Magnetic resonance imaging of the prostate.
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Humans↗
Biomedical subjects
M D Schnall
Publications and source records attributed to M D Schnall.
MR angiography of the peripheral vasculature.
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Artifacts↗
Characterization of hemorrhagic adnexal lesions with MR imaging: blinded reader study.
To assess the performance of published criteria for differentiation of endometriomas from other hemorrhagic adnexal lesions with magnetic resonance (MR) imaging, 74 lesions with pathologic proof in 46 patients were evaluated by means of a 1.5-T system with use of conventional T1-weighted and either T2-weighted spin-echo (SE) or fast SE sequences. The MR images were independently presented to each of three blinded readers, and receiver operating characteristic (ROC) curve analysis was performed. The criterion of a cyst with high signal intensity on short repetition time (TR)/echo time (TE) images and shading on long TR/TE images had a mean sensitivity of 68%, mean specificity of 83%, and mean accuracy of 76% for diagnosis of endometrioma. Ancillary findings previously reported to be suggestive of endometrioma (eg, low-signal-intensity rims, adhesions, bowel tethering, and implants) were proved inaccurate and showed low interobserver agreement. ROC analysis showed similar area measurements among the three radiologists for diagnosis of endometrioma. MR imaging had only moderate accuracy in distinction of endometriomas from other hemorrhagic adnexal lesions.
Adnexal Diseases↗
Proton MR spectroscopy of HIV-infected patients: characterization of abnormalities with imaging and clinical correlation.
The purpose of this study was to characterize the proton magnetic resonance (MR) spectroscopic findings in the brains of patients infected with human immunodeficiency virus (HIV). Peak areas were used to calculate metabolite ratios. Spectra were analyzed by blinded readers who calculated areas under metabolite peaks. MR images were evaluated by blinded readers, with both white and gray matter being rated as normal or abnormal. An aggregate index that combined N-acetylaspartate/creatine (Cr), choline/Cr, and marker peak/Cr ratios resulted in mean scores for patients and control subjects of 4.4 +/- 1.5 (standard deviation [SD]) and 2.5 +/- 0.4, respectively (P = .001). Eight of 11 patients (73%) had abnormal MR images versus four of 11 control subjects. Thirteen of 15 patient spectra (87%) were abnormal (> 2 SDs from the mean of the control subjects), while only one of 10 control spectra was abnormal. These initial results indicate that proton MR spectroscopy is a potentially useful modality for detecting HIV involvement in the central nervous system.
AIDS Dementia Complex↗
Current role of MR imaging in the staging of adenocarcinoma of the prostate.
Surgical cure of adenocarcinoma of the prostate (ACP) is possible in over 80% of cases when the disease is confined to the gland capsule. The endorectal probe for magnetic resonance (MR) imaging has increased resolution of the prostate gland and capsule, which has improved the sensitivity and specificity for staging ACP (.65 sensitivity, .69 specificity for body coil; .87 sensitivity, .85 specificity for the endorectal coil). Normal glandular regions in the peripheral zone and central zone have significantly higher citrate levels than ACP and fibromuscular and fibrous benign prostatic hyperplasia at proton spectroscopy. ACP has a higher phosphomonoester-phosphocreatine ratio than normal glandular tissue at phosphorus spectroscopy. The combination of endorectal coil MR imaging for local spread, and body coil MR imaging for advanced disease, makes MR imaging the premier imaging modality for the preoperative staging of ACP.
Adenocarcinoma↗
Senile amyloidosis of the seminal vesicles mimicking metastatic spread of prostatic carcinoma on MR images.
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Aged↗
Magnetic resonance arteriography of the pelvis and lower extremities.
Reconstructive vascular surgery is the last resort for limb salvage in patients with vascular insufficiency. Planning the sites of arterial bypass grafts depends on an exact knowledge of the angiographic anatomy. Currently, conventional contrast angiography is the primary preoperative study for surgical planning. Recently, magnetic resonance (MR) arteriography has been shown to be an accurate technique for the evaluation of slow arterial flow in the lower extremities. The purpose of this review will be to show how MR arteriography can be used as both an adjunct to and in some cases instead of conventional angiography for the preoperative assessment of lower-extremity vascular reconstruction. The derivation of common artifacts, the many pitfalls of interpretation, and the evaluation of peripheral arterial occlusion and percentage stenosis will be discussed. MR arteriography of the lower extremities is an important advance for the noninvasive evaluation of disease of the peripheral vasculature.
