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Biomedical subjects

H Hricak

Publications and source records attributed to H Hricak.

At least 91 records · Page 5Linked to original sources
PubMed1996

Abdominopelvic MR imaging in the nonobstetric evaluation of pregnant patients.

Managing a pregnant patient with a suspected nonobstetric abdominopelvic disorder is challenging. Information from imaging affects the treatment options, which range from operating emergently and risking miscarriage to terminating the pregnancy or delaying treatment until after delivery. The most common indications for MR imaging during pregnancy are disorders of the central nervous and cardiovascular systems. In the evaluation of the abdomen and pelvis, sonography plays the pivotal role; however, sonography may be inconclusive because of its limited specificity in tissue characterization and technical difficulties caused by the enlarged uterus. For these reasons MR imaging has emerged as a valuable adjunct to sonography. In this pictorial essay we describe a variety of nonobstetric abdominopelvic disorders during pregnancy in which MR imaging contributed to patient management.

Abdomen↗
PubMed1996

Hormonal ablation of prostatic cancer: effects on prostate morphology, tumor detection, and staging by endorectal coil MR imaging.

OBJECTIVE: The purpose of our study was to evaluate the effect of androgen deprivation therapy on the MR imaging findings of prostate gland anatomy and cancer pathology in men with prostatic cancer treated with hormonal ablation before radical prostatectomy. MATERIALS AND METHODS: Twenty-two patients (mean age, 66 years old) were divided into two groups: in group I (n=10), MR imaging studies were done before and after hormonal treatment; in group II (n=12), MR imaging studies were done only after hormonal treatment. MR imaging was performed on a 1.5 T-scanner (Signa; General Electric Medical Systems, Milwaukee, WI) and included transverse plane phased-array coil T1-weighted images (TR/TE, 600/12), combined endorectal phased-array coil transverse plane T1-weighted images, fast spin-echo T2-weighted (4000/102), and coronal plane fast spin-echo T2-weighted images. Image evaluation was by consensus and included assessment of the gland size, signal intensity, tumor depiction, extracapsular extension, seminal vesicle invasion, and overall staging accuracy (Jewett and Whitmore classification). MR imaging findings were correlated with pathologic findings of step section radical prostatectomy. RESULTS: After hormonal therapy, the volume of the prostate gland showed a mean decrease of 33.5% +/- 19.6% SD (range, 0-64%). Volume reduction in the transition zone (mean 29.2% +/- 22% SD) was less than in the peripheral zone (mean, 55.8% +/- 25.8% SD) (p < .05). On T2-weighted images, the peripheral zone showed homogeneous decreases in signal intensity in 13 of 22 (58%) patients. Compared with pathologic findings, the accuracy of tumor detection by MR imaging was 74% (98 of 132 sites). Tumor presence was overestimated in 32 of 132 (24%) sites. Overall staging accuracy after hormonal ablation was 68% (15 of 22). The positive predictive value and negative predictive value for extracapsular extension were 57% (13 of 23 sites) and 90% (19 of 21 sites), respectively, and for seminal vesicle invasion were 80% (8 of 10 sites) and 97% (33 of 34 sites), respectively. CONCLUSION: As detected by MR imaging, hormonal ablation caused a decrease in size and signal intensity of the prostate gland and seminal vesicles and overestimation of tumor presence and extracapsular extension.

Aged↗
PubMed1996

MR imaging of the female pelvis.

MR imaging has proved to be an extremely powerful tool for the evaluation of the female pelvis. Improved imaging techniques and widespread availability of MR imaging have made the routine acquisition of high-quality images possible. MR imaging has a well-documented use for the diagnosis and staging of pelvic malignancies. Recent efforts have also demonstrated the usefulness of MR imaging as an adjunct to sonography or as the primary imaging modality for the diagnosis and characterization of benign diseases of the pelvis.

Female↗
PubMed1995

Cervical carcinoma: computed tomography and magnetic resonance imaging for preoperative staging.

OBJECTIVE: To assess the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) in the evaluation of invasive cervical cancer. METHODS: Seventy-nine women with untreated cervical cancer underwent pre-treatment MRI (n = 71) and/or CT (n = 37) within 4 weeks of surgical evaluation. Twenty-nine women had both MRI and CT. Images were evaluated for tumor detection, size, stromal invasion, local extension, and nodal metastases. RESULTS: Tumor size was evaluated accurately by MRI, with a correlation coefficient of 0.93. Magnetic resonance estimates of tumor size were within 0.5 cm of the surgical sample in 64 of 69 women (93%). Magnetic resonance was 88% accurate evaluating the presence of stromal invasion and 78% accurate for depth of stromal invasion. Computed tomography could not evaluate tumor size or stromal invasion because it could not distinguish cancer from the surrounding normal cervical tissue. In evaluating stage of disease, MRI had an accuracy of 90%, compared with 65% for CT (P < .005). Magnetic resonance imaging was more accurate than CT (94 versus 76%, P < .005) in assessing parametrial invasion. Both modalities were comparable in evaluating lymph node metastases (86% each). In determining operative candidates (stage I and minimal IIA), MRI was 94% accurate, compared with 76% for CT (P < .005). CONCLUSION: Compared with CT, MRI offered significantly improved evaluation of tumor size, stromal invasion, and local and regional extent of disease in pre-treatment imaging for cervical cancer.

