Direct Aspiration versus Combined Technique for Distal Medium-Vessel Occlusions: Comparison on a Human Placenta Model

BACKGROUND AND PURPOSE

Mechanical thrombectomy appears to be a promising option for distal medium-vessel occlusions, for which intravenous thrombolysis is effective but may be insufficient when used alone. This study aimed to determine the optimal technique for these distal mechanical thrombectomies using the human placenta model.

MATERIALS AND METHODS

Twenty-four procedures were performed, allowing comparison of direct aspiration (n = 12) versus the combined technique (n = 12). Two positions of the aspiration catheter were tested for each of these techniques: in direct contact with the clot and at a distance from it (5-10 mm). Two types of clots were tested: red blood cell-rich clots and fibrin-rich clots. First-pass recanalization and induced arterial collapse and traction were assessed.

RESULTS

The first-pass recanalization was less frequent for direct aspiration than for the combined technique, without reaching statistical significance (41.7% versus 75.0%, P = .098). Full collapse (P < .001) and extended arterial traction (P = .001) were significantly less frequent for direct aspiration. For direct aspiration with the aspiration catheter not in direct contact with the clot, there was not a single first-pass recanalization and there was systematic arterial collapse, resulting in a no-flow in the aspiration syringe.

CONCLUSIONS

The combined technique appears to be more harmful, and although direct aspiration has a lower rate of first-pass recanalization, it seems appropriate to try direct aspiration as a first-line procedure. However, if the aspiration catheter cannot reach the clot, it is not useful or even risky to try aspiration alone. These results need to be confirmed by clinical studies.

Follow-up of Intracranial Aneurysms Treated by Flow Diverters: Evaluation of Parent Artery Patency Using 3D-T1 Gradient Recalled-Echo Imaging with 2-Point Dixon in Combination with 3D-TOF-MRA with Compressed Sensing

BACKGROUND AND PURPOSE

MRA assessment of parent artery patency after flow-diverter placement is complicated by imaging artifacts produced by these devices. The purpose of this study was to assess the accuracy of liver acquisition with volume acceleration-flex technique (LAVA-Flex) MRA in combination with 3D-TOF with HyperSense MRA for the evaluation of parent vessel status after intracranial flow-diverter placement.

MATERIALS AND METHODS

Fifty-six patients treated by flow diversion and followed with both DSA and 3T MRA between November 2020 and August 2021 were included. All patients were evaluated for parent artery patency using the same imaging protocol (DSA, noncontrast MRA including 3D-TOF with HyperSense and LAVA-Flex, and contrast-enhanced MRA, including time-resolved imaging of contrast kinetics MRA and delayed contrast-enhanced MRA).

RESULTS

With DSA as a criterion standard to evaluate the patency of the parent vessel, noncontrast MRA had a good specificity (0.83) and positive predictive value (0.65), better than contrast-enhanced MRA (0.55 and 0.41, respectively). Both had excellent sensitivity and negative predictive value: noncontrast MRA, 0.93 and 0.97, respectively; contrast-enhanced MRA, 0.93 and 0.96, respectively. Specificity and positive predictive value tended to be lower for patients treated with additional devices than for those treated with flow diverters exclusively and for patients treated with a specific type of flow diverter.

CONCLUSIONS

Noncontrast MRA can be used for noninvasive follow-up of intracranial aneurysms treated by flow diverters. The combined use of LAVA-Flex and 3D-TOF with HyperSense sequences allows monitoring the status of the parent artery and aneurysm occlusion.

Advanced multiparametric magnetic resonance imaging of multinodular and vacuolating neuronal tumor

BACKGROUND AND PURPOSE

Multinodular and vacuolating neuronal tumor (MVNT) of the cerebrum is a rare brain lesion with suggestive imaging features. The aim of our study was to report the largest series of MVNTs so far and to evaluate the utility of advanced multiparametric magnetic resonance (MR) techniques.

METHODS

This multicenter retrospective study was approved by our institutional research ethics board. From July 2014 to May 2019, two radiologists read in consensus the MR examinations of patients presenting with a lesion suggestive of an MVNT. They analyzed the lesions' MR characteristics on structural images and advanced multiparametric MR imaging.

RESULTS

A total of 64 patients (29 women and 35 men, mean age 44.2 ± 15.1 years) from 25 centers were included. Lesions were all hyperintense on fluid-attenuated inversion recovery and T2-weighted imaging without post-contrast enhancement. The median relative apparent diffusion coefficient on diffusion-weighted imaging was 1.13 [interquartile range (IQR), 0.2]. Perfusion-weighted imaging showed no increase in perfusion, with a relative cerebral blood volume of 1.02 (IQR, 0.05) and a relative cerebral blood flow of 1.01 (IQR, 0.08). MR spectroscopy showed no abnormal peaks. Median follow-up was 2 (IQR, 1.2) years, without any changes in size.

CONCLUSIONS

A comprehensive characterization protocol including advanced multiparametric magnetic resonance imaging sequences showed no imaging patterns suggestive of malignancy in MVNTs. It might be useful to better characterize MVNTs.

Multinodular and Vacuolating Posterior Fossa Lesions of Unknown Significance

Multinodular and vacuolating neuronal tumor of the cerebrum is a rare supratentorial brain tumor described for the first time in 2013. Here, we report 11 cases of infratentorial lesions showing similar striking imaging features consisting of a cluster of low T1-weighted imaging and high T2-FLAIR signal intensity nodules, which we referred to as multinodular and vacuolating posterior fossa lesions of unknown significance. No relationship was found between the location of the lesion and clinical symptoms. A T2-FLAIR hypointense central dot sign was present in images of 9/11 (82%) patients. Cortical involvement was present in 2/11 (18%) of patients. Only 1 nodule of 1 multinodular and vacuolating posterior fossa lesion of unknown significance showed enhancement on postcontrast T1WI. DWI, SWI, MRS, and PWI showed no malignant pattern. Lesions did not change in size or signal during a median follow-up of 3 years, suggesting that multinodular and vacuolating posterior fossa lesions of unknown significance are benign malformative lesions that do not require surgical intervention or removal.

