Double lesion MRgFUS thalamotomy for essential tremor: 4.5-year outcomes and framework for assessing loss of efficacy and tremor progression.

BACKGROUND: The essential tremor (ET) course to 54 months post-unilateral VIM/PSA magnetic resonance-guided focused ultrasound (MRgFUS) in the treated arm (TA) and non-treated arm (NTA) of 12 patients is reported. METHODS: Tremor severity was rated using Bain Findley spirography (BFS) scores in the TA and NTA. We divided follow-up into 'Early' (0-6 months) and 'Late' (6-54 months) phases, to minimise the effect of peri-lesion oedema resolution on the latter. RESULTS: The mean baseline BFS score was 6.2 in TA and 5.7 in the NTA. After unilateral VIM/PSA MRgFUS, mean BFS improved in TA at all subsequent time points (p < 0.001), with no significant differences between BFS scores at consecutive assessments or between 1 and 54 months, while the NTA BFS scores worsened between 12 and 24 months (p < 0.003). Three patients showed worsening of their TA BFS scores and an increasing NTA-TA BFS difference, indicating slower tremor worsening in TA compared to NTA, whilst one patient showed a greater rate of worsening in the TA compared to NTA BFS. CONCLUSION: After 54 months, the beneficial effect of MRgFUS is usually maintained with any worsening of BFS scores in TA slower than in NTA. Loss of treatment benefit is rare.

Tremor assessment scales before, during and after MRgFUS for essential tremor - results, recommendations and implications.

BACKGROUND: neurosurgical interventions such as MR-guided focused ultrasound (MRgFUS) are increasingly deployed for treatment of essential tremor. OBJECTIVE: to make recommendations for monitoring treatment effects during and after MRgFUS based on our investigation of correlations between different scales of tremor severity. METHODS: twenty-five clinical assessments were collected from thirteen patients before and after unilateral MRgFUS sequential lesioning of the thalamus and posterior subthalamic area for alleviating essential tremor. Scales included Bain Findley Spirography (BFS), Clinical Rating Scale for Tremor (CRST), Upper Extremity Total Tremor Score (UETTS) and Quality of Life of Essential Tremor (QUEST), and were documented at baseline, while lying in the scanner with stereotactic frame attached (BFS), and at 24-month follow-up. RESULTS: the four different scales of tremor severity all correlated significantly. BFS and CRST showed a strong correlation of 0.833 (p < 0.001). BFS, UETTS and CRST correlated moderately with QUEST (ρ = 0.575-0.721, p < 0.001). BFS and UETTS correlated significantly with all CRST subparts, with the strongest correlation between UETTS and CRST part C (ρ = 0.831, p < 0.001). Moreover, BFS drawn sitting upright in an outpatient setting correlated with spirals drawn in a supine position on the scanner bed with the stereotactic frame attached. CONCLUSION: we recommend a combination of BFS & UETTS for intraoperative assessment of awake essential tremor patients and BFS & QUEST for pre-operative and follow-up assessments, as these scale sets are quick and simple to collect and provide meaningful information whilst meeting the practical constraints of intraoperative assessment.

Guidelines for the safe provision of anaesthesia in magnetic resonance units 2019: Guidelines from the Association of Anaesthetists and the Neuro Anaesthesia and Critical Care Society of Great Britain and Ireland.

There has been an increase in the number of units providing anaesthesia for magnetic resonance imaging and the strength of magnetic resonance scanners, as well as the number of interventions and operations performed within the magnetic resonance environment. More devices and implants are now magnetic resonance imaging conditional, allowing scans to be undertaken in patients for whom this was previously not possible. There has also been a revision in terminology relating to magnetic resonance safety of devices. These guidelines have been put together by organisations who are involved in the pathways for patients needing magnetic resonance imaging. They reinforce the safety aspects of providing anaesthesia in the magnetic resonance environment, from the multidisciplinary decision making process, the seniority of anaesthetist accompanying the patient, to training in the recognition of hazards of anaesthesia in the magnetic resonance environment. For many anaesthetists this is an unfamiliar site to give anaesthesia, often in a remote site. Hospitals should develop and audit governance procedures to ensure that anaesthetists of all grades are competent to deliver anaesthesia safely in this area.

