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Biomedical subjects

Neil M Rofsky

Publications and source records attributed to Neil M Rofsky.

At least 37 records · Page 2Linked to original sources
PubMed2004

Magnetic resonance mapping of transplanted endothelial progenitor cells for therapeutic neovascularization in ischemic heart disease.

OBJECTIVE: Intramyocardial transplantation of endothelial progenitor cells (EPCs) has been previously correlated with significant augmentation of vascularity and improvement of left ventricular function following myocardial ischemia. However, precise intramyocardial localization of the transplanted cells and the extent of in situ cell migration are unknown. We present a novel technique using magnetic resonance imaging (MRI) to localize transplanted EPCs in ischemic hearts. METHODS: CD34-positive cells were isolated from human peripheral blood by magnetic bead selection: CD34-positive cells adhere to CD34-negative antibody coated magnetic beads, while CD34-negative cells do not. All cells were labeled with fluorescent DiI-dye for histological localization. CD34-positive cells or CD34-negative cells (105, 1 x 106 and 2 x 106 cells) were transplanted into non-ischemic (n = 6) or ischemic myocardium (n = 2) of Sprague-Dawley rats. Rats were sacrificed 24 h after cell transplantation. The resected hearts were imaged ex vivo using 3 and 8.5 T magnets. Morphological correlation between the MRI findings and fluorescent microscopy for identification of retained CD34-positive cells was evaluated. RESULTS: CD34-positive cells were identified as areas of low signal intensity on T2*-weighted images within the myocardium. These areas increased in size with the gradual increase in the echo time due to susceptibility effect. The extent of the low signal intensity at a given echo time was proportional to cell dosage. No areas of low signal were identified in the CD34-negative cell transplanted hearts. Histological localization of DiI-labeled CD34-positive cells documented a direct anatomic correlation with the localization of transplanted cells on the MRI images. CONCLUSIONS: Magnetically labeled EPCs transplanted for therapeutic neovascularization in myocardial ischemia can be visualized with ex vivo MRI at high-field strengths.

Animals↗
PubMed2004

A method for the determination of proximal pulmonary vein size using contrast-enhanced magnetic resonance angiography.

OBJECTIVES: We sought to develop a reproducible method for characterizing the anatomy of the proximal pulmonary veins. BACKGROUND: Contrast-enhanced three-dimensional magnetic resonance angiography (CE-MRA) is a commonly requested test before and after radiofrequency ablation for the treatment of atrial fibrillation. While CE-MRA readily visualizes the pulmonary veins, there is no standardized method for determining their size and cross-sectional anatomy. METHODS: Data for 24 consecutive patients referred for pulmonary vein CE-MRA before an elective ablation procedure for the treatment of atrial fibrillation were analyzed. Detailed measurements of the pulmonary vein diameter, circumference, and cross-sectional area were obtained at three locations: the juncture of the pulmonary vein with the left atrium (LA) (position 1J), the narrowest segment within 5 mm of the juncture (position 2(5mm)), and at the location in the sagittal plane at which the pulmonary veins separate from the LA and from each other (position 3Sag). Intraobserver and interobserver variabilities were also determined for each method. RESULTS: The left lower pulmonary vein was significantly smaller than the other pulmonary veins at positions 1J and 2(5mm) (p<0.05). The right upper pulmonary vein was significantly larger than the other pulmonary vein at position 3Sag (p<0.05). At positions 1J and 2(5mm), the diameter had a low correlation with the circumference and cross-sectional area. At position 3Sag, the major and minor axis dimensions had a very high correlation with the circumference and cross-sectional area. The intraobserver and interobserver variabilities were substantially lower (better) for position 3Sag. CONCLUSIONS: Pulmonary vein diameter measurements are highly variable and do not reflect true anatomic variation in cross-sectional anatomy. A sagittal method of determining pulmonary vein size was highly reproducible and may therefore be advantageous for use in patients likely to need serial examinations.

Adult↗
PubMed2004

MR imaging relaxation times of abdominal and pelvic tissues measured in vivo at 3.0 T: preliminary results.

