Joel P Felmlee

Mayo Clinic - Rochester, Рочестер, Minnesota, United States

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Publications (192)602.58 Total impact

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    ABSTRACT: MRI of the peripheral nerves continues to grow technologically and in clinical use. This article reviews the technological aspects and basic interpretation of high-resolution MR imaging of the upper extremity nerves. These techniques work with 1.5-, or preferably 3-T, scanners regardless of vendors. The article also includes selected pitfalls in the interpretation of upper extremity nerve MRI. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
    Seminars in musculoskeletal radiology 04/2015; 19(2):160-167. DOI:10.1055/s-0035-1545078 · 0.95 Impact Factor
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    ABSTRACT: MRI in patients with LV leads may cause tissue or lead heating, dislodgement, venous damage, or lead dysfunction.Objective Determine the safety of MRI in patients with LV pacing leads.Methods Prospective data were collected in patients with CS LV leads undergoing clinically indicated MRI at 3 institutions. Patients were not pacemaker dependent. Scans were performed under pacing nurse, technician, radiologist, and physicist supervision using continuous vital sign, pulse oximetry, and ECG monitoring and a 1.5 T scanner with SAR < 1.5 Watts/kg. Devices were interrogated pre- and post-MRI, programmed to asynchronous or inhibition mode with tachyarrhythmia therapies off (if present) and reprogrammed to their original settings post-MRI.ResultsMRI scans (n=42) were performed in 40 patients with non-MRI conditional LV leads between 2005-2013 (mean age 67 ± 9 years, n=16 or 40% women, median lead implant duration 740 days with IQ range 125-1173 days). MRIs were performed on the: head/neck/spine (n=35, 83%), lower extremities (n=4, 10%), chest (n=2, 5%), and abdomen (n=1, 2%). There were no overall differences in pre- and post-MRI interrogation LV lead sensing (12.4 ± 6.2 vs. 12.9 ± 6.7 mV, p=0.38), impedance (724 ± 294 vs. 718 ± 312 Ohms, p=0.67), or threshold (1.4 ± 1.1 vs. 1.4 ± 1.0 V, p=0.91). There were no individual LV lead changes requiring intervention.ConclusionMRI scanning was performed safely in non-pacemaker dependent patients with CS LV leads who were carefully monitored during imaging without clinically significant adverse effect on LV lead function.
    Heart Rhythm 11/2014; 12(2). DOI:10.1016/j.hrthm.2014.11.037 · 4.92 Impact Factor
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    ABSTRACT: Cine Phase Contrast (CPC) MRI offers unique insight into localized skeletal muscle behavior by providing the ability to quantify muscle strain distribution during cyclic motion. Muscle strain is obtained by temporally integrating and spatially differentiating CPC-encoded velocity. The aim of this study was to quantify measurement accuracy and precision and to describe error propagation into displacement and strain. Using an MRI-compatible jig to move a B-gel phantom within a 1.5T MRI bore, CPC-encoded velocities were collected. The three orthogonal encoding gradients (through plane, frequency, and phase) were evaluated independently in post-processing. Two systematic error types were corrected: eddy current-induced bias and calibration-type error. Measurement accuracy and precision were quantified before and after removal of systematic error. Through plane- and frequency-encoded data accuracy were within 0.4 mm/s after removal of systematic error – a 70% improvement over the raw data. Corrected phase-encoded data accuracy was within 1.3 mm/s. Measured random error was between 1 to 1.4 mm/s, which followed the theoretical prediction. Propagation of random measurement error into displacement and strain was found to depend on the number of tracked time segments, time segment duration, mesh size, and dimensional order. To verify this, theoretical predictions were compared to experimentally calculated displacement and strain error. For the parameters tested, experimental and theoretical results aligned well. Random strain error approximately halved with a two-fold mesh size increase, as predicted. Displacement and strain accuracy were within 2.6 mm and 3.3%, respectively. These results can be used to predict the accuracy and precision of displacement and strain in user-specific applications.