Postanastomotic transplant renal artery stenosis: association with de novo class II donor-specific antibodies.

In this study, we analyze the outcomes of transplant renal artery stenosis (TRAS), determine the different anatomical positions of TRAS, and establish cardiovascular and immunological risk factors associated with its development. One hundred thirty-seven of 999 (13.7%) patients had TRAS diagnosed by angiography; 119/137 (86.9%) were treated with angioplasty, of which 113/137 (82.5%) were stented. Allograft survival in the TRAS+ intervention, TRAS+ nonintervention and TRAS- groups was 80.4%, 71.3% and 83.1%, respectively. There was no difference in allograft survival between the TRAS+ intervention and TRAS- groups, p = 0.12; there was a difference in allograft survival between the TRAS- and TRAS+ nonintervention groups, p < 0.001, and between the TRAS+ intervention and TRAS+ nonintervention groups, p = 0.037. TRAS developed at the anastomosis, within a bend/kink or distally. Anastomotic TRAS developed in living donor recipients; postanastomotic TRAS (TRAS-P) developed in diabetic and older patients who received grafts from deceased, older donors. Compared with the TRAS- group, patients with TRAS-P were more likely to have had rejection with arteritis, odds ratio (OR): 4.83 (1.47-15.87), p = 0.0095, and capillaritis, OR: 3.03 (1.10-8.36), p = 0.033. Patients with TRAS-P were more likely to have developed de novo class II DSA compared with TRAS- patients hazard ratio: 4.41 (2.0-9.73), p < 0.001. TRAS is a heterogeneous condition with TRAS-P having both alloimmune and traditional cardiovascular risk factors.

Conservative management of diabetic forefoot ulceration complicated by underlying osteomyelitis: the benefits of magnetic resonance imaging.

AIMS: To assess efficacy of conservative management of neuropathic forefoot ulcers with underlying osteomyelitis in subjects with diabetes when magnetic resonance imaging (MRI) is used to confirm or establish diagnosis and to guide antibiotic duration. METHODS: A retrospective cohort study over 6 years assessing rates of ulcer healing, relapse and amputation. Antibiotics were continued for 3-month cycles with interval MRI: if the lesion had healed and bone signal change resolved or improved, antibiotics were discontinued; if the lesion had not healed or there was no difference in bone signal change, antibiotics were continued for a further 3-month cycle; clinical or radiological deterioration resulted in endoluminal or open vascular surgical intervention where appropriate, or digital or more proximal amputation. RESULTS: There were 53 episodes in 47 subjects (mean +/- sd age 62 +/- 13 years, duration of diabetes 19 +/- 13 years, glycated haemoglobin 8.4 +/- 1.6%; six with Type 1 diabetes and seven with end-stage renal failure). Successful healing without relapse was achieved in 40 episodes (75%) [median (range) duration of antibiotics 6 (3-12) months and follow-up post-cessation of antibiotics 15 (3-58) months]. Relapse occurred in six episodes (13%) at 31 (2-38) months post-cessation of antibiotics. There were one major (2%) and eight minor (15%) amputations. Five subjects have died (11%), all without foot ulcers. CONCLUSIONS: High rates of healing and low rates of amputation were achieved. The use of MRI was associated with long courses of antibiotics, but particularly low relapse rate.

Cost-effectiveness of magnetic resonance-guided focused ultrasound surgery for treatment of uterine fibroids.

OBJECTIVE: To estimate the cost-effectiveness of a treatment strategy for symptomatic uterine fibroids, which starts with Magnetic Resonance-guided Focused Ultrasound Surgery (MRgFUS) as compared with current practice comprising uterine artery embolisation, myomectomy and hysterectomy. DESIGN: Cost-utility analysis based on a Markov model. SETTING: National Health Service (NHS) Trusts in England and Wales. POPULATION: Women for whom surgical treatment for uterine fibroids is being considered. METHODS: The parameters of the Markov model of the treatment of uterine fibroids are drawn from a series of clinical studies of MRgFUS, and from the clinical effectiveness literature. Health-related quality of life is measured using the 6D. Costs are estimated from the perspective of the NHS. The impact of uncertainty is examined using deterministic and probabilistic sensitivity analysis. MAIN OUTCOME MEASURES: Incremental cost-effectiveness measured by cost per quality-adjusted life-year (QALY) gained. RESULTS: The base-case results imply a cost saving and a small QALY gain per woman as a result of an MRgFUS treatment strategy. The cost per QALY gained is sensitive to cost of MRgFUS relative to other treatments, the age of the woman and the nonperfused volume relative to the total fibroids volume. CONCLUSIONS: A treatment strategy for symptomatic uterine fibroids starting with MRgFUS is likely to be cost-effective.