PURPOSE: To measure T1 and T2 relaxation times of normal human abdominal and pelvic tissues and lumbar vertebral bone marrow at 3.0 T. MATERIALS AND METHODS: Relaxation time was measured in six healthy volunteers with an inversion-recovery method and different inversion times and a multiple spin-echo (SE) technique with different echo times to measure T1 and T2, respectively. Six images were acquired during one breath hold with a half-Fourier acquisition single-shot fast SE sequence. Signal intensities in regions of interest were fit to theoretical curves. Measurements were performed at 1.5 and 3.0 T. Relaxation times at 1.5 T were compared with those reported in the literature by using a one-sample t test. Differences in mean relaxation time between 1.5 and 3.0 T were analyzed with a two-sample paired t test. RESULTS: Relaxation times (mean +/- SD) at 3.0 T are reported for kidney cortex (T1, 1,142 msec +/- 154; T2, 76 msec +/- 7), kidney medulla (T1, 1,545 msec +/- 142; T2, 81 msec +/- 8), liver (T1, 809 msec +/- 71; T2, 34 msec +/- 4), spleen (T1, 1,328 msec +/- 31; T2, 61 msec +/- 9), pancreas (T1, 725 msec +/- 71; T2, 43 msec +/- 7), paravertebral muscle (T1, 898 msec +/- 33; T2, 29 msec +/- 4), bone marrow in L4 vertebra (T1, 586 msec +/- 73; T2, 49 msec +/- 4), subcutaneous fat (T1, 382 msec +/- 13; T2, 68 msec +/- 4), prostate (T1, 1,597 msec +/- 42; T2, 74 msec +/- 9), myometrium (T1, 1,514 msec +/- 156; T2, 79 msec +/- 10), endometrium (T1, 1,453 msec +/- 123; T2, 59 msec +/- 1), and cervix (T1, 1,616 msec +/- 61; T2, 83 msec +/- 7). On average, T1 relaxation times were 21% longer (P <.05) for kidney cortex, liver, and spleen and T2 relaxation times were 8% shorter (P <.05) for liver, spleen, and fat at 3.0 T; however, the fractional change in T1 and T2 relaxation times varied greatly with the organ. At 1.5 T, no significant differences (P >.05) in T1 relaxation time between the results of this study and the results of other studies for liver, kidney, spleen, and muscle tissue were found. CONCLUSION: T1 relaxation times are generally higher and T2 relaxation times are generally lower at 3.0 T than at 1.5 T, but the magnitude of change varies greatly in different tissues.

Abdomen↗
PubMed2003

Shortening MR image acquisition time for volumetric interpolated breath-hold examination with a recently developed parallel imaging reconstruction technique: clinical feasibility.

A recently developed parallel magnetic resonance (MR) imaging technique, parallel imaging with an augmented radius in k space, was used to accelerate the volumetric interpolated breath-hold examination (VIBE) performed in 20 patients referred for clinical liver imaging. Nonaccelerated MR images were also acquired in these patients. A five-point scale was used to score the quality of the images. The acceleration resulted in reduced image quality: The nonaccelerated images had a significantly higher (P <.05) mean score--3.8 +/- 0.3 (SD), indicating good quality--than the accelerated images--3.0 +/- 0.3, indicating acceptable quality. However, for three patients who could not hold their breath for the duration necessary for nonaccelerated imaging, less severe breathing artifacts on the accelerated images resulted in improved quality compared with the quality of the nonaccelerated images. Parallel MR imaging-accelerated VIBE may be beneficial for patients who have difficulty sustaining a breath hold for the duration necessary to perform nonaccelerated imaging.

Adult↗
PubMed2003

Visualization and quantification of renal R2* changes during water diuresis.

PURPOSE: To refine and evaluate methods for analysis of renal blood oxygenation level dependent (BOLD) MRI data. MATERIALS AND METHODS: Color R2* maps and regions-of-interest (ROIs) on the borderline between cortex and medulla were applied to renal BOLD MRI data of a group of 13 young female subjects. RESULTS: The distribution of R2* within the kidneys was heterogeneous and the response of human kidneys to water diuresis was patchy. R2* values at the cortico-medullary border region have a smaller variation than in wider cortical or medullary regions and are sensitive to physiological changes produced by water diuresis. CONCLUSION: These methods provide improved visualization of the regional distribution of R2* and its variations and more precise quantification of the changes in renal R2* produced by water diuresis.

Adult↗
PubMed2003

Double inversion black-blood fast spin-echo imaging of the human heart: a comparison between 1.5T and 3.0T.