Imaging of giant cerebral aneurysms

The aim of this study was to review the different imaging techniques for analysing giant intracranial aneurysms (digital subtraction angiography [DSA], magnetic resonance imaging [MRI], computed tomography [CT]) imaging and explain their respective contribution to the understanding of the characteristics of these complex aneurysms. Giant aneurysms have a complex pathology with multiple stages of evolution and consequences. Therefore, complex imaging is mandatory to enhance the understanding of these parameters and to plan an often complicated treatment strategy. DSA remains the gold standard for analysing aneurysms, but non-invasive sectional imaging (CT, MRI) also provides essential information in the specific case of giant aneurysms.

[Post-traumatic syringomyelia: What should know the urologist?]

The incidence of post-traumatic syringomyelia (PTS) is estimated according to recent studies at 25 to 30% of patients with traumatic spinal cord injuries in magnetic resonance imaging (MRI), which remains the gold standard exam for syringomyelia diagnosis and monitoring. Syringomyelia is translated by an increased cord signal (similar to CSF) with low-density T1-weighted image and high-density T2-weighted image, which extends beyond site of initial lesion at least to two vertebral segments. Two conditions are required for development of PTS: traumatic spinal cord injury and blocked the flow of CSF epidural. The mean interval from spinal cord injury to diagnosis SPT was 2.8years (range, 3months to 34years). The commonest symptoms are pain and sensory loss. PTS should be suspected if the patient has new neurological symptoms above level of injury, such as dissociated sensory injuries, reflexes abolition, and motor deficit, after the neural function becomes stable for certain time. In urologic practice, new neurological symptoms could be bladder and/or erectile dysfunction. The medical management based on prevention efforts with closed-glottis pushing, which could aggravate the syrinx cavity. In urology, extracorporeal shockwave lithotripsy, and laparoscopic or robotic surgery could extend the syrinx cavity for the same reason (increase abdominal pressure). The indications for surgical intervention and optimal surgical treatment technique for patients with PTS are not consensual. The literature demonstrated that surgery PTS is effective at arresting or improving motor deterioration, but not sensory dysfunction or pain syndromes.

Intravenous immunoglobulin-associated cranial pachymeningitis

To date, intravenous immunoglobulin (IvIg) has more often been considered as a safe medication. However, with the wider use of IvIg, severe side effects have also been reported to occur in IvIg-treated patients, notably aseptic meningitis. Other neurological complications have more rarely been described in patients receiving IvIg therapy, e.g. stroke or acute encephalopathy. We recently observed a case which is of particular interest, as the patient with steroid-refractory polyarteritis nodosa developed cranial pachymeningitis related to IvIg therapy. To our knowledge, this is the first reported case of cranial pachymeningitis complicating IvIg therapy. Our findings emphasize the importance of recognizing IvIg-related neurological complications in IvIg-treated patients. As cranial pachymeningitis is a fibrosing process, both recognition and management at an early stage are required to prevent definite neurological impairment in patients.

Disorganized somatotopy in the putamen of patients with focal hand dystonia

OBJECTIVE

To explore the selectivity of neuronal somatotopic representation in the striatum of patients with unilateral task-specific dystonia of the right arm.

MATERIALS AND METHODS

The authors used fMRI in 14 right-handed dystonic subjects to examine putaminal organization. Subjects performed flexion/extension of the right and left fingers and toes, and contraction of the lips.

RESULTS

Compared to healthy volunteer subjects, dystonic subjects had altered somatotopic organization in the left putamen, contralateral to the affected hand. Disease severity correlated with underactivation and decreased distance between right hand and lip representations. In the right putamen, ipsilateral to the affected hand, the somatotopic organization was not altered but disease severity also correlated with reduced distances between limbs.

CONCLUSION

In dystonia there may be a dedifferentiation of the normally segregated cortico-subcortical sensorimotor maps in the putamen, which may contribute to the loss of functional selectivity of muscle activity observed in these dystonic subjects.

Diagnosis of spinal dural arteriovenous fistula with multidetector row computed tomography: a case report

Spinal dural arteriovenous fistulas are a rare cause of myelopathy. Nonspecific symptoms may delay the diagnosis. Magnetic resonance imaging and spinal angiography are routinely used to establish the diagnosis. In our case abnormalities on magnetic resonance imaging only suggested spinal dural arteriovenous fistulas. Multidetector row computed tomography (MRCT) led to the diagnosis which was confirmed by angiography.

Partially overlapping neural networks for real and imagined hand movements

Neuroimagery findings have shown similar cerebral networks associated with imagination and execution of a movement. On the other hand, neuropsychological studies of parietal-lesioned patients suggest that these networks may be at least partly distinct. In the present study, normal subjects were asked to either imagine or execute auditory-cued hand movements. Compared with rest, imagination and execution showed overlapping networks, including bilateral premotor and parietal areas, basal ganglia and cerebellum. However, direct comparison between the two experimental conditions showed that specific cortico-subcortical areas were more engaged in mental simulation, including bilateral premotor, prefrontal, supplementary motor and left posterior parietal areas, and the caudate nuclei. These results suggest that a specific neuronal substrate is involved in the processing of hand motor representations.