    Journal of Biomechanics 11/2014; 48(1). DOI:10.1016/j.jbiomech.2014.10.035 · 2.50 Impact Factor
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    ABSTRACT: Magnetic resonance imaging (MRI) has been safely performed in some patients with cardiac implantable electronic devices (CIEDs) under careful protocols. Pacemaker dependent patients are often excluded, in part due to concern of "power-on reset" (PoR), which can result in a change from asynchronous to inhibited pacing with consequent inhibition of pacing due to noise from the MRI. We reviewed risk factors for PoR during MRI. Prospective data were collected starting in 2008 in patients with CIEDs undergoing clinically indicated MRI. Eligible patients were not pacemaker dependent. Devices were interrogated pre- and post-MRI, programmed to asynchronous pacing or inhibition mode with tachyarrhythmia therapies off, and reprogrammed to their original settings post-MRI. MRI scans (n=256) were performed in 198 patients with non-MRI conditional CIEDs between 2008-2013 (median age 66, IQ 57-77; 59% men). PoR occurred during 9 MRI scans (3.5%) in 8 patients. PoR was more frequent with Medtronic devices than other generator brands (n=9/139 vs. 0/117, 6% vs. 0%, p=0.005). Devices with PoR were all released before 2002 and were implanted from 1999 to 2004. Effects of PoR included a decrease in heart rate during MRI (n=4) and transient anomalous battery life indication (n=1). All devices functioned normally following MRI. PoR occurs infrequently but can cause deleterious changes to pacing mode and heart rate. MRI scans should not be performed in pacemaker dependent patients with older, at risk generators. Continuous monitoring during MRI is essential as unrecognized PoR may inhibit pacing or accelerate power depletion due to high pacing output. Copyright © 2014. Published by Elsevier Inc.
    Heart rhythm: the official journal of the Heart Rhythm Society 11/2014; 12(3). DOI:10.1016/j.hrthm.2014.10.039 · 4.92 Impact Factor
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    ABSTRACT: Introduction of urethral warmers to aid cryosurgery in the prostate has significantly reduced the incidence of urethral sloughing; however, the incidence rate still remains as high as 15%. Furthermore, urethral warmers have been associated with an increase of cancer recurrence rates. Here, we report results from our phantom-based investigation to determine the impact of an urethral warmer on temperature distributions around cryoneedles during cryosurgery. Cryoablation treatments were simulated in a tissue mimicking phantom containing an urethral warming catheter. Four different configurations of cryoneedles relative to urethral warming catheter were investigated. For each configuration, the freeze-thaw cycles were repeated with and without the urethral warming system activated. Temperature histories were recorded at various pre-arranged positions relative to the cryoneedles and urethral warming catheter. In all configurations, the urethral warming system was effective at maintaining sub-lethal temperatures at the simulated surface of the urethra. The warmer action, however, was additionally demonstrated to potentially negatively impact treatment lethality in the target zone by elevating minimal temperatures to sub-lethal levels. In all needle configurations, rates of freezing and thawing were not significantly affected by the use of the urethral warmer. The results indicate that the urethral warming system can protect urethral tissue during cryoablation therapy with cryoneedles placed as close as 5 mm to the surface of the urethra. Using an urethral warming system and placing multiple cryoneedles within 1 cm of each other delivers lethal cooling at least 5 mm from the urethral surface while sparing urethral tissue.
    Cryobiology 08/2014; DOI:10.1016/j.cryobiol.2014.06.004 · 1.64 Impact Factor
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    ABSTRACT: Background Functional magnetic resonance imaging (fMRI) is a powerful method for identifying in vivo network activation evoked by deep brain stimulation (DBS). Objective Identify the global neural circuitry effect of subthalamic nucleus (STN) DBS in nonhuman primates (NHP). Method An in-house developed MR image-guided stereotactic targeting system delivered a mini-DBS stimulating electrode, and blood oxygenation level-dependent (BOLD) activation during STN DBS in healthy NHP was measured by combining fMRI with a normalized functional activation map and general linear modeling. Results STN DBS significantly increased BOLD activation in the sensorimotor cortex, supplementary motor area, caudate nucleus, pedunculopontine nucleus, cingulate, insular cortex, and cerebellum (FDR < 0.001). Conclusion Our results demonstrate that STN DBS evokes neural network grouping within the motor network and the basal ganglia. Taken together, these data highlight the importance and specificity of neural circuitry activation patterns and functional connectivity.