PURPOSE: To evaluate the effectiveness of blood suppression and the quality of black-blood cardiac images acquired at 3.0 Tesla using a double-inversion recovery fast spin-echo sequence by comparing data acquired at 3.0T to data acquired at 1.5T. MATERIALS AND METHODS: Black-blood T2-weighted fast spin-echo images of the heart were acquired from five normal volunteers at 1.5T and five normal volunteers at 3.0T. Region-of-interest signal intensity measurements were performed at several locations in the suppressed blood regions of the left and right ventricles and around the left ventricle walls to assess the effectiveness and uniformity of the blood suppression, the myocardial signal-to-noise ratio (SNR), and the signal uniformity at both field strengths. B1 field maps were produced in phantoms and in subjects at both field strengths. RESULTS: Blood suppression performance is equivalent at 1.5T and 3.0T. The improvement in SNR at 3.0T compared with 1.5T is less than has been predicted in previous studies. The signal uniformity is significantly poorer at 3.0T than at 1.5T due to dielectric effects and shorter radio frequency wavelengths (P < 0.005). CONCLUSION: Spin-echo and spin-echo echo-train sequences that perform well at 1.5T will produce large signal variations in the chest cavity at 3.0T without modifications. B1 insensitive methods must be explored and implemented for spin-echo sequences to fully realize the advantages of using these sequences for high-field MRI.

Blood↗
PubMed2003

The interrupted rim sign in acute cholecystitis: a method to identify the gangrenous form with MRI.

We present the imaging findings on MR of a patient with acute gangrenous cholecystitis that demonstrated patchy enhancement of the gallbladder mucosa on gadolinium-enhanced fat-saturated T1-weighted gradient echo images. This interrupted rim of mucosal enhancement correlated with patchy areas of necrosis and inflammation of the gallbladder mucosa on the histopathological examination.

Acute Disease↗
PubMed2003

Breathhold abdominal and thoracic proton MR spectroscopy at 3T.

The clinical utility of proton MR spectroscopy ((1)H-MRS) has been well demonstrated in the brain, prostate, and breast. The aims of this work were to investigate 1) the feasibility of abdominal and thoracic (1)H-MRS at 3T, 2) the benefits of breathholding to MRS in these regions, and 3) the utility of multiple breathhold averaging for MRS. Breathholding either eliminated or markedly reduced phase and frequency shifts and outer voxel contamination that were associated with the motion of the abdomen and the thorax during breathing. Breathholding was found to be essential to spectroscopic investigation of the thorax. Spectra of renal cell carcinoma metastases in the abdomen and thorax were obtained utilizing multiple breathhold averaging. These spectra exhibited a resonance at 3.2 ppm attributed to the trimethylamine moiety of choline metabolites. The results of this study suggest a practical strategy for implementation of (1)H-MRS in the body.

Abdomen↗
PubMed2003

MR techniques for renal imaging.

This article describes the principles, attributes, and pitfalls of the many MR imaging approaches available for assessment of renal-related disorders. Tables 1 and 2 summarize the specific approach and rationale.

Contrast Media↗
PubMed2003

MR imaging in abdominal emergencies.

The use of MR imaging in the emergency setting is evolving. Clear indications include situations in need of contrast media when iodinated contrast cannot be administered or to facilitate assessments in pregnant patients and children when exposure to ionizing radiation is considered unacceptable. The availability of rapid, motion-immune sequences now makes MR imaging a feasible study in less cooperative patients extending the range of patients for whom a diagnostic study can be achieved. Capitalizing on the unique benefits of MR imaging there is optimism that MR imaging can eliminate test redundancy and impact patient care in a cost-effective manner. Further investigations are needed to identify the diagnostic algorithms for which this favorable use holds true.

Abdomen, Acute↗
PubMed2003

Coronary MR angiography clinical applications and potential for imaging coronary artery disease.

Over the past decade, CMRA has emerged as a unique clinical imaging tool with applications in selected populations. Patients with suspected coronary artery anomalies and patients with Kawasaki disease and coronary aneurysms are among those for whom CMRA has demonstrated clinical usefulness. For assessment of patients with atherosclerotic CAD, CMRA is useful for detection of patency of bypass grafts. At centers with appropriate expertise and resources, CMRA also appears to be of value for exclusion of severe proximal multivessel CAD in selected patients. Data from multicenter trials will continue to define the clinical role of CMRA, particularly as it relates to assessment of CAD. Future developments and enhancements of CMRA promise better lumen and coronary artery wall imaging. This may become the new target in noninvasive evaluation of CAD.

Coronary Disease↗
PubMed2003

Determinations of prostate volume at 3-Tesla using an external phased array coil: comparison to pathologic specimens.

