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Biomedical subjects

H Hricak

Publications and source records attributed to H Hricak.

At least 19 recordsLinked to original sources
PubMed1992

Bile duct disease: prospective comparison of ERCP, CT, and fat suppression MRI.

The authors compared computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP), techniques commonly used to study the biliary tree, with pre- and post-Gd-DTPA breath-hold fast low angle shot (FLASH) and fat suppressed spin-echo in 28 consecutive patients with bile duct abnormalities detected on ERCP, including 11 patients with malignant disease and 17 patients with benign disease. ERCP, CT, and magnetic resonance (MR) images were prospectively interpreted in a blinded fashion and reviewed by consensus. ERCP characterized all cases of malignant disease by the presence of a narrowed bile duct lumen with irregular margins. CT and MRI detected all cases of malignant disease and characterized nine of 11 as malignant. In seven of these cases, CT and MRI showed thickening of extrahepatic bile duct walls greater than 5 mm. MRI images showed intrahepatic-enhancing periportal tissue in four cases, which was not seen on CT images, and which was biopsy-proven tumor extension. Benign disease was characterized on ERCP images by the demonstration of smooth tapered narrowings in 16 cases, whereas on CT and MR images it was characterized by mild to moderate dilatation of the intrahepatic bile ducts and wall thickness less than 5 mm in 13 cases. Overall ERCP correctly characterized 27 cases as benign or malignant and CT and MRI both characterized 25. The results of this study show a trend that ERCP is superior to CT and MRI for characterizing bile duct disease.

Adult↗
PubMed1992

Magnetic resonance imaging of traumatic posterior urethral defects and pelvic crush injuries.

A total of 18 patients 4 to 71 years old with complete occlusion of the prostatomembranous urethra from pelvic crush injury underwent magnetic resonance imaging (MRI) of the pelvis just before open urethroplasty. MRI studies included T2-weighted sagittal and coronal images as well as transaxial T1 and T2-weighted spin-echo images. Operative findings and erectile function were correlated with MRI findings. All patients underwent conventional cystography and retrograde urethrography. The mean interval from injury to operation was 5.5 months (range 3 to 12 months) and followup averaged 12 months (range 3 to 40 months). Posttraumatic pelvic anatomy can be distorted and imaging in all 3 planes was needed. The severity and direction of prostatourethral dislocation, and the length of the urethral defect could be accurately determined, which often is not possible with conventional radiographic studies. MRI also demonstrated injuries at many locations along the erectile pathway, including sacral and ischial fractures as well as fractures and avulsions of the cavernous bodies. Pelvic MRI can accurately define the pelvic anatomy after crush injury and, therefore, it can provide useful preoperative information that cannot be obtained by conventional radiographic studies. Our results correlating MRI findings of cavernous avulsion with clinical impotence require further study.

Adolescent↗
PubMed1992

Detection and staging of prostatic carcinoma after transurethral resection or open enucleation of the prostate: accuracy of magnetic resonance imaging.

A total of 17 patients who had undergone transurethral (16) or open (1) enucleation of the prostate for presumed benign prostatic hyperplasia had prostatic adenocarcinoma: 10 on the basis of examination of the resected specimen (stage A) and 7 upon rectal examination performed 2 to 120 months after prostatectomy for benign prostatic hyperplasia (stage B). In all patients magnetic resonance imaging (MRI) of the prostate was performed before radical retropubic prostatectomy. Preoperative imaging was compared to pathological findings with respect to the presence, location and stage of singular or multiple prostatic carcinomas. Carcinomas were categorized according to the location within the prostate: whether on the right or left side, and whether in the peripheral zone (anterior, anterolateral or posterior) or the transition zone. The sensitivity of tumor detection for cancers originating in the peripheral zone was 81%. However, the sensitivity of detection decreased to 0% for tumors confined to the transition zone. Tumor staging was not compromised by previous prostatic enucleation or transurethral resection. MRI correctly identifies carcinomas originating in the peripheral zone but cannot detect those confined to the transition zone.

Adenocarcinoma↗
PubMed1992

The effect of magnetic resonance imagers on implanted neurostimulators.