The Effect of Arterial Curvature on Blood Flow in Arterio-Venous Fistulae: Realistic Geometries and Pulsatile Flow.

Arterio-Venous Fistulae (AVF) are regarded as the "gold standard" method of vascular access for patients with End-Stage Renal Disease (ESRD) who require haemodialysis. However, up to 60% of AVF do not mature, and hence fail, as a result of Intimal Hyperplasia (IH). Unphysiological flow and oxygen transport patterns, associated with the unnatural and often complex geometries of AVF, are believed to be implicated in the development of IH. Previous studies have investigated the effect of arterial curvature on blood flow in AVF using idealized planar AVF configurations and non-pulsatile inflow conditions. The present study takes an important step forwards by extending this work to more realistic non-planar brachiocephalic AVF configurations with pulsatile inflow conditions. Results show that forming an AVF by connecting a vein onto the outer curvature of an arterial bend does not, necessarily, suppress unsteady flow in the artery. This finding is converse to results from a previous more idealized study. However, results also show that forming an AVF by connecting a vein onto the inner curvature of an arterial bend can suppress exposure to regions of low wall shear stress and hypoxia in the artery. This finding is in agreement with results from a previous more idealized study. Finally, results show that forming an AVF by connecting a vein onto the inner curvature of an arterial bend can significantly reduce exposure to high WSS in the vein. The results are important, as they demonstrate that in realistic scenarios arterial curvature can be leveraged to reduce exposure to excessively low/high levels of WSS and regions of hypoxia in AVF. This may in turn reduce rates of IH and hence AVF failure.

Gonadotrophin-releasing hormone and magnetic-resonance-guided ultrasound surgery for uterine leiomyomata.

OBJECTIVE: Magnetic-resonance-guided focused ultrasound is a novel, noninvasive technique of thermoablation for uterine leiomyomata. The hypothesis of this study was that pretreatment of leiomyomata with gonadotrophin-releasing hormone (GnRH) agonists would allow effective treatment of larger uterine leiomyomata, increasing the number of women who could benefit from this technique. METHODS: We report a prospective study of women with leiomyomata in excess of 10 cm in diameter who received GnRH agonist before magnetic-resonance-guided focused ultrasound treatment. Eligible participants were recruited from the gynecology outpatient clinics. Entry criteria were a minimal leiomyoma symptom severity score and confirmation of uterine dimensions based on screening magnetic resonance imaging. These women received a 3-month course of GnRH agonists followed by magnetic-resonance-guided focused ultrasound treatment. The primary outcome measurement was reported change in symptom severity score as judged by the Uterine Fibroid Symptom and Quality of Life questionnaire. Comparison was made at enrollment, treatment, and at 3, 6, and 12 months posttreatment. A secondary outcome was the measured change in target leiomyoma volume. RESULTS: Forty-nine women were enrolled in the study. There was a 45% reduction in median symptom severity score at 6 months and 48% at 12 months posttreatment, with 83% of women achieving at least a 10-point reduction in symptom scoring at 6 months and 89% at 12 months (P < .001). There was an average reduction in target leiomyoma volume of 21% overall at 6 months (P < .001) and 37% at 12 months (P < .001). No serious infective complications or emergency operative interventions were recorded. CONCLUSION: The use of GnRH agonist therapy before magnetic-resonance-guided focused ultrasound improves the thermoablative treatment effect. LEVEL OF EVIDENCE: II-3.

Curvature and tortuosity of the superficial femoral artery: a possible risk factor for peripheral arterial disease.