    Brain Stimulation 07/2014; 7(4). DOI:10.1016/j.brs.2014.04.007 · 5.43 Impact Factor
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    ABSTRACT: Purpose: Several institutions have developed MRI guidelines for patients with MR-unsafe or MR-conditional pacemakers. Here we highlight the role of a medical physicist in implementing these guidelines for non-pacemaker dependent patients. Guidelines: Implementing these guidelines requires involvement from several medical specialties and a strong collaboration with the site MRI supervisor to develop a structured workflow. A medical physicist is required to be present during the scan to supervise the MR scanning and to maintain a safety checklist that ensures: 1) uninterrupted patient communication with the technologist, 2) continuous patient physiologic monitoring (e.g. blood pressure and electrocardiography) by a trained nurse, 3) redundant patient vitals monitoring (e.g. pulse oximetry) due to the possibility of in vivo electrocardiography reading fluctuations during image acquisition. A radiologist is strongly recommended to be available to review the images before patients are discharged from the scanner. Pacemaker MRI should be restricted to 1.5T field strength. The MRI sequences should be optimized by the physicist with regards to: a) SAR: limited to <1.5 W/Kg for MR-unsafe pacemakers in normal operating mode, b) RF exposure time: <30 min, c) Coils: use T/R coils but not restricted to such, d) Artifacts: further optimization of sequences whenever image quality is compromised due to the pacemaker. In particular, cardiac, breast and left-shoulder MRIs are most susceptible to these artifacts. Possible strategies to lower the SAR include: a) BW reduction, 2) echo-train-length reduction, 3) increase TR, 4) decrease number of averages, 5) decrease flip angle, 6) reduce slices and/or a combination of all the options.
    Medical Physics 06/2014; 41(6):121-121. DOI:10.1118/1.4887914 · 3.01 Impact Factor
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    ABSTRACT: Clinical diagnostic medical physicists may be responsible for implementing and maintaining a comprehensive MR safety program. Accrediting bodies including the ACR, IAC, Radsite and The Joint Commission each include aspects of MR Safety into their imaging accreditation programs; MIPPA regulations further raise the significance of non-compliance. In addition, The Joint Commission recently announced New and Revised Diagnostic Imaging Standards for accredited health care organizations which include aspects of MR Safety. Hospitals and clinics look to the physicist to understand guidelines, regulations and accreditation requirements related to MR safety. The clinical medical physicist plays a significant role in a clinical practice by understanding the physical basis for the risks and acting as a facilitator to successfully implement a safety program that provides well-planned siting, allows for the safe scanning of certain implanted devices, and helps radiologists manage specific patient exams. The MRI scanning of specific devices will be discussed including cardiac pacemakers and neurostimulators such as deep brain stimulators. Furthermore for sites involved in MR guided interventional procedures, the MR physicist plays an essential role to establish safe practices. Creating a framework for a safe MRI practice includes the review of actual safety incidents or close calls to determine methods for prevention in the future. Learning Objectives: 1. Understand the requirements and recommendations related to MR safety from accrediting bodies and federal regulations. 2. Understand the Medical Physicist&apos;s roles to ensure MR Safety. 3. Identify best practices for dealing with implanted devices, including pacemakers and deep brain stimulators. 4. Review aspects of MR safety involved in an MR guided interventional environment. 5. Understand the important MR safety aspects in actual safety incidents or near misses.
    Medical Physics 06/2014; 41(6):546-546. DOI:10.1118/1.4889584 · 3.01 Impact Factor
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    ABSTRACT: IntroductionAbandoned cardiovascular implantable electronic device (CIED) leads remain a contraindication to magnetic resonance imaging (MRI) studies, largely due to in vitro data showing endocardial heating secondary to the radiofrequency field. We tested the hypothesis that abandoned CIED leads do not pose an increased risk of clinical harm for patients undergoing MRI.Methods This single-center retrospective study examined the outcomes of patients who had device generators removed before MRI, rendering the device leads abandoned. Information was gathered through chart review. Data collected included lead model, pacing threshold before MRI, anatomic region examined, threshold data after generator reimplantation, and clinical patient outcome.ResultsPatients (n = 19, 11 men and eight women) ranged in age from 19 to 85 at the time of MRI. There was a mean of 1.63 abandoned leads at the time of imaging; none of the leads were MRI conditional. Of the three implantable cardioverter defibrillator (ICD) leads, two of three were dual coil. Most (31/35) of the scans performed were of the central nervous system, including head and spinal imaging. There were no adverse events associated with MRI in any of these patients with abandoned leads within 7 days of the scan. No lead malfunctions or clinically significant change in pacing thresholds were noted with generator reimplantation.Conclusion The use of MRI in patients with abandoned cardiac device leads appears feasible when performed under careful monitoring, with no adverse events, although the experience is small. MRI did not affect the function of leads that were subsequently reconnected to a cardiac device.