This in-vitro study was designed to investigate the safety of various implanted neurostimulators in magnetic resonance (MR) imagers. The effects of the static and changing magnetic fields and the radio frequency (RF) electromagnetic field generated by 0.35 and 1.5 T MR imagers on the voltage output of four models of implantable passive neurostimulators and two models of implantable self-powered neurostimulators was studied. The neurostimulators were mounted on a support and placed in the imagers. An oscilloscope monitored the voltages at the outputs of the neurostimulators. For an Avery single-channel stimulator, located at the isocenter, the amplitude of the output pulses induced by the 0.35 T imager was 6V; from a 1.5 T imager, it was 12 V. These amplitudes can cause discomfort and possible harm to a patient if the typical therapeutic value is 1-5 V. The amplitude of the stimulator receiver's output decreased to relatively safe values beyond 40 cm from the isocenter. By contrast, there was no significant voltage output from the Medtronic SE-4 receiver. For two models of self-powered neurostimulators, the Medtronic Itrel and the Cordis MK II, the programmed stimulus parameters were not affected by the pulsed magnetic fields of the MR imagers. However, the RF fields at the isocenter heated the metal case of the stimulators. The rotational and linear forces produced by the fixed magnet on the Cordis MK II were judged to be too strong for a patient with this implant to be scanned. The study showed that patients with certain types of implanted neurostimulators can be scanned safely under certain conditions.

Electric Stimulation Therapy↗
PubMed1992

MR imaging in the evaluation of benign uterine masses: value of gadopentetate dimeglumine-enhanced T1-weighted images.

Forty-six patients with surgically proved disease (115 leiomyomas, 19 cases of adenomyosis, and 14 endometrial polyps) were studied to determine if gadopentetate dimeglumine-enhanced T1-weighted MR images improve the detection and characterization of benign tumors of the uterus. Lesion detection and characterization were assessed separately for each sequence (unenhanced T1-weighted, proton-density-weighted, and T2-weighted and contrast-enhanced T1-weighted images) and for combinations of sequences (unenhanced T1- and T2-weighted images, unenhanced and contrast-enhanced T1-weighted images, and unenhanced T1- and T2-weighted and contrast-enhanced T1-weighted images). In the evaluation of leiomyomas, analysis of all three sequences provided the best detection (92%) and characterization (92%), but the improvement, except when compared with unenhanced T1-weighted images alone, was not statistically significant. The use of contrast medium did not contribute to either tumor detection or characterization. In the evaluation of adenomyosis, T2-weighted images provided significantly better lesion detection and characterization than did either unenhanced or contrast-enhanced T1-weighted images. In the evaluation of endometrial polyps, however, contrast-enhanced T1-weighted images provided significantly better lesion detection and characterization than did unenhanced images. With contrast-enhanced images, the detection rate was 79%, compared with 36% for T2-weighted images and 7% for T1-weighted images. Lesion characterization was the best (73%) when all imaging sequences were analyzed. Our study shows that with conventional spin-echo sequences, the use of contrast-enhanced T1-weighted images does not improve the detection or characterization of uterine leiomyomas or adenomyosis but significantly improves the detection of endometrial polyps.

Contrast Media↗
PubMed1992

Recent advances in imaging studies for staging of penile and urethral carcinoma.

Over the past decade, the principal advances in the imaging of genitourinary cancer have come in the fields of ultrasound, CT, and MR imaging. As applied to carcinomas of the urethra and penis, these techniques show promise. The local staging of the lesion may be done with either ultrasound or MR imaging. Ultrasound has correctly staged two penile cancers and predicted the presence or absence of lymph node metastasis. Sonourethrography has been successful in the evaluation of urethral stricture disease and should now be studied for imaging carcinomas of the urethra. Magnetic resonance imaging allows direct tumor visualization. This and its large field of view make it more accurate than clinical staging by palpation. In addition, MR imaging can identify destruction of both the tunica albuginea and the septum between the corpora by metastases to the penis or contiguous involvement by other neoplasms. It also offers the advantage of imaging in three orthogonal planes, giving more anatomic detail of the primary tumor. Tissue contrast is superb, and the study can simultaneously evaluate the pelvic nodes. After careful palpation of the primary tumor and examination of the regional and distant lymph nodes, we perform physical examination under anesthesia and obtain histologic confirmation of the cancer. We then base our decision to obtain further imaging studies on the grade and invasiveness of the tumor along with the findings on physical examination. In patients with tumors that appear to be superficial and are of low grade who have no evidence of regional or distant nodal disease on physical examination, further imaging is not carried out.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma↗
PubMed1991

Carcinoma of the female reproductive organs. Value of cross-sectional imaging.

