David A. Woodrum

Magnetic resonance-guided focused ultrasound of uterine leiomyomas: review of a 12-month outcome of 130 clinical patients.

PURPOSE To assess 12-month outcomes and safety of clinical magnetic resonance (MR)-guided focused ultrasound (US) treatments of uterine leiomyomas. MATERIALS AND METHODS Between March 2005 and December 2009, 150 women with symptomatic uterine leiomyomas were clinically treated with MR-guided focused US at a single institution; 130 patients completed treatment and agreed to have their data used for research purposes. Patients were followed through retrospective review of medical records and phone interviews conducted at 3-, 6-, and 12-month intervals after treatment to assess additional procedures and symptom relief. Outcome measures and treatment complications were analyzed for possible correlations with the appearance of the tumors on T2-weighted imaging. RESULTS The cumulative incidence of additional tumor-related treatments 12 months after MR-guided focused US was 7.4% by the Kaplan-Meier method. At 3-, 6-, and 12-month follow-up, 86% (90 of 105), 93% (92 of 99), and 88% (78 of 89) of patients reported relief of symptoms, respectively. No statistically significant correlation between tumor appearance on T2-weighted imaging and 12-month outcome was found. Treatment-related complications were observed in 17 patients (13.1%): 16 patients had minor complications and one had a major complication (deep vein thrombosis). All complications were resolved within the 12-month follow-up period. CONCLUSIONS MR-guided focused US is a noninvasive treatment option that can be used to effectively and safely treat uterine leiomyomas and delivers significant and lasting symptom relief for at least 12 months. The incidence of additional treatment during this time period is comparable with those in previous reports of uterine artery embolization.

A Clinical Review of Focused Ultrasound Ablation With Magnetic Resonance Guidance: An Option for Treating Uterine Fibroids

Uterine fibroids are common smooth muscle tumors, which can result in substantial symptoms affecting the quality of life of women. Whereas patients have several options available for treatment, focused ultrasound ablation is one of the least invasive treatment options outside medical therapy. Magnetic resonance-guided focused ultrasound (MRgFUS) ablation combines therapy delivered by an ultrasound transducer with imaging, guidance for therapy, and thermal feedback provided by magnetic resonance imaging. In 2004, the MRgFUS system ExAblate 2000 (InSightec, Haifa, Israel) was approved by the United States Food and Drug Administration for clinical treatments of uterine fibroids. Since its approval, our institution has performed more than 140 treatments. This paper provides an overview of our sites clinical experience with MRgFUS, including a brief description of the treatment system, pertinent features to review on screening magnetic resonance imaging, how the procedure is performed, and risks and benefits of the treatment. Some potential clinical applications of the technology are also briefly reviewed.

Percutaneous Renal Cryoablation: Local Control at Mean 26 Months of Followup

PURPOSE We retrospectively determined the efficacy of percutaneous renal cryoablation based on a mean followup of more than 2 years. MATERIALS AND METHODS Institutional review board approval was obtained for this Health Insurance Portability and Accountability Act compliant retrospective study. Informed consent was waived. From March 2003 through March 2007, 91 patients with 93 tumors underwent 92 percutaneous cryoablation procedures. Technical success was defined as extension of the ice ball beyond the tumor margin and post-ablation images showing no contrast enhancement in the area encompassing the original tumor within 3 months of the procedure. Local tumor progression was defined as new enhancement in the ablated tumor or an increase in ablated tumor size beyond 3 months after the procedure. Complications were defined using the National Cancer Institute Common Terminology Criteria for Adverse Events v3.0. RESULTS Mean followup was 26 months (range 5 to 61, SD ±13) and mean tumor size was 3.4 cm (range 1.5 to 7.3, SD ±1.2). Major complications occurred in 6 of 91 patients (7%) or after 8 of 92 (9%) procedures. Technically successful ablation was performed in the treatment of 89 of the 93 (96%) tumors or 87 of the 91 patients (96%). Of the 83 tumors with followup longer than 3 months only a single case (1%) of local tumor progression occurred. Overall local control was achieved in 86 of 91 (95%) patients or 88 of 93 (95%) tumors. CONCLUSIONS Midterm followup of percutaneous renal cryoablation shows durability of this treatment method with a low incidence of tumor recurrence beyond 3 months.