Algorithms↗
Magnetic resonance imaging in carcinoma of the prostate.
Over the past few years, magnetic resonance imaging (MRI) has been shown to be of great value in imaging the pelvis. Its advantages derive from its multiplanar capability and high soft-tissue contrast, which are particularly significant in imaging the prostate and seminal vesicles. MRI, particularly with endorectal surface coils, provides excellent visualization of the prostate and periprostatic anatomy in multiple planes. It is also useful in evaluating the remainder of the pelvis, including lymph nodes and the bony pelvis. This makes MRI the most reliable noninvasive staging modality for prostate cancer.
Humans↗
Experimental allergic encephalomyelitis and multiple sclerosis: lesion characterization with magnetization transfer imaging.
Magnetization transfer imaging (MTI) was initially performed in normal guinea pigs and human volunteers. A magnetization transfer ratio (MTR) was calculated in the normal white matter and was found to be 42%-44%, with less than 2.5% variation, which indicates the high reproducibility of the measurement. MTI was then applied to an animal model of white matter disease, acute experimental allergic encephalomyelitis (EAE). In this model of EAE, pathologically proved lesions were edematous with essentially no demyelination. MTRs decreased slightly but significantly (5%-8%) compared with the MTRs of the same tissue region measured before the onset of the lesion [corrected]. Fifteen patients with multiple sclerosis (MS) also underwent MTI. In the 15 patients with MS, all lesions (209 plaques) had a significantly decreased MTR (average, 26%). The authors believe that demyelination produced the lower MTR, and, thus, lesions varied in transfer ratio on the basis of the extent of myelin loss. In patients with MS, particularly those with chronic and/or progressive MS, the MTR of the normal-appearing white matter was significantly decreased. The data suggest that calculated MTR obtained with in vivo MTI may enable differentiation of edema from demyelination, and that MTI can demonstrate white matter abnormalities that cannot be seen with standard spin-echo or gradient-echo magnetic resonance imaging.
Adult↗
Magnetization transfer of hepatic lesions: evaluation of a novel contrast technique in the abdomen.
The authors evaluated the technique of magnetization transfer to determine if it could enable distinction of benign from malignant liver lesions. Thirteen patients with 27 hemangiomas or cysts and 13 patients with 31 malignant liver lesions underwent magnetic resonance imaging. Hepatic malignancies demonstrated magnetization transfer similar to that of the liver. However, hemangiomas and cysts showed significantly less magnetization transfer than malignant liver lesions. Gradient-recalled-echo imaging with the off-resonance saturation pulse showed increased lesion contrast compared with the liver for hemangiomas and cysts but not for malignancies. On the basis of signal intensity measurements alone (ie, ignoring morphologic criteria), the magnetization transfer studies showed an area under the receiver operating characteristic curve of 0.96 for distinguishing benign from malignant liver lesions. Though the separation of these two groups was imperfect, it was comparable with that achieved with qualitative analysis of signal intensity ratios at spin-echo imaging.
Cysts↗
The seminal tract in patients with ejaculatory dysfunction: MR imaging with an endorectal surface coil.
Twenty-six patients with signs and symptoms of ejaculatory dysfunction (hemospermia, hypospermia, oligospermia, or painful ejaculation) were examined with high-resolution MR imaging with an endorectal surface coil. Findings were abnormal in 15 patients. Abnormalities detected included four cases of müllerian cysts, three cases of wolffian cysts, one case of anaplastic prostatic carcinoma, and various noncystic abnormalities of the seminal vesicles and ejaculatory ducts, including ejaculatory duct obstruction and seminal vesiculitis. In all cases, depiction of both the normal and abnormal anatomy of the entire seminal tract, including the vas deferens, seminal vesicles, and ejaculatory ducts, was excellent. This depiction of the detailed anatomy of the prostatic cysts made it possible to suggest specific diagnoses. Our results show the value of MR imaging with an endorectal surface coil in the examination of patients with ejaculatory dysfunction.
Adolescent↗
Prostate cancer: local staging with endorectal surface coil MR imaging.
Endorectal surface coil magnetic resonance (MR) imaging was used to stage the local extent of prostate cancer in 22 patients. The endorectal coil images were acquired with a 10-12-cm field of view and a 4-mm section thickness. All pathologic specimens were reviewed by one pathologist. Endorectal surface coil MR imaging was 82% accurate in the differentiation of stage B from stage C cancer. One case was overestimated, and three cases were underestimated. The three underestimated cases consisted of two cases of microscopic capsular invasion and one case of minimal seminal vesicle invasion. In a comparison of retrospective, blinded readings of endorectal coil and body coil images, there was an average improvement in accuracy of 16% in staging prostate cancer with endorectal coil images.
