the posterolateral capsule was seen in 12 cases (67%). Injury of the cruciate ligaments was noted in 16 cases (89%): injury to both the anterior cruciate ligament and posterior cruciate ligament was seen in nine cases (50%), injury to only the anterior cruciate ligament was seen in four, and injury to the posterior cruciate ligament only was noted in three. Bone bruises or gross fractures were seen in all cases: bone bruises on the anteromedial femoral condyle were noted in nine cases (50%) and were seen on the anteromedial tibial condyle in five cases (28%). Tear of the medial meniscus was seen in five cases (28%) and tear of the lateral meniscus in four cases (22%). Injury to the popliteus was seen in six cases (33%). Joint effusion was associated in all cases. CONCLUSION: MR imaging is useful for evaluation of associated soft-tissue injuries in patients with the arcuate sign on conventional radiographs. Avulsion injury to the proximal fibula is an important indicator of the internal derangement of the knee and for predicting the mechanism of an injury with varus stress. Cruciate ligament tear and bone bruises on the anteromedial condyle of the femur and tibia are common associated findings.