Robbert J. Nijenhuis

Value and Limitations of Contrast-Enhanced MR Angiography in Spinal Arteriovenous Malformations and Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE: The purpose of this work was to study the validity of MR angiography (MRA) for identification of spinal arteriovenous (AV) abnormalities. MATERIALS AND METHODS: Thirty-four consecutive patients with suspicion of spinal vascular abnormalities underwent digital subtraction angiography (DSA) after MRA. The level and side of the suspected spinal dural arteriovenous fistula (SDAVF) and the feeding arteries in spinal arteriovenous malformations (SAVMs) were determined from the MRA and compared with DSA. RESULTS: DSA revealed SDAVF in 20 abnormalities of which 19 were spinal and 1 was tentorial with spinal drainage, as well as SAVM in 11 patients. In 3 patients, MRA and DSA were both normal. For detection of spinal arteriovenous abnormalities, neither false-positive nor false-negative MRA results were obtained. The MRA-derived level of the feeding artery in SDAVF agreed with DSA in 14 of 19 cases. In 5 cases, a mismatch of 1 vertebral level (not side) was noted for the feeding artery. For the tentorial AVF, only the spinal drainage was depicted; the feeding artery was outside the MRA field of view. In intradural SAVM, the main feeding artery was identified by MRA in 10 of 11 patients. MRA could differentiate between glomerular and fistulous SAVM in 4 of 6 cases and between sacral SDAVF and filum terminale SAVM in 2 of 5 cases. CONCLUSIONS: MRA reliably detects or excludes various types of spinal AV abnormalities and localizes the (predominant) arterial feeder of most spinal AV shunts. Although classification of the subtype of SAVMs remains difficult, with MRA it greatly helps to focus subsequent DSA.

Safety and effectiveness of uterine artery embolization in patients with pedunculated fibroids.

PURPOSE To assess complications and outcomes of uterine artery embolization (UAE) in women with pedunculated fibroids in a large single-center patient cohort. MATERIALS AND METHODS From a database with prospectively collected data from 716 women treated with UAE between 1996 and 2008, 29 women were identified with 31 pedunculated fibroids. Magnetic resonance images obtained before and 3 months after UAE were used to calculate stalk diameter change and volume reduction of both the pedunculated fibroid and uterus. Two observers assessed the overall percentage infarction and infarction of pedunculated fibroid. Complications were recorded and long-term clinical follow-up (mean, 33 months; range, 10-78 months) assessed with use of a questionnaire. RESULTS The mean reduction in uterine and pedunculated fibroid volume was 37% and 33%, respectively. The mean reduction in stalk diameter was 0.3 cm (95% confidence interval [CI]: 0.18, 0.52 cm) or 13% from initial mean diameter. Stalk enhancement was not affected by UAE. The mean pedunculated fibroid infarction and mean overall infarction rates were 87% and 92%, respectively, for observer 1 and 88% and 92% for observer 2, with good interobserver variability. All women returned the questionnaire and no early or late complications of UAE were reported (0%; 95% CI: 0.0%-13.9%). CONCLUSIONS In this small series of pedunculated subserosal fibroids treated with UAE, no complications occurred. The findings suggest that the use of UAE to treat pedunculated subserosal fibroids may be safe and effective.

International consensus on use of focused ultrasound for painful bone metastases: Current status and future directions

Abstract Focused ultrasound surgery (FUS), in particular magnetic resonance guided FUS (MRgFUS), is an emerging non-invasive thermal treatment modality in oncology that has recently proven to be effective for the palliation of metastatic bone pain. A consensus panel of internationally recognised experts in focused ultrasound critically reviewed all available data and developed consensus statements to increase awareness, accelerate the development, acceptance and adoption of FUS as a treatment for painful bone metastases and provide guidance towards broader application in oncology. In this review, evidence-based consensus statements are provided for (1) current treatment goals, (2) current indications, (3) technical considerations, (4) future directions including research priorities, and (5) economic and logistical considerations.