Percutaneous Cryoablation of Musculoskeletal Oligometastatic Disease for Complete Remission

PURPOSE To assess the safety and effectiveness of percutaneous cryoablation to treat limited metastases to the musculoskeletal system, with the goal of complete disease remission. MATERIALS AND METHODS In a single-institution retrospective study of data from December 2003 to October 2011, 43 consecutive patients underwent initial cryoablation of limited (five or fewer) musculoskeletal metastases with the goal of complete disease remission (ie, no clinical or radiographic evidence of disease). Three patients were lost to follow-up. As a result, the present report describes 40 patients who underwent 40 cryoablation procedures to treat 52 tumors. RESULTS Local control was achieved in 45 of 52 tumors (87%; 95% confidence interval [CI], 75%-93%) at a median follow-up of 21 months (range, 4-62 mo). Thirteen of 19 treated bone metastases (68%) and 32 of 33 soft-tissue metastases (97%) showed local control (P = .007). One- and 2-year overall survival rates were 91% (95% CI, 75%-97%) and 84% (95% CI, 65%-93%), respectively. Median overall survival was 47 months (95% CI, 26-62 mo). One- and 2-year disease-free survival rates were 22% (95% CI, 11%-37%) and 7% (95% CI,<1% to 26%), respectively. Median disease-free survival was 7 months (95% CI, 5-10 mo). Two of 40 procedures (5%) were associated with major complications. CONCLUSIONS Percutaneous cryoablation is a safe and effective treatment to achieve local tumor control and short-term complete disease remission in patients with limited metastatic disease to the musculoskeletal system.

Non‐contrast renal artery MRA using an inflow inversion recovery steady state free precession technique (Inhance): Comparison with 3D contrast‐enhanced MRA

To assess the performance of a three‐dimensional (3D) non‐contrast respiratory‐triggered steady state free precession (SSFP) pulse sequence for detection of renal artery stenosis.

MR-guided focused ultrasound for the treatment of uterine fibroids.

Magnetic resonance imaging–guided focused ultrasound (MRgFUS) ablation of uterine fibroids provides a minimally invasive outpatient technique for targeting and treating symptomatic uterine fibroids. Magnetic resonance imaging provides a guidance platform that has high temporal and spatial resolution for guiding, as well as thermal monitoring of the procedure. The high-intensity focused ultrasound provides a mechanism for delivering large amounts of energy directly into the fibroid without causing detrimental effects to the nontarget tissues. Early and intermediate follow-up of patients treated with MRgFUS provided promising results on the efficacy of the technique for providing symptom relief to patients. As more long-term follow-up data are published, the efficacy of this technique can be compared to more invasive surgical and minimally invasive catheter treatments.

Vascular wall elasticity measurement by magnetic resonance imaging.

The goal of this current study was to determine whether an MRI‐based elastography (MRE) method can visualize and assess propagating mechanical waves within fluid‐filled vessels and to investigate the feasibility of measuring the elastic properties of vessel walls and quantitatively assessing stenotic lesions by using MRE. The ability to measure the Youngs modulus‐wall thickness product was tested using a thin‐walled latex vessel model. Also tested in vessel models was the ability to quantitate the degree of stenosis by measuring transmitted and reflected mechanical waves. This method was then applied to ex vivo porcine models and in vivo human arteries to further test its feasibility. The results provide preliminary evidence that MRE can be used to quantitatively assess the stiffness of blood vessels, and provide a non‐morphologic method to measure stenosis. With further development, it is possible that the method can be implemented in vivo. Magn Reson Med, 2006. Published 2006 Wiley‐Liss, Inc.

The rat femoral arteriovenous fistula model: increased expression of matrix metalloproteinase-2 and -9 at the venous stenosis.