Adult↗
PubMed1995

Citrate as an in vivo marker to discriminate prostate cancer from benign prostatic hyperplasia and normal prostate peripheral zone: detection via localized proton spectroscopy.

OBJECTIVES: This study was designed to determine whether citrate levels detected by localized 1H spectroscopy could reliably discriminate regions of prostate adenocarcinoma from surrounding regions of normal peripheral zone and benign prostatic hyperplasia (BPH). METHODS: In 28 patients and 5 volunteers stimulated echo proton spectroscopy was used in conjunction with endorectal surface coils to obtain water-suppressed 1H spectra from regions of normal prostate peripheral zone, BPH, and prostate cancer. 1H spectra from prostate cancer patients were correlated with pathologic areas identified on T2-weighted endorectal coil magnetic resonance (MR) images and histologic study of the step-sectioned gland after surgery. RESULTS: The major finding of in vivo studies was consistently lower citrate levels in prostate cancer compared with BPH and normal prostate peripheral zone. This was reflected by significantly (P < 0.05) lower mean citrate/(creatine plus choline) peak area ratio observed for regions of cancer (0.67 +/- 0.17) compared with BPH (1.21 +/- 0.29) and normal peripheral zone (1.46 +/- 0.28). Moreover, there was no overlap of individual cancer and normal peripheral zone citrate ratios and no significant difference between citrate ratios in regions of normal peripheral zone in young volunteers (1.28 +/- 0.14) and age-matched patients (1.46 +/- 0.28). The observed alterations in vivo citrate levels were supported by citrate concentration data obtained from extracts of histologically proven samples of normal, benign, and malignant prostatic tissues removed at surgery. In vitro citrate levels in the normal peripheral zone (30.9 +/- 8.5 mumol/g wet weight) and BPH (46.3 +/- 5.4 mumol/g wet weight) were significantly higher than those for prostate cancer (3.74 +/- 0.54 mumol/g wet weight). CONCLUSIONS: These studies further demonstrate the potential of citrate as an in vivo marker for discriminating prostate cancer from surrounding regions of normal peripheral zone and BPH.

Adenocarcinoma↗
PubMed1995

Magnetic resonance imaging of vascular lesions of the scrotum and penis.

We report 2 rare cases of vascular lesions in the scrotum and penis: an arteriovenous malformation in a young man and a lymphohemangioma in a boy. Both patients had undergone previous treatment and had recurrent lesions. Magnetic resonance imaging was performed preoperatively for detailed information regarding lesion extent and involvement of adjacent structures.

Adolescent↗
PubMed1995

Radiation-induced decrease in nitric oxide synthase--containing nerves in the rat penis.

PURPOSE: Evaluate effect of prostatic irradiation on erectile function. MATERIALS AND METHODS: Forty-seven male adult rats were divided into three groups according to a single radiation dose to the prostate: control (no irradiation) (n = 15), 1,000 cGy (n = 15), and 2,000 cGy (n = 17). Five months after irradiation, rats underwent evaluation of penile vascularity and of erectile response to central and peripheral stimulation. After the study a proximal-shaft penile segment was obtained for staining. RESULTS: Histologic evaluation demonstrated that, with increasing radiation, the number of nitric oxide synthase-containing nerve fibers per penile segment decreased significantly: control, 225.6 +/- 9.7; 1,000 cGy, 156.3 +/- 12.0; 2,000 cGy, 85.8 +/- 10.1 (standard error of the mean). Maximal intracavernous pressure induced with electrostimulation decreased significantly with increasing radiation dose. After injection of papaverine, maximal intracavernous pressure was significantly decreased in only the 2,000-cGy group. CONCLUSION: A dose of 2,000 cGy over the prostatic bed induces erectile dysfunction by causing defects in the vascular supply of the erectile tissue and in the nerves and smooth muscle.

Amino Acid Oxidoreductases↗
PubMed1995

Prostate cancer: effect of postbiopsy hemorrhage on interpretation of MR images.

PURPOSE: To assess the frequency of changes in signal intensity after prostatic biopsy and the effect of these changes on the magnetic resonance (MR) imaging staging of prostate cancer. MATERIALS AND METHODS: Seventy-three patients with biopsy-proved prostate cancer were divided into two groups according to time between biopsy and imaging (less than and more than 21 days). The findings at MR imaging were compared with those at pathologic examination. RESULTS: Postbiopsy hemorrhage was detected in 21 of 26 (81%) patients who underwent imaging less than 21 days after biopsy and in 23 of 47 (49%) patients who underwent imaging more than 21 days after biopsy (P < .01). Postbiopsy changes persisted for as long as 4 1/2 months. Less than 21 days after biopsy, there was a tendency to overestimate tumor presence and extracapsular extension. After 21 days, tumor presence was underestimated but the positive predictive value for extracapsular extension was improved. Staging accuracy less than 21 days after biopsy was 46%; this improved to 83% after 21 days (P < .01). CONCLUSION: Staging accuracy is significantly improved when imaging is deferred for 21 days after biopsy.