Cross-sectional imaging techniques i.e., computed tomography (CT) and magnetic resonance imaging (MRI), play an integral role in the evaluation of patients with carcinoma of the female reproductive system. Neither CT nor MRI, however, are tissue-specific, and benign and malignant disease cannot be differentiated using these techniques alone. Therefore, the diagnosis is clinical and is based on history, physical examination, and histology. After the diagnosis has been made, CT and MRI are recommended for noninvasive evaluation of tumor extent, often helping in designing optimal therapy, thus facilitating more effective treatment and ultimately influencing patient prognosis. In evaluating tumors of the uterus, including endometrial and cervical carcinomas, CT is limited to the evaluation of more extensive disease. It is believed that the value of CT rises proportionately to the size and extent of disease. Its major limitation is suboptimal tissue contrast resolution, making differentiation between a small tumor and the surrounding normal tissue difficult. MRI renders excellent soft tissue contrast, allowing direct tumor visualization and assessment of tumor volume, depth of penetration, and extension to adjacent tissues. Assessment of these parameters is crucial in deciding on the choice of therapy, whether surgery, radiation, chemotherapy, or their combination. The initial management of ovarian cancer usually includes surgical staging with tumor debulking. CT remains the primary staging technique; its value resides primarily in identification of tumor metastases and in patient follow-up. Despite progress in the use of CT and MRI, second-look laparotomy for ovarian cancer has not been superseded. Technical advances in radiologic cross-sectional imaging have significantly improved the accuracy of noninvasive tumor staging. Although there are still limitations to these techniques, additional technical improvement and better tissue characterization are imminent.

Female↗
PubMed1991

Cancer of the uterus: the value of MRI pre- and post-irradiation.

In cancer of the uterus, the morphologic factors influencing the choice of therapy and patient prognosis are tumor size, depth of invasion, presence of lymph node metastasis, and stage. Clinical staging is often inaccurate with resultant suboptimal therapy, thereby invalidating comparison between treatment options. The available cross-sectional imaging modalities of ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI), have significantly improved the staging of malignant disease. In the pelvis, MRI offers several advantages over the other imaging modalities. In particular, MRI has excellent soft tissue contrast resolution, allowing direct multiplanar imaging with evaluation of tumor extension in all three directions, and has variable imaging parameters (TR/TE)--characteristics of the echo patterns--to facilitate optimal tumor detection. It is a non-invasive technique with an ability to visualize blood vessels without the need for contrast injection and is independent of body habitus. However, MRI is not tissue-specific and a histological diagnosis is required in all cases. In the post-radiotherapy patient, MRI has the ability to demonstrate radiation tissue change and the potential to differentiate radiation fibrosis from recurrent/residual tumor. Its non-invasive nature and lack of ionizing radiation make it suitable for assessing treatment response and as an adjunct for patient monitoring.

Female↗
PubMed1991

Subclinical varicocele: the effectiveness of varicocelectomy.

To investigate the controversial concept that subclinical varicoceles are detrimental to spermatogenesis, we undertook a prospective study of the effectiveness of surgery in 56 infertile men with clinical and subclinical varicoceles. Our statistical approach specifies improvement as a change from individual baseline level. The over-all variability in sperm counts precluded the demonstration of significant changes in sperm density consequent to surgery. Improvement in sperm motility was seen in both groups, being slightly greater in the subclinical group. The changes were inversely related to baseline levels and increased with time from surgery. Therefore, it appears that the detection of subclinical varicoceles may be warranted in infertile men with abnormal semen parameters.

Humans↗
PubMed1991

Magnetic resonance imaging of renal carcinoma with extension into the vena cava: staging accuracy and recent advances.