    Pacing and Clinical Electrophysiology 05/2014; 37(10). DOI:10.1111/pace.12419 · 1.25 Impact Factor
  • Journal of Vascular and Interventional Radiology 03/2014; 25(3):S137. DOI:10.1016/j.jvir.2013.12.369 · 2.15 Impact Factor
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    Journal of the American College of Radiology: JACR 01/2014; 11(1):94-6. DOI:10.1016/j.jacr.2013.09.024 · 2.28 Impact Factor
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    ABSTRACT: Radiofrequency (RF) shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI) examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (∼1 dB) of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices.
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    ABSTRACT: To develop a reliable magnetic resonance elastography (MRE)-based method for measuring regional brain stiffness. First, simulation studies were used to demonstrate how stiffness measurements can be biased by changes in brain morphometry, such as those due to atrophy. Adaptive postprocessing methods were created that significantly reduce the spatial extent of edge artifacts and eliminate atrophy-related bias. Second, a pipeline for regional brain stiffness measurement was developed and evaluated for test-retest reliability in 10 healthy control subjects. This technique indicates high test-retest repeatability with a typical coefficient of variation of less than 1% for global brain stiffness and less than 2% for the lobes of the brain and the cerebellum. Furthermore, this study reveals that the brain possesses a characteristic topography of mechanical properties, and also that lobar stiffness measurements tend to correlate with one another within an individual. The methods presented in this work are resistant to noise- and edge-related biases that are common in the field of brain MRE, demonstrate high test-retest reliability, and provide independent regional stiffness measurements. This pipeline will allow future investigations to measure changes to the brain's mechanical properties and how they relate to the characteristic topographies that are typical of many neurologic diseases.
    PLoS ONE 12/2013; 8(12):e81668. DOI:10.1371/journal.pone.0081668 · 3.53 Impact Factor
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    ABSTRACT: To establish the feasibility of magnetic resonance imaging (MRI)-guided cryoablation in patients with previous radical prostatectomy and MRI visualized biopsy-proven local recurrence of prostate adenocarcinoma. Eighteen postprostatectomy patients (mean 67, 57-78 years) were treated with MRI-guided cryoablation for recurrent prostate carcinoma. Patients were found to have a hyperenhancing nodule using multiparametric MRI with endorectal coil followed by a positive transrectal ultrasound-guided biopsy. Of 18 postsurgical patients, 6 had additional salvage external beam radiation with subsequent recurrence. Under general anesthesia and MRI guidance (wide-bore 1.5T MRI), 2-5 cryotherapy probes were placed in or around the recurrence by transperineal approach and cryoablation performed. The patients were stratified into 2 groups: the initial 9 consecutive patients had cryoprobes placed 1 cm apart with 2 freeze-thaw cycles (group 1), and the subsequent 9 patients had cryoprobes placed 0.5 cm apart with 3 freeze-thaw cycles (group 2). In group I, the average preprocedure prostate-specific antigen (PSA) was 1.21 ± 1.12 ng/mL, and 1-3 months postprocedure PSA was 0.14 ± 0.11 ng/mL (P <.01). Sixty-seven percent of patients had PSA ≤0.2 ng/mL at 1-3 months follow-up, but only 25% at 4-6 months. No change in impotence or incontinence occurred. In group II, average preprocedure PSA was 2.24 ± 2.71 ng/mL, and 1-3 month postprocedure PSA was 0.08 ± 0.10 ng/mL (P <.05). Eighty-nine percent of patients had PSA ≤0.2 ng/mL at 1-3 months follow-up and at 4-6 months. Complications in group 2 included worsening incontinence in 3 patients. MRI-guided salvage cryoablation of postradical prostatectomy prostate cancer recurrence is safe and feasible. Both techniques produce early PSA decrease with more lasting PSA results in the more aggressive group II methodology.