Carcinoma↗
Cervical carcinoma: MR imaging with an endorectal surface coil.
Ten consecutive patients with biopsy-proved invasive cervical carcinoma underwent magnetic resonance (MR) imaging with both a standard body coil and with an endorectal surface coil. The endorectal coil provided a markedly improved signal-to-noise ratio, enabling the use of small fields of view; thus, the images had significantly improved in-plane resolution. The images were assigned an MR imaging stage based on the clinical staging system of the International Federation of Gynecology and Obstetrics. Vaginal wall, vaginal fornix, parametrium, and pelvic side-wall invasion by tumor were all well demonstrated. When compared with body coil images, the endorectal coil images provided increased anatomic detail and demonstrated tissue planes between tumor and normal structures that were not seen on the body coil images. This preliminary investigation indicates that use of an endorectal surface coil is a promising technique to obtain high-resolution images of the female genital tract. This technique has the potential to improve the accuracy of staging for cervical carcinoma.
Adult↗
Magnetic resonance imaging of the prostate gland.
MRI, because of its multiplaner capability and high soft tissue contrast, is ideally suited for examination of the prostate. The normal prostatic zonal architecture and periprostatic anatomy can be visualized. The use of an endorectal surface coil greatly enhances resolution. Clinical application to the study of BPH, prostate carcinoma, prostatic cysts, and inflammatory disease is discussed. MRI appears to be emerging as the modality of choice for imaging the prostate.
Adenocarcinoma↗
Colorectal tumors: an in vitro study of high-resolution MR imaging.
To study the potential utility of magnetic resonance (MR) imaging in staging colorectal tumors, 15 resected colonic segments containing 17 elevated lesions were examined on a 1.5- or 1.9-T superconductive MR system. The whole intestinal wall was apparent as three or five layers on images obtained with a short repetition time (TR) and short echo time (TE) and as six or eight distinct layers, including the intestinal wall proper as well as an adherent mucus layer and an outer layer of pericolonic fat, on the long TR/TE images. In cases of colonic carcinoma, MR images correlated well with the pathologic findings, including the macroscopic growth pattern, depth of mural invasion, and the presence of foci of calcific tumor necrosis and pools of extracellular mucin (colloid). These features suggest that MR imaging may be valuable in the clinical evaluation of colorectal tumors.
Adenocarcinoma↗
Magnetic resonance imaging of the prostate.
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Humans↗
Prostate: MR imaging with an endorectal surface coil.
An endorectal surface coil has been developed to obtain high-resolution magnetic resonance images of the prostate. The probe consists of a surface coil mounted on the inner surface of a balloon. The balloon is concave to ensure tight seating against the prostate. The coil has been used in 15 patients with biopsy-proved prostatic carcinoma and in two healthy volunteers. The axial images were obtained with a 12-16-cm field of view and a 3-mm section thickness. Compared with images obtained with a body coil, the surface coil images better demonstrate prostatic anatomy and pathologic conditions.
Humans↗
Chronic wrist pain: evaluation with high-resolution MR imaging.
The diagnostic performance of magnetic resonance (MR) imaging in the evaluation of the triangular fibrocartilage complex and the intrinsic and extrinsic ligaments of the wrist was assessed in 43 patients with chronic wrist pain. Forty-one patients underwent correlative arthrography. Twenty-three patients underwent arthroscopy or arthrotomy or both. The normal anatomy of the triangular fibrocartilage and the intrinsic and extrinsic ligaments could be demonstrated effectively with MR imaging. MR imaging was effective in the evaluation of triangular fibrocartilage tears with a sensitivity of 1.0, a specificity of 0.93, and an accuracy of 0.95 when compared with arthrography; 0.89, 0.92, and 0.90, respectively, when compared with arthroscopy and arthrotomy. MR imaging could also be used effectively to evaluate tears of the intercarpal ligaments, particularly the scapholunate ligament. Disruptions of the extrinsic ligaments, articular cartilage defects, and subluxations of the distal radioulnar joint were also well demonstrated. MR imaging is an effective procedure in assessing patients with chronic wrist pain.
Cartilage, Articular↗