RATIONALE AND OBJECTIVES: To compare techniques for measuring in vivo prostate volumes using torso phased-array imaging at 3-Tesla. METHODS: Eleven patients imaged at 3-Tesla with a torso-phased array coil using multiplanar fast spin echo (FSE) T2-weighted imaging who underwent radical prostatectomy comprised the study population. Surgical specimens were imaged. The pathologic specimen volume was compared with varieties of magnetic resonance volume determinations, the latter using ellipsoid and planimetric assessments. Three-dimensional images of the excised prostate were generated. Linear correlation coefficients were calculated comparing volume determinations from image data and pathologic data. RESULTS: Correlation coefficient (r2) values from the ellipsoid formula among six different data sets ranging between 0.325 to 0.751; the highest in vivo r2 value was obtained by multiplying the anterior-posterior and the superior-inferior dimensions from the sagittal image by the right-left dimension from the axial image. The r2 values of the planimetric volume and specimen 3-dimensional volume rendering were 0.652 and 0.86, respectively. CONCLUSIONS: Surface coil prostate imaging at 3-Tesla provides undistorted images for volume assessment and in vivo volume determinations very close to ex vivo imaging volume determinations.

Adenocarcinoma↗
PubMed2003

The role of magnetic resonance imaging in the management of vascular malformations of the trunk and extremities.

Vascular malformations can usually be diagnosed on clinical grounds. They have a well-defined appearance on magnetic resonance imaging, which can effectively determine their tissue and flow characteristics. However, the role of cross-sectional imaging in the management of vascular malformations is not well defined. Most reviews suggest that magnetic resonance imaging should be reserved for cases in which the extent of the lesion cannot be estimated on physical examination. However, to date no group has compared the accuracy of physical examination alone to that of magnetic resonance imaging in determining this extent. A review was performed of all the patients evaluated for vascular malformations at the New York University Trunk and Extremity Vascular Anomalies Conference between July of 1994 and August of 1999. Patients who underwent magnetic resonance evaluation at other institutions and whose images were not available for review were excluded. All study patients either underwent magnetic resonance imaging examination at New York University Medical Center or had outside films reviewed at the center. The physical examination findings were compared with the magnetic resonance findings and the surgeon and radiologist made a joint decision about whether there was a correlation between the magnetic resonance and physical examination findings. Fifty-eight patients met the study criteria, 44 (76 percent) of whom were found to have more extensive disease on magnetic resonance examination than appreciated on physical examination. Of the 51 patients with low-flow vascular malformations (venous vascular malformations, lymphatic malformations, and capillary malformations), 39 (76 percent) had more extensive disease on magnetic resonance examination than on physical examination. Of the seven patients with high-flow arteriovenous malformations, five had more extensive disease on magnetic resonance. In all of the 44 patients whose magnetic resonance imaging findings did not correlate with those of the physical examination, therapeutic decision making was affected. Contrary to the conventional wisdom of published reviews, physical examination findings significantly underestimated the extent of vascular malformations in the majority of cases. Magnetic resonance imaging should be performed in all patients with vascular malformations of the trunk and extremities before therapy is planned. In an age when physicians are asked to justify their decisions, especially where the use of expensive diagnostic modalities is concerned, the situations in which these tests are indispensable must be clearly defined or else patients will be denied access to them.

Adolescent↗
PubMed2002

Effort-induced thrombosis: diagnosis with three-dimensional MR venography.

A case of Paget-von Schrötter syndrome diagnosed with gadolinium-enhanced magnetic resonance (MR) venography is described. MR enabled a comprehensive evaluation with identification of the thrombus within the left subclavian vein and a hypertrophied anterior scalene muscle as the probable cause of the patient's condition. We describe the MR venography technique used for evaluation of the subclavian vein and the imaging findings in this entity.

Journal Article↗
PubMed2002

Magnetic resonance imaging of arterioportal shunts in the liver.

Localized perfusional variations are being seen more frequently in magnetic resonance imaging (MRI) as the increased reliance of the optimized arterial-phase contrast-enhanced strategies has become more commonplace. Many of these findings are related to the various organic or functional arterioportal shunts in the liver. The associated alterations in physiologic flow, decreased or absent portal venous flow, and increased arterial flow result in a regional display of high signal intensity on arterial-phase dominant contrast-enhanced MRI. For accurate diagnosis and planning of patient management, the etiology of the shunt should be distinguished as tumor related or not, and it may need to be differentiated from a hypervascular tumor. Depending on the chronicity of diminished portal flow, substantial parenchymal changes may ensue, including focal fat sparing or the finding of functional infarct, either of which can be demonstrated on static MRI. This article reviews and illustrates the MRI findings of localized tumor-related and nontumorous arterioportal shunts in the liver.

Adult↗