Atherosclerosis in the superficial femoral artery (SFA) resulting in peripheral arterial disease is more common in men than women and shows a predilection for the region of the adductor canal. Blood flow patterns are related to development of atherosclerosis, and we investigated if curvature and tortuosity of the femoral artery differed between young men and women and if differences resulted in adverse flow patterns. Magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) were combined in 18 young adult volunteers (9 men) to assess the relationship of flow features to likely sites of future atherosclerosis formation. Subjects underwent MRI of the right SFA, three-dimensional vascular geometry was reconstructed, and measures of tortuosity and curvature were calculated. Tortuosity and curvature were significantly greater for men than women, and this was related to increased body surface area, body mass index, or weight in men. In both sexes, "tortuosity" increased from the midthigh to the popliteal fossa. The greatest curvature was found within the distal quarter of the SFA. CFD modeling was undertaken on MRI-based reconstructions of the SFA. Wall shear stresses (WSS) were extracted from the computations. WSS showed greater spatial variation in the men than in the women, and the men exhibited lower mean WSS. These data indicate that sex differences related to body size and anatomical course of the femoral artery may contribute to the enhanced risk of focal atherosclerosis in the adductor canal.

Magnetic resonance guided focused ultrasound surgery of uterine fibroids--the tissue effects of GnRH agonist pre-treatment.

OBJECTIVE: The purpose of this study was to determine the ablative effect of magnetic resonance guided focused ultrasound (MRgFUS) on fibroid tissue following the administration of gonadotrophin releasing hormone (GnRH) agonist. STUDY DESIGN: Fifty women with clinically symptomatic uterine fibroids were treated. Those with uterine diameter of 10 cm or greater were given 3 months pre-treatment with GnRH agonists. Data regarding number of ultrasound sonications, Joules of energy delivered and volume of thermal destruction was recorded. RESULTS: Twenty-seven subjects were given GnRH agonist therapy before MRgFUS and 23 women underwent MRgFUS without pre-treatment. All patients in both study groups completed MR guided FUS as an outpatient procedure with no device related adverse events reported. In the group of women who received GnRH agonists, the volume of ablation was significantly larger than that in the control group (0.06 cm3 versus 0.03 cm3, P<0.05), per Joule of energy applied. CONCLUSION: The use of GnRH agonists potentiates the thermal effects of MRgFUS in women undergoing treatment of uterine fibroids.

Tibio-femoral movement in the living knee. A study of weight bearing and non-weight bearing knee kinematics using 'interventional' MRI.

The aim of this study was to image tibio-femoral movement during flexion in the living knee. Ten loaded male Caucasian knees were initially studied using MRI, and the relative tibio-femoral motions, through the full flexion arc in neutral tibial rotation, were measured. On knee flexion from hyperextension to 120 degrees , the lateral femoral condyle moved posteriorly 22 mm. From 120 degrees to full squatting there was another 10 mm of posterior translation, with the lateral femoral condyle appearing almost to sublux posteriorly. The medial femoral condyle demonstrated minimal posterior translation until 120 degrees . Thereafter, it moved 9 mm posteriorly to lie on the superior surface of the medial meniscal posterior horn. Thus, during flexion of the knee to 120 degrees , the femur rotated externally through an angle of 20 degrees . However, on flexion beyond 120 degrees , both femoral condyles moved posteriorly to a similar degree. The second part of this study investigated the effect of gender, side, load and longitudinal rotation. The pattern of relative tibio-femoral movement during knee flexion appears to be independent of gender and side. Femoral external rotation (or tibial internal rotation) occurs with knee flexion under loaded and unloaded conditions, but the magnitude of rotation is greater and occurs earlier on weight bearing. With flexion plus tibial internal rotation, the pattern of movement follows that in neutral. With flexion in tibial external rotation, the lateral femoral condyle adopts a more anterior position relative to the tibia and, particularly in the non-weight bearing knee, much of the femoral external rotation that occurs with flexion is reversed.

Prevalence of renal artery stenosis in subjects with type 2 diabetes and coexistent hypertension.