Quality of MR thermometry during palliative MR-guided high-intensity focused ultrasound (MR-HIFU) treatment of bone metastases

BackgroundMagnetic resonance (MR)-guided high-intensity focused ultrasound has emerged as a clinical option for palliative treatment of painful bone metastases, with MR thermometry (MRT) used for treatment monitoring. In this study, the general image quality of the MRT was assessed in terms of signal-to-noise ratio (SNR) and apparent temperature variation. Also, MRT artifacts were scored for their occurrence and hampering of the treatment monitoring.MethodsAnalyses were performed on 224 MRT datasets retrieved from 13 treatments. The SNR was measured per voxel over time in magnitude images, in the target lesion and surrounding muscle, and was averaged per treatment. The standard deviation over time of the measured temperature per voxel in MRT images, in the muscle outside the heated region, was defined as the apparent temperature variation and was averaged per treatment. The scored MRT artifacts originated from the following sources: respiratory and non-respiratory time-varying field inhomogeneities, arterial ghosting, and patient motion by muscle contraction and by gross body movement. Distinction was made between lesion type, location, and procedural sedation and analgesic (PSA).ResultsThe average SNR was highest in and around osteolytic lesions (21 in lesions, 27 in surrounding muscle, n = 4) and lowest in the upper body (9 in lesions, 16 in surrounding muscle, n = 4). The average apparent temperature variation was lowest in osteolytic lesions (1.2°C, n = 4) and the highest in the upper body (1.7°C, n = 4). Respiratory time-varying field inhomogeneity MRT artifacts occurred in 85% of the datasets and hampered treatment monitoring in 81%. Non-respiratory time-varying field inhomogeneities and arterial ghosting MRT artifacts were most frequent (94% and 95%) but occurred only locally. Patient motion artifacts were highly variable and occurred less in treatments of osteolytic lesions and using propofol and esketamine as PSA.ConclusionsIn this study, the general image quality of MRT was observed to be higher in osteolytic lesions and lower in the upper body. Respiratory time-varying field inhomogeneity was the most prominent MRT artifact. Patient motion occurrence varied between treatments and seemed to be related to lesion type and type of PSA. Clinicians should be aware of these observed characteristics when interpreting MRT images.

Embolization of Uterine Leiomyomas with Polyzene F–coated Hydrogel Microspheres: Initial Experience

PURPOSE To evaluate effectiveness and safety of Polyzene F-coated hydrogel microspheres for uterine artery embolization (UAE) in women with symptomatic uterine leiomyomas. MATERIALS AND METHODS Between August 2006 and August 2008, 86 nonconsecutive premenopausal women (mean age, 43.9 years; median, 44 y; range, 28-54 y) were treated with UAE. Calibrated microspheres of 500, 700, and 900 μm, alone or in combination, were used as embolic agents. Change in uterine and tumor volume and tumor infarction rate during follow-up were assessed with magnetic resonance imaging. Clinical follow-up was evaluated by the Uterine Fibroid Severity and Quality Of Life (UFS-QOL) questionnaire at baseline, 3 months, and last follow-up in November 2008. RESULTS At 3 months, mean volume reductions of the dominant leiomyoma and uterus were 45% and 42%, respectively, and complete infarction of the dominant leiomyoma was achieved in 69 patients (80%). Complete infarction of the overall tumor burden was achieved in 52 patients (60%). Infarction rates of the dominant tumor and overall tumor burden were more than 90% in 81 patients (94%) and 79 patients (91%), respectively. During follow-up, permanent amenorrhea developed in seven women (8.1%). Four women (4.7%) had additional therapy after UAE; three had a hysterectomy and one had a second embolization. The UFS-QOL showed significant improvement in symptom severity and quality of life after 3 months that continued to improve at last follow-up (mean, 12.8 months). CONCLUSIONS In this preliminary study, Polyzene F-coated hydrogel microspheres for UAE resulted in good dominant and overall tumor infarction in most patients, with corresponding improvement of symptoms. Determining optimal sizing of the material and comparing outcomes versus those of other embolic agents requires additional study.

