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R K Zeman

Publications and source records attributed to R K Zeman.

At least 19 recordsLinked to original sources
PubMed1999

Viewing DICOM-compliant CT images on a desktop personal computer: use of an inexpensive DICOM receive agent and freeware image display applications.

OBJECTIVE: Our objective was to determine the ease of installation and use of relatively inexpensive and free software applications that allow Macintosh users to receive and view CT images from a Digital Imaging and COmmunication in Medicine-compliant imaging network. CONCLUSION: Simple-to-use Macintosh-based options to transfer and view images are readily available and easily installed by users with minimal computer expertise.

Humans↗
PubMed1998

Imaging of the liver with helical CT: a survey of scanning techniques.

OBJECTIVE: We conducted a survey of the members of the Society of Computed Body Tomography/Magnetic Resonance to assess current techniques in liver imaging using helical CT. MATERIALS AND METHODS: The survey, which was designed to update earlier surveys from 1987 and 1993, included a questionnaire distributed to 77 members of the Society of Computed Body Tomography/Magnetic Resonance. RESULTS: Forty-nine members responded, representing 28 institutions. In 1993, 19% (5/26) of institutions used helical scanners, compared with 82% (23/28) in 1996. The group of institutions with helical CT served as the focus of this survey. In 1993, 58% of institutions used 1-cm collimation: in 1996, 78% (18/23) used thinner, 7- to 8-mm collimation. In 1987, 41% used power injectors compared with 85% in 1993 and 100% in 1996. In 1996, monophasic injections were used by 96% (22/23) of institutions. In 1993, most institutions used a contrast material injection rate of 1.5-2.0 ml/sec; in 1996, most used a 2.5-3.0 ml/sec injection rate. In 1993, 96% of institutions used 125-150 ml of contrast material; in 1996, 57% (13/23) of institutions used 125-150 ml and 30% of institutions used less than 125 ml of contrast material. A delay time of 21-45 see was used by 83% of institutions in 1993, whereas in 1996, 83% (19/23) of institutions used a longer delay time of 50-80 sec. In 1996, 13% of institutions used an individual scan delay technology and all institutions performed multiphasic scanning of hypervascular lesions. CONCLUSION: The availability of helical CT has changed radiologists' approach to liver imaging. The greatest effects of which are a more widespread use of power injectors, longer delay times, thinner collimation, increased contrast material injection rates, decreased contrast material volumes, and multiphasic scanning.

Contrast Media↗
PubMed1997

Solitary fibrous tumors: a series of lesions, some in unusual sites.

Solitary fibrous tumor (SFT) is a rare neoplasm that, in addition to its classic presentation as a pleural-based mass, can also be encountered in unusual sites. The main difficulty in making the diagnosis of SFTs results from the unfamiliarity with its diverse clinical and pathologic features. This series of SFTs, some with unusual clinicopathologic presentation, included nine women and two men, ranging in age from 28 years to 74 years (five in pleura, one in lung parenchyma, one in breast, and four in mediastinum). The tumors were locally excised in eight cases and were resected along with portions of lung parenchyma in three. A panel of immunohistochemical stains was used to characterize these tumors. They were all vimentin-positive and, with the exception of one case, CD34-positive. Tumors were negative with antibodies directed against cytokeratin, factor VIII-related antigen, S-100 protein, muscle-specific actin, and smooth-muscle actin. Various diagnoses were initially rendered for these clinically and pathologically diverse lesions by the examining pathologists. Awareness of the various gross and microscopic patterns of these tumors, the possibility of occurring in unusual sites, and the use of immunohistochemical stains, particularly CD34, should eliminate most of the difficulties in arriving at a correct diagnosis. One patient died of metastatic breast cancer; all other patients were alive and well with a median follow-up of 17 months.

Adult↗
PubMed1997

TNM staging of pancreatic carcinoma using helical CT.

OBJECTIVE: The purpose of this study was to determine the accuracy of helical CT scanning in predicting the stage of carcinoma of the exocrine pancreas using TNM staging guidelines and in predicting resectability of carcinoma of the exocrine pancreas. MATERIALS AND METHODS: Twenty-six patients with proven adenocarcinoma of the pancreas underwent uniphasic or biphasic helical CT scanning. Two observers unaware of the patient's surgical stage evaluated the CT examinations using the TNM system (with specific assessment and description of disease sites). In addition, the two observers rated confidence of nonresectability using a 5-point scale (ranging from 1, definitely resectable, to 5, definitely not resectable). Observer results and preoperative interpretations were compared with surgical findings. RESULTS: Nineteen of 26 patients had nonresectable disease. The combined observer scores showed correct determination of T stage in 77% of patients, of N stage in 58%, and of M stage in 79%. The overall accuracy in determining lack of resectability was 96% and 84% for the two observers. All errors in determining resectable versus nonresectable disease occurred when the observer was not maximally confident of his or her diagnosis. CONCLUSION: Helical CT is an effective screening technique for assessing T and M stages of pancreatic carcinoma. However, helical CT is poor at detecting regional lymph node involvement. In patients with equivocal T-stage findings (such as questionable venous involvement), other studies such as endoscopic sonography may be of value.