Biopsy, Needle↗
PubMed1995

Ovarian cancer recurrence: value of MR imaging.

PURPOSE: To assess magnetic resonance (MR) imaging in depiction of ovarian tumor recurrence and for identification of patients who may not benefit from surgical reexploration. MATERIALS AND METHODS: In a prospective study, 34 patients (mean age, 57.07 years) with surgically staged ovarian cancer underwent MR imaging before reexploration. Findings at MR imaging and surgery were correlated. MR imaging tumor depiction was correlated with tumor size, presence of ascites, and CA-125 levels. RESULTS: Tumor recurrence was identified in 29 patients at surgery. MR imaging depicted tumor in 20 patients. Accuracy for lesions smaller than 2 cm was 35% and increased to 82% for lesions larger than 2 cm (P < .01). MR imaging had low sensitivity for depiction of implants in the peritoneum and mesentery. Ascites improved depiction of smaller lesions (< 2 cm). MR imaging in combination with CA-125 levels improved detection of recurrent disease (CA-125 measurement alone 53% vs CA-125 measurement and MR imaging 75%, P = .048). CONCLUSION: MR imaging is a useful adjunct to the clinical examination to identify patients with recurrent disease and those in whom reexploration may not be beneficial.

Adult↗
PubMed1995

Ovarian cancer: staging with CT and MR imaging.

PURPOSE: To evaluate ovarian cancer staging and tumor resectability with computed tomography (CT) or magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eighty-two women underwent CT (n = 43) or MR imaging (n = 50); eleven of these 82 underwent both. Imaging was performed within 4 weeks of surgical staging. Radiologic, surgical, and histopathologic findings were compared. RESULTS: Overall staging accuracy was similar for CT and MR imaging (77% [33 of 43] vs 78% [39 of 50]). Evaluation of pelvic cancer extent was better with MR imaging than with CT. There was no difference in detection of abdominal disease. Most mesenteric and small-bowel implants were not detected with either CT or MR imaging. For CT, the positive predictive value for cancer nonresectability was 100% (three of three patients); the negative predictive value was 92% (37 of 40 patients). The positive and negative predictive values for MR imaging were 91% (10 of 11 patients) and 97% (38 of 39 patients). CONCLUSION: While the staging accuracy of both CT and MR imaging is only moderate, prediction of tumor resectability is excellent.

Abdominal Neoplasms↗
PubMed1995

The use and accuracy of cross-sectional imaging and fine needle aspiration cytology for detection of pelvic lymph node metastases before radical prostatectomy.

The role of cross-sectional pelvic imaging with computerized tomography or magnetic resonance imaging and fine needle aspiration in the assessment of pelvic lymph nodes in patients with prostate cancer is undefined. To address this issue we used formal decision analysis, comparing an imaging arm to a no imaging arm. Patient utility values were calculated, and test parameters and complication rates were extracted from the literature. Imaging was superior to no imaging only when the pretest probability of pelvic lymph node metastases was high. The most important parameter was the sensitivity of cross-sectional imaging for lymphadenopathy. When the sensitivity was 36%, which was the baseline figure derived from the literature, the probability of lymph node metastases required for imaging to be beneficial overall was 32%. We also performed a retrospective review of magnetic resonance imaging examinations at our institution in 174 patients with newly diagnosed prostate cancer and pathological confirmation of nodal status. The sensitivity for detecting nodal metastases was 25%. With this figure, the estimated probability of nodal metastases required to make imaging beneficial would be 45%, which is possible to achieve with highly selective clinical criteria. With a policy of imaging only in select patients the marginal cost is $794 per patient benefited (aborted radical prostatectomy because of nodal metastases detected with fine needle aspiration) compared to $50,661 per patient benefited if all patients are imaged. Thus, cross-sectional pelvic imaging before radical prostatectomy, solely for the purpose of detecting pelvic lymph node metastases, is not justified routinely. However, it is worthwhile on the basis of patient use values and cost-effectiveness in a select group of patients at high risk for nodal metastases.

Biopsy, Needle↗
PubMed1994

Role of MRI in the evaluation of ambiguous genitalia.

Diagnostic accuracy of magnetic resonance imaging (MRI) interpretation was assessed prospectively in patients with ambiguous genitalia or intersex problems. MRI depiction of the uterus was possible in 93%, the vagina in 95%, the penis in 100%, the testis in 88%, and the ovary in 74% of patients. The strength of MRI lies in the multiplanar capability and tissue characterization by means of T1- and T2-weighted sequences. MRI contributes to accurate morphologic evaluation of müllerian duct structures, the gonads, and the development of the phallus, all of which are essential for appropriate gender assignment and planning of surgical reconstruction.

Adolescent↗