OBJECTIVE: To assess the prevalence of renal artery stenosis (RAS) in subjects with type 2 diabetes and coexistent hypertension by using magnetic resonance angiography (MRA) of the renal arteries, to assess clinical and biochemical predictors of RAS, and to assess the hemodynamic significance of RAS, by using the captopril test (a measure of the response of plasma renin activity to a single oral dose of captopril). RESEARCH DESIGN AND METHODS: A total of 117 subjects with type 2 diabetes and coexistent hypertension between 40 and 70 years of age and with creatinine concentrations < 150 micromol/l were recruited from two inner-city general diabetes clinics. All subjects underwent MRA of the renal arteries. In a subgroup of 85 subjects, data concerning possible clinical and biochemical predictors of RAS were collected, and the captopril test was performed. For comparison of a continuous variable between subjects with a positive MRA and those with a negative MRA, the Mann-Whitney test was used. For comparison of a discrete variable between subjects with a positive MRA and those with a negative MRA, Fisher's exact test was used. RESULTS: The prevalence of RAS detected by using MRA in 117 hypertensive type 2 diabetic subjects was 17%; 19 subjects had unilateral RAS, and only 1 subject had bilateral RAS. A femoral bruit was significantly more common in subjects with a positive MRA versus subjects with a negative MRA (21 vs. 0%; Fisher's exact test P < 0.005); however, other clinical features of atherosclerotic disease were not statistically associated. Greater duration of hypertension and treatment with statins were features of subjects with RAS (P < 0.05). The captopril test was negative in all subjects, although the antihypertensive response to oral captopril was significantly greater in subjects with RAS detected by MRA. CONCLUSIONS: RAS is common in hypertensive type 2 diabetic subjects. The presence of a femoral bruit is a useful predictive clinical marker. The captopril test is not useful in predicting the hemodynamic significance of RAS in this patient group.

Ultrasound-guided trans-rectal high-intensity focused ultrasound (HIFU) for advanced cervical cancer ablation is feasible: a case report.

INTRODUCTION: High-intensity focused ultrasound (HIFU) is an ablative treatment undergoing assessment for the treatment of benign and malignant disease. We describe the first reported intracavitary HIFU ablation for recurrent, unresectable and symptomatic cervical cancer. CASE DESCRIPTION: A 38 year old woman receiving palliative chemotherapy for metastatic cervical adenocarcinoma was offered ablative treatment from an intracavitary trans-rectal HIFU device (Sonablate® 500). Pre-treatment symptoms included vaginal bleeding and discharge that were sufficient to impede her quality of life. No peri-procedural adverse events occurred. Symptoms resolved completely immediately post-procedure, reappeared at 7 days, increasing to pre-procedural levels by day 30. DISCUSSION AND EVALUATION: This first time experience of intracavitary cervical HIFU suggests that it is feasible for palliation of advanced cervical cancer, with no early evidence of unexpected toxicity. Ethical approval had also been granted for the use of per-vaginal access if appropriate. This route, alone or in combination with the rectal route, may provide increased accessibility in future patients with a redesigned device more suited to trans-vaginal ablations. CONCLUSION: Intracavitary HIFU is a potentially safe procedure for the treatment of cervical cancer and able to provide symptomatic improvement in the palliative setting.

The effect of in-plane arterial curvature on blood flow and oxygen transport in arterio-venous fistulae.

Arterio-Venous Fistulae (AVF) are the preferred method of vascular access for patients with end stage renal disease who need hemodialysis. In this study, simulations of blood flow and oxygen transport were undertaken in various idealized AVF configurations. The objective of the study was to understand how arterial curvature affects blood flow and oxygen transport patterns within AVF, with a focus on how curvature alters metrics known to correlate with vascular pathology such as Intimal Hyperplasia (IH). If one subscribes to the hypothesis that unsteady flow causes IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto the outer-curvature of a curved artery. However, if one subscribes to the hypothesis that low wall shear stress and/or low lumen-to-wall oxygen flux (leading to wall hypoxia) cause IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto a straight artery, or the inner-curvature of a curved artery. We note that the recommendations are incompatible-highlighting the importance of ascertaining the exact mechanisms underlying development of IH in AVF. Nonetheless, the results clearly illustrate the important role played by arterial curvature in determining AVF hemodynamics, which to our knowledge has been overlooked in all previous studies.