In 16 patients with surgical confirmation of inferior vena cava thrombi from renal carcinoma, magnetic resonance imaging (MRI) and computed tomography (CT) were compared to assess the ability of non-invasive, cross-sectional imaging techniques to detect tumour thrombus, the level of its extension, and vessel wall invasion. MRI accurately detected tumour thrombus in the inferior vena cava in all 16 cases (CT in 14) and demonstrated the cephalad extent of tumour thrombi in 15 of 16 (CT in 11). The level of extension was more easily seen on MRI, as was the presence of extension into the hepatic veins--a finding not detected by CT. Tumour invasion of the wall of the inferior vena cava was correctly demonstrated in 7 cases on MRI and in 1 case on CT. In 8 of 16 patients, gradient recall acquisition in steady state (GRASS imaging) was performed in addition to conventional spin echo sequences and it correctly identified the composition of thrombus in all: tumour in 6 patients, blood clot in 1 and both tumour and blood clot in the remaining patient. MRI and CT are excellent for detection of tumour but MRI is superior in the evaluation of vascular extension. In addition, the use of GRASS imaging allows differentiation of tumour from blood thrombus.

Adult↗
PubMed1991

Female urethra: MR imaging.

The potential of magnetic resonance (MR) imaging in the evaluation of the female urethra was studied in 64 patients. Spin-echo T1- and T2-weighted images were obtained in all 64 patients, and contrast-enhanced T1-weighted images were also obtained in 27 patients. Urethral pathologic conditions, established with urethroscopy or histologic examination, or both, included urethral diverticula, inflammatory granuloma, and primary and metastatic neoplasms. On T2-weighted images, all normal urethras demonstrated a characteristic targetlike appearance with differentiation among the outer ring of low signal intensity, the middle zone of higher signal intensity, and the center of low signal intensity. After injection of gadopentetate dimeglumine, the targetlike appearance of the normal urethra was seen on the T1-weighted images. Urethral diverticula were detected with MR imaging in all nine patients with that diagnosis, and in each, MR imaging demonstrated urethral expansion, distortion of the zonal anatomy, and presence of fluid in the middle zone. Primary or metastatic urethral neoplasms were also detected with MR imaging in every patient with the diagnosis, but differentiation between benign and malignant disease was not possible. Local staging of primary or metastatic malignant disease was correct in eight of the 11 patients. In three patients, the inflammatory changes could not be differentiated from tumor invasion, resulting in overestimation of tumor extent.

Adult↗
PubMed1991

Combined gadolinium-enhanced and fat-saturation MR imaging of renal masses.

Combined gadopentetate dimeglumine enhancement and fat-saturation (FS) spin-echo (SE) magnetic resonance (MR) imaging for the detection and characterization of renal masses was evaluated in 43 patients with a total of 71 lesions (28 solid masses and 43 cysts). SE MR sequences compared were the following: short repetition time (TR)/echo time (TE), conventional SE, short TR/TE FS SE, long TR/TE conventional SE, gadolinium-enhanced short TR/TE conventional SE, and gadolinium-enhanced short TR/TE FS SE techniques. MR findings were compared with findings of contrast-enhanced computed tomography (CT) and with pathologic findings in all patients. The sensitivities for detection of renal masses with gadolinium-enhanced FS (71 of 71 lesions) and with gadolinium-enhanced short TR/TE conventional (65 of 71 lesions) SE sequences were significantly (P less than .01) greater than with any unenhanced (short TR/TE conventional [40 of 71 lesions], or long TR/TE [39 of 71 lesions]) SE sequence. Lesion characterization was also best with the gadolinium-enhanced FS SE sequence (65 of 71 lesions correctly classified). When combined pre- and postcontrast short TR/TE FS SE images were analyzed with both qualitative (visual) and quantitative (region-of-interest measurements) assessment, lesion characterization improved even further (70 of 71 lesions were correctly characterized). All lesions detected with CT were visualized with the gadolinium-enhanced FS SE MR sequence, which in addition depicted seven cysts and two small renal cell carcinomas. In summary, the use of gadopentetate dimeglumine, especially when combined with the FS technique, was superior to unenhanced MR imaging for detection and characterization of renal lesions.

Carcinoma, Renal Cell↗
PubMed1991

MR imaging evaluation of endometrial carcinoma: results of an NCI cooperative study.