    Urology 08/2013; 82(4). DOI:10.1016/j.urology.2013.06.011 · 2.13 Impact Factor
  • Journal of the American College of Radiology: JACR 07/2013; 10(9). DOI:10.1016/j.jacr.2013.05.029 · 2.28 Impact Factor
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    ABSTRACT: Recent studies have shown that magnetic resonance imaging (MRI) of patients with pacemakers can be safely performed under careful monitoring, but they excluded patients with recently implanted devices. Patients with recent implants may be at a greater risk for complications during MRI imaging due to lack of lead and wound maturity. We implemented a clinical protocol for MRI imaging of patients with implanted cardiac devices, and prospectively collected data. For this study, we retrospectively analyzed two groups of patients: those with recently implanted (≤42 days) and nonrecently implanted (>42 days) leads at the time of MRI scanning. All devices were interrogated before and after scanning, and were reprogrammed during the scan as per protocol. Of the 219 scans (in 171 patients), eight included patients with recently implanted (range: 7-36 days) and 211 with only nonrecently implanted pacemaker leads. During the scan, there were no complications in the early or late group. In one patient imaged 79 days postimplant, frequent premature ventricular complexes were noted during the scan, requiring no action. No patient reported pain during or immediately after the procedure. No clinically significant changes in function were seen at subsequent follow up (average 104 days post-MRI). Compared to patients with nonrecently implanted leads, there was no difference in any parameter between the two groups. With a strong clinical indication and with careful monitoring, MRI imaging is feasible in patients with recently implanted pacemakers, although experience is limited.
    Pacing and Clinical Electrophysiology 07/2013; 36(9). DOI:10.1111/pace.12213 · 1.25 Impact Factor
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    ABSTRACT: Purpose: To evaluate a variety of materials that might serve as fiducial markers for abdominal MRI‐ultrasound fusion applications. Methods: Two experiments were performed: (1) in a phantom, a broad set of candidate materials were evaluated based on visibility in spin echo T1 and T2, and gradient echo T1 and T2* MRI pulse sequences; (2) the leading candidates were evaluated using standard clinical abdominal pulse sequences, both in a phantom and volunteer. Experiment 1 evaluated: two commercial fiducial MRI markers (IZI Medical Products and Beekley Medical); vitamin E and fish oil capsules; water; and copper sulfate solution. Experiment 2 evaluated fish oil capsules and copper sulfate solution. In experiment 2, ultrasound coupling gel was also evaluated. Liquids were poured in wells drilled in a plexiglass base. All scanning was performed with a clinical 1.5T GE Signa Excite scanner. For each pulse sequence, maximum intensity projection images (MIPs) were formed, after removing the phantom signals. Visibility was evaluated by rank ordering signal magnitude in the MIPs. Results: In experiment 1, copper sulfate solution and fish oil were superior to the other materials. In experiment 2, ultrasound gel and copper sulfate solution were clearly superior to the other materials, and were easily seen in the all of the phantom and volunteer images. Conclusion: Based on these preliminary experiments, ultrasound gel and copper sulfate solution appear to be the most promising fiducial marker materials for MRI‐ultrasound fusion applications in the abdomen.
    Medical Physics 06/2013; 40(6):141. DOI:10.1118/1.4814179 · 3.01 Impact Factor
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    ABSTRACT: Deep Brain Stimulation (DBS) of the nucleus accumbens (NAc) has previously been investigated clinically for the treatment of several psychiatric conditions, including obsessive-compulsive disorder and treatment resistant depression. However, the mechanism underlying the therapeutic benefit of DBS, including the brain areas that are activated, remains largely unknown. Here, we utilized 3.0 T functional Magnetic Resonance Imaging (fMRI) changes in Blood Oxygenation Level-Dependent (BOLD) signal to test the hypothesis that NAc/internal capsule DBS results in global neural network activation in a large animal (porcine) model Animals (n = 10) were implanted in the NAc/internal capsule with DBS electrodes and received stimulation (1, 3, and 5 V, 130 Hz, and pulse widths of 100 and 500 µsec). BOLD signal changes were evaluated using a gradient echo-echo planar imaging (GRE-EPI) sequence in 3.0 T MRI. We used a normalized functional activation map for group analysis and applied general linear modeling across subjects (FDR<0.001). The anatomical location of the implanted DBS lead was confirmed with a CT scan We observed stimulation-evoked activation in the ipsilateral prefrontal cortex, insula, cingulate and bilateral parahippocampal region along with decrease in BOLD signal in the ipsilateral dorsal region of the thalamus. Furthermore, as the stimulation voltage increased from 3 V to 5 V, the region of BOLD signal modulation increased in insula, thalamus, and parahippocampal cortex and decreased in the cingulate and prefrontal cortex. We also demonstrated that right and left NAc/internal capsule stimulation modulates identical areas ipsilateral to the side of the stimulation Our results suggest that NAc/internal capsule DBS results in modulation of psychiatrically important brain areas notably the prefrontal cortex, cingulate, and insular cortex, which may underlie the therapeutic effect of NAc DBS in psychiatric disorders. Finally, our fMRI setup in the large animal may be a useful platform for translational studies investigating the global neuromodulatory effects of DBS.