Tc-99m DTPA scans in renal allograft rejection and cyclosporine nephrotoxicity.

Renal allograft dysfunction arising from rejection or cyclosporine (CsA) nephrotoxicity can currently only be distinguished reliably by allograft biopsy. We have assessed Technetium (Tc)-99m diethylamine pentacetic acid (DTPA) scanning in 30 CsA-treated patients with allograft dysfunction. Scintigrams were performed during 20 biopsy-proved episodes of rejection and during 14 episodes of CsA nephrotoxicity. These results were compared with the scintigrams of 15 allografts showing stable function. Quantitative indices expressing allograft perfusion (flow index) and function (uptake index) derived from the DTPA scintigrams showed no significant differences between the groups of patients with rejection, CsA nephrotoxicity, or stable or improving function. Similarly, the flow and uptake indices of individual allografts obtained during periods of stable or improving function and then during episodes of dysfunction due to rejection or CsA nephrotoxicity did not significantly change. We conclude that Tc-99m DTPA scintigrams are of limited value in the management of allograft dysfunction in patients immunosuppressed with CsA.

Magnetic resonance angiography of renal arteries.

Magnetic resonance angiography has very exciting potential for the investigation of renal artery stenosis. This article discusses what exact techniques are optimal and current information suggests that 3-D phase contrast sequences are probably the best that are currently available for this role. Magnetic resonance imaging techniques provide instantly recognizable images and generally are more acceptable than other modalities. In addition, the current study suggests a very promising sensitivity and specificity for the determination of renal artery stenosis.

MRI of the claustrophobic patient: interventionally configured magnets.

The aim of this study was to determine whether or not claustrophobic patients would tolerate a scan in an open configuration interventional magnetic resonance (iMR) imaging unit, when they had failed to complete a diagnostic scan in a conventional MRI system. 50 claustrophobic subjects were entered into the study. Their response to the iMR environment was compared with their previous experience in an MRI scanner by means of a two-stage questionnaire. Part 1 was completed before their iMR scan and Part 2 following their attempt at imaging in the iMR unit. 60% (n = 30) of the participants were female and 40% (n = 20) were male, age range 25-71 years (mean 49.5 years). 48% (n = 24) were lumbar spine studies and 28% (n = 14) were studies of the head. 24% (n = 12) underwent scanning of other anatomical regions. 94% (n = 47) of participants underwent successful MRI in the interventional magnet without extra sedation. 6% (n = 3) failed to complete a diagnostic scan in the iMR machine. The GE Signa 0.5 T SP magnet allows successful MRI in 94% of the claustrophobic population who have failed to complete a scan in a conventional diagnostic machine.

Interventional magnetic resonance imaging.

The development of minimally invasive surgical and interventional techniques has created a need for more accurate and sensitive image guidance and monitoring. Magnetic resonance imaging, with its superior soft tissue discrimination and multiplanar facilities, seems the obvious choice for an ideal image-guidance tool. Until recently, the employment of MRI in this role has been prevented by the physical constraints of conventional, closed-configuration machines. The problem has now been overcome by the development of an open design allowing both horizontal and vertical access to the patient in the scanner so that procedures can be performed concurrent with image acquisition. This configuration, together with the use of fast gradient echo sequences which can scan at speeds close to real time, means that a wide range of interventional procedures can be performed with on-line image guidance and monitoring. In addition, the versatility of the open design means that patients can assume physiological positions to allow dynamic joint imaging to be performed. This opens up a whole new field in the understanding of joint pathophysiology. This review article discusses these recent technological developments and their clinical applications. In particular, the potential role in guidance of biopsies, monitoring of thermal ablation techniques and applications in endoscopic surgery is outlined.

Case report: renal transplant artery stenosis--three cases where magnetic resonance angiography was superior to conventional arteriography.

Stenosis of renal transplant arteries is a common cause of graft dysfunction and hypertension. Conventionally it is investigated by intraarterial digital subtraction angiography (IA DSA). Recently three-dimensional phase contrast magnetic resonance angiography (MRA) has been used successfully as a non-invasive method of assessing renal transplant arteries. We report three cases where MRA was superior to IA DSA in the detection of renal transplant artery stenosis.