Spinal Dural Fistulas without Swelling and Edema of the Cord as Incidental Findings

This short report describes 5 patients with incidentally found spinal dural AVFs without cord edema. All patients were adults and were being imaged for nonspecific back pain. Four AVFs were conal and one was cervical. Generally, at the time of diagnosis, patients with spinal AVFs have long-standing symptoms and cord edema and the classic imaging triad of cord edema, dilated perimedullary veins, and, at times, contrast cord enhancement makes the diagnosis easy. This nicely illustrated report seems to indicate that symptoms in spinal AVFs correlate with the presence of edema, a finding not present when these are incidentally found. SUMMARY: SDAVFs cause hypertension and hence outflow obstruction in the perimedullary venous system resulting in swelling and edema of the cord followed by dysfunction. Clinical presentation is usually with gradual progressive paraparesis, numbness, and sphincter problems. MR imaging typically demonstrates the dilated perimedullary veins and the swelling and edema of the cord. During the past few years, we incidentally found an SDAVF on MR imaging with dilated perimedullary veins but without swelling and edema of the cord in 5 patients with unrelated presenting clinical symptoms. Spinal angiography confirmed the presence of an SDAVF in all 5 patients. Although the indication was considered questionable, eventually all 5 fistulas were endovascularly or surgically treated, resulting in normalization of the MR images.

Iatrogenic lumbar pseudoaneurysm causing dural sac compression after spine surgery

A 69-year-old man presented 3 months after lumbar spine surgery with progressive paraparesis and bladder and sphincter dysfunction caused by a lumbar artery pseudoaneurysm compressing the dural sac. After embolization with glue, the thrombosed pseudoaneurysm substantially decreased in size and the patients neurological symptoms improved.

Is an Intrauterine Device a Contraindication for Uterine Artery Embolization? A Study of 20 Patients

The presence of an intrauterine device (IUD) has been traditionally considered a risk factor for postprocedural infection in patients undergoing uterine artery embolization (UAE). The authors retrospectively evaluated the occurrence of infectious complications following embolization in 20 women with IUDs. After a mean follow-up of 20.5 months, none of the patients developed an infectious complication. One patient required hysterectomy following embolization for persistent pain. Pathologic evaluation of the hysterectomy specimen demonstrated ischemia without evidence of inflammation. This experience suggests that the presence of an IUD might not be considered a contraindication for UAE.

Volumetric MR-guided high-intensity focused ultrasound with direct skin cooling for the treatment of symptomatic uterine fibroids: proof of concept study

Objective. To prospectively assess the safety and technical feasibility of volumetric magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation with direct skin cooling (DISC) during treatment of uterine fibroids. Methods. In this proof-of-concept study, eight patients were consecutively selected for clinical MR-HIFU ablation of uterine fibroids with the use of an additional DISC device to maintain a constant temperature () at the interface between the HIFU table top and the skin. Technical feasibility was verified by successful completion of MR-HIFU ablation. Contrast-enhanced T1-weighted MRI was used to measure the treatment effect (nonperfused volume (NPV) ratio). Safety was evaluated by recording of adverse events (AEs) within 30 days’ follow-up. Results. All MR-HIFU treatments were successfully completed in an outpatient setting. The median NPV ratio was 0.56 (IQR [0.27–0.72]). Immediately after treatment, two patients experienced coldness related discomfort which resolved at the same day. No serious (device-related) AEs were reported. Specifically, no skin burns, cold injuries, or subcutaneous edema were observed. Conclusion. This study showed that it is safe and technically feasible to complete a volumetric MR-HIFU ablation with DISC. This technique may reduce the risk of thermal injury to the abdominal wall during MR-HIFU ablation of uterine fibroids. This trial is registered with NTR4189.

Mapping the Vasculature of the Spinal Cord

Spinal cord arteries and veins represent tiny, millimeter-to-submillimeter blood vessels for which in vivo depiction has only recently become possible using noninvasive imaging techniques. A brief overview of the complex and clinically relevant vascular anatomy of the spinal cord is provided, including the supplying and draining trajectories. A magnetic resonance angiography protocol is outlined that enables the visualization and differentiation of the spinal cord arteries and veins. Finally, it is discussed how the complex and tortuous venous anatomy may confound the interpretation of blood oxygen level–dependent (BOLD) activation responses obtained from the spinal cord.