    PLoS ONE 02/2013; 8(2):e56640. DOI:10.1371/journal.pone.0056640 · 3.53 Impact Factor
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    ABSTRACT: PURPOSE/AIM MR imaging can be used in evaluating various pathology involving the penis and urethra. Given long course and mobile nature, imaging of these organs is often challenging. The purpose of this study includes 1. To discuss technical challenges and advances to improve image quality. 2. To discuss indications of MR imaging. 3. To demonstrate MR imaging findings of various pathology of the penis and urethra. CONTENT ORGANIZATION 1. Technical Challenges and Improvements When the penis is twisted or bent, image interpretation is challenging. Proper positioning and immobilization of the penis is essential. Use of 3T magnet and surface coil can improve image quality. MR urethrography can be performed by administrating saline or gel into the urethra. 2. Indications MR imaging can be used for evaluating urethral abnormalities including congenital anomalies, traumatic rupture, amyloidosis, and neoplasms, as well as penile abnormalities including fracture, thrombus, Peyronie's disease, vascular malformation, and neoplasms. 3. Imaging Findings MR imaging findings of the various penile and urethral abnormalities will be presented. SUMMARY MR imaging is an excellent modality for evaluating the penile and male urethral pathology. Proper positioning and immobilization and application of surface coil are essential for good quality imaging.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: Object The object of this study was to determine the potential of magnetic resonance elastography (MRE) to preoperatively assess the stiffness of meningiomas. Methods Thirteen patients with meningiomas underwent 3D brain MRE examination to measure stiffness in the tumor as well as in surrounding brain tissue. Blinded to the MRE results, neurosurgeons made a qualitative assessment of tumor stiffness at the time of resection. The ability of MRE to predict the surgical assessment of stiffness was tested using a Spearman rank correlation. Results One case was excluded due to a small tumor size. In the remaining 12 cases, both tumor stiffness alone (p = 0.023) and the ratio of tumor stiffness to surrounding brain tissue stiffness (p = 0.0032) significantly correlated with the surgeons' qualitative assessment of tumor stiffness. Results of the MRE examination provided a stronger correlation with the surgical assessment of stiffness compared with traditional T1- and T2-weighted imaging (p = 0.089), particularly when considering meningiomas of intermediate stiffness. Conclusions In this cohort, preoperative MRE predicted tumor consistency at the time of surgery. Tumor stiffness as measured using MRE outperformed conventional MRI because tumor appearance on T1- and T2-weighted images could only accurately predict the softest and hardest meningiomas.
    Journal of Neurosurgery 10/2012; 118(3). DOI:10.3171/2012.9.JNS12519 · 3.15 Impact Factor

Publication Stats

5k Citations
602.58 Total Impact Points


  • 1990–2015
    • Mayo Clinic - Rochester
      • Department of Radiology
      Рочестер, Minnesota, United States
  • 2002–2004
    • University of Pittsburgh
      • Department of Radiology
      Pittsburgh, PA, United States
  • 1999–2004
    • Mayo Foundation for Medical Education and Research
      • • Department of Radiology
      • • Department of Diagnostic Radiology
      Scottsdale, AZ, United States
  • 2001
    • Center for Magnetic Resonance Research Minnesota, USA
      Minneapolis, Minnesota, United States