PURPOSE To determine whether a femoral arteriovenous (AV) fistula model in a rat was feasible and whether there is increased expression of matrix metalloproteinase (MMP)-2 and -9 and the tissue inhibitors of MMPs (TIMPs) at the venous stenosis of the fistula. MATERIALS AND METHODS Fifteen male Sprague-Harley rats weighing 353 g +/- 26 underwent creation of an AV fistula between the left femoral artery and ipsilateral femoral vein, with the contralateral femoral vessels serving as controls. The animals were euthanized at day 14 (n = 5) and day 28 (n = 10) after fistula creation. Zymography and Western blot analysis for TIMP-1 and TIMP-2 were performed at the venous stenosis and in control vessels. Hematoxylin and eosin, Verhoeff-van Gieson, Masson trichrome, and alpha-smooth muscle staining were performed at the stenosis and in controls at day 28 in four animals. The intima/media ratio was determined at day 28. RESULTS By day 14, pro-MMP-2 measurements were 8.13 +/- 1.06 at the venous stenosis and 4.1 +/- 1.33 in controls (P < .05). By day 28, they had increased to 18.95 +/- 4.8 at the stenosis and 12.11 +/- 4.84 in controls (P < .05). By day 14, active MMP-2 measurements were 7.38 +/- 1.25 at the stenosis and 2.31 +/- 1.04 in controls (P < .05). By day 28, they had increased to 12.12 +/- 3.45 at the stenosis and 9.26 +/- 3.97 in controls (P < .05). By day 28, pro-MMP-9 measurements were 11.77 +/- 4.71 at the stenosis and 7.78 +/- 3.49 in controls (P < .05), with no difference at day 14. There was no difference in expression of TIMP-1 and TIMP-2. The average intima/media ratio of the stenosis increased by 28% versus controls, and the neointima was composed of primarily alpha-smooth muscle actin-positive cells. CONCLUSIONS A rat femoral AV fistula model was created with venous stenosis formation characterized by thickened neointima composed of alpha-smooth muscle actin-positive cells compared with controls. At the venous stenosis, there was increased expression of pro-MMP-2 and active MMP-2 by days 14 and 28, with significantly increased expression of pro-MMP-9 by day 28.

MR elastography of the in vivo abdominal aorta: a feasibility study for comparing aortic stiffness between hypertensives and normotensives.

To demonstrate feasibility of using MR elastography (MRE) to identify hypertensive changes in the abdominal aorta when compared with normotensives based on the stiffness measurements.

MRI After Technically Successful Renal Cryoablation: Early Contrast Enhancement as a Common Finding

OBJECTIVE The purpose of this study was to assess the MRI appearance and enhancement of renal masses within 36 hours after cryoablation. MATERIALS AND METHODS From March 2003 through January 2008, 129 patients underwent imaging-guided cryoablation for renal masses. Twenty-three of these patients underwent MRI within 36 hours after ablation. During MRI, acquisition of axial T1- and T2-weighted images was followed by administration of a gadolinium contrast agent. Standard follow-up included MRI 3-6 months after ablation. RESULTS Eight of the 23 renal masses imaged within 6-36 hours after ablation were enhanced on MR images. Five of the eight lesions exhibited homogeneous enhancement, and the other three had heterogeneous or rim enhancement. Seven of the eight lesions exhibited no enhancement at the 6-month follow-up examination. One patient underwent follow-up imaging 10 months rather than 3-6 months after the procedure, but no enhancement was seen. T2-weighted signal intensity was mixed among the 23 renal masses. T1-weighted signal intensity was mixed among the 23 renal masses and the eight lesions that became enhanced, but there was a trend for higher T1 signal intensity at the 3- to 6-month follow-up examination. CONCLUSION The high proportion of enhancing lesions 3 months after treatment and the resolution of enhancement 6 months afterward suggest that it may be reasonable to wait 6 months after technically successful renal cryoablation before performing contrast-enhanced MRI.