A prospective study to assess the usefulness of magnetic resonance (MR) imaging in the evaluation of endometrial carcinoma was undertaken by five institutions under the auspices of the National Cancer Institute. Six different MR imagers were used, ranging in magnetic field strength from 0.15 T to 1.5 T. For each unit, appropriate T1- and T2-weighted sequences in the transverse plane and T2-weighted sequences in the sagittal plane were used. Initially, 107 patients were entered in the study, but only 88 fulfilled all the criteria and provide the basis for this study. The abnormality within the endometrial cavity was demonstrated with MR imaging in 81% of the patients. The overall accuracy with MR imaging for staging endometrial carcinoma was 85%. In the evaluation of depth of myometrial invasion for stage I disease, overall accuracy with MR imaging was 74%. The accuracy of MR imaging in assessing tumors confined to endometrium or tumor with superficial myometrial invasion was 89% and decreased to 54% in assessing deep myometrial invasion. The results of this prospective study performed by multiple examiners with vastly different equipment demonstrate the inherent value of MR imaging in the evaluation of this neoplasm.

Adult↗
PubMed1991

Carcinoma of the uterus: use of gadopentetate dimeglumine in MR imaging.

This prospective study assessed the role of gadopentetate dimeglumine-enhanced magnetic resonance imaging in the detection and staging of carcinomas of the endometrium and cervix. Surgical-pathologic findings were used as the standard of reference. In the evaluation of endometrial carcinoma, contrast-enhanced imaging improved tumor detection and differentiation between viable tumor and retained debris. Use of contrast material significantly improved the staging accuracy. The ability to assess the depth of myometrial invasion was also improved. In the evaluation of cervical carcinoma, assessment of tumor location and size did not improve following contrast enhancement. Use of gadopentetate dimeglumine resulted in overestimation of stromal, parametrial, vaginal, and/or bladder wall invasion in eight patients. However, evaluation of intratumoral architecture and large lesions was easier with contrast-enhanced imaging. When only stage II and higher disease was analyzed, use of contrast material improved the evaluation of disease extent. The authors conclude that gadolinium enhancement adds to the accuracy of evaluation of endometrial carcinoma but is useful in only advanced cases of cervical carcinoma.

Adenocarcinoma↗
PubMed1991

Ovarian lesions: detection and characterization with gadolinium-enhanced MR imaging at 1.5 T.

Magnetic resonance (MR) imaging for detection and characterization of ovarian masses was assessed in 33 patients with a total of 60 lesions. Lesions were characterized prospectively as benign or malignant by using T2-weighted MR images and unenhanced and gadolinium-enhanced T1-weighted MR images. MR imaging findings were compared with results of surgical laparotomy performed for staging of lesions. When malignancy was suspected, staging with MR imaging was performed. MR imaging demonstrated 57 of 60 (95%) surgically proved ovarian masses (34 of 36 were benign, 23 of 24 were malignant). Five significant primary criteria and four ancillary criteria for malignancy were established. For all MR pulse sequences combined, characterization of either type of lesion was correct in 84% of cases (48 of 57) when the five primary criteria were used and 95% (54 of 57) were correct when the four ancillary criteria were added. With gadolinium-enhanced images, correct characterization of malignant lesions increased from 56% to 78% with use of the five primary criteria and from 83% to 100% with use of both sets of criteria. Malignancies were correctly staged with MR imaging in 12 of 16 patients. Staging accuracy was 63% with unenhanced images and 75% with the addition of enhanced images.

Adolescent↗
PubMed1991

MR imaging of the seminal vesicles.

MR imaging (0.35 and 1.50 T) was used to assess the appearance of the seminal vesicles. The size and signal intensity of normal seminal vesicles vary with the age of the subject. In general, on T2-weighted images, the signal intensity of normal seminal vesicles is lower than that of fat in prepubertal children, similar to or higher than that of fat in adults, and similar to or lower than that of fat in patients older than 70 years of age. Endocrine and radiation therapy will influence the size and signal intensity of the seminal vesicles. The purpose of the essay is to illustrate the spectrum of seminal vesicle disease, including congenital anomalies, inflammation, and neoplastic disease. Although MR imaging is helpful in depicting seminal vesicle abnormalities, it does not allow differentiation of benign from malignant disease, distinction of hemorrhage due to tumor invasion from postbiopsy changes, or distinguishing between glandular obstruction due to tumor infiltration and mechanical compression.

Genital Diseases, Male↗