Adenocarcinoma↗
PubMed1996

MR imaging appearance of the uterus in postmenopausal women receiving tamoxifen therapy for breast cancer: histopathologic correlation.

PURPOSE: To describe the spin-echo and dynamic gadolinium-enhanced magnetic resonance (MR) imaging appearance of the uterus in women receiving tamoxifen. MATERIALS AND METHODS: Thirty-five postmenopausal women with breast carcinoma receiving tamoxifen therapy underwent pelvic MR imaging. T1-weighted, T2-weighted, and dynamic gradient-echo T1-weighted sequences were used. Twenty-seven patients underwent uterine sampling within 3 months of MR imaging. RESULTS: Endometrial width on T2-weighted images ranged from 0.1 to 7.5 cm (mean thickness, 1.1 cm). Two uterine imaging patterns were noted. Patients with pattern 1 findings had homogeneous high signal intensity of the endometrium on T2-weighted images (mean, 0.5 cm) and enhancement of the endometrial-myometrial interface and a signal void in the lumen on gadolinium-enhanced images (18 patients). Patients with pattern 2 findings had heterogeneous endometrial signal intensity on T2-weighted images (mean, 1.8 cm) with enhancement of the endometrial-myometrial interface and latticelike enhancement traversing the endometrial canal on gadolinium-enhanced images (17 patients). Other imaging findings included subendometrial cysts, nabothian cysts, leiomyoma, and adenomyosis. Ten patients with pattern 1 findings had atrophic or proliferative endometria at histopathologic analysis; 12 of the 17 patients with pattern 2 findings had polyps, one of which had a focus of endometrial carcinoma. CONCLUSION: MR imaging of the uterus showed two distinct patterns in women receiving tamoxifen therapy.

Adult↗
PubMed1996

Helical (spiral) CT of the upper airway with three-dimensional imaging: technique and clinical assessment.

OBJECTIVE: The purpose of this study was to evaluate the application of helical CT-generated three-dimensional images of the upper airway. MATERIALS AND METHODS: Thirty patients, 10 healthy and 20 with upper-airway disease, were studied with helical CT (5-mm collimation). Overlapping images at 2-mm intervals were retrospectively generated. In the group of healthy patients, two radiologists in independently compared overlapping with nonoverlapping images, ranked confidence in identifying small airway structures on a scale of 1-5, and tabulated the number of images demonstrating these structures. In the 20 patients with disease, three-dimensional (3D) surface models were rendered on an independent workstation and were reviewed by two radiologists and one otolaryngologist for image quality, appreciation of lesion morphology, and ability to judge lesion extent, using a similar scale. A phantom was used to optimize parameters for the 3D reconstructions. RESULTS: Viewing of the retrospectively generated overlapping images increased by 122% the number of images in which laryngeal and hypopharyngeal structures could be identified (p < .01). Image confidence scores for the radiologists averaged 3.3 for nonoverlapping and 4.0 for overlapping (p < .05). Radiologists and otolaryngologist rated the quality of the 3D images equally. The otolaryngologist's assessment of the value of the models for understanding the lesion morphology was 3.5 compared with the radiologists assessment of 2.5; and for judging the lesion extent, the otolaryngologist's assessment was 3.8 compared with 2.7 for the radiologist, a statistical significance of p < .01. CONCLUSION: Helical CT with the application of overlapping images and 3D reconstructions significantly assists the understanding of upper-airway disease.

Case-Control Studies↗
PubMed1996

Assessment of a technology that permits individualized scan delays on helical hepatic CT: a technique to improve efficiency in use of contrast material.

OBJECTIVE: We performed this study to assess the usefulness of a computer automated scan technology (CAST) for individualizing scan delay during helical CT to improve the efficiency of hepatic enhancement. SUBJECTS AND METHODS: We prospectively evaluated 183 patients who were randomized into five groups. Control patients received 100 or 150 ml of contrast material (320 mg I/ml) with a 60-sec delay between contrast injection at 3 ml/sec and scanning. CAST patients received 100, 125, or 150 ml. In our latter groups we used an hepatic enhancement threshold of 50 H over baseline to determine the optimum delay between contrast injection and scanning. For the intergroup comparisons, we measured the liver on baseline and enhanced helical CT scans at the upper, mid, and lower levels of the liver. RESULTS: The mean enhancement in patients who received 150 ml of contrast material was 70.7 +/- 19.4 H for the control group and 81.0 +/- 17.5 H for the CAST group (p < .05). Hepatic enhancement above 50 H was achieved in 84% of the control subjects compared with 100% of CAST subjects; more than 60 H hepatic enhancement was achieved in 73% of control subjects and in 89% of CAST subjects. The use of CAST software with 125-ml contrast doses provided enhancement equivalent to that of control subjects who received 150 ml of contrast material (mean enhancement in CAST subjects, 70.3 +/- 15.4 H). Enhancement above 50 H was reached in 98% of CAST and 84% of control patients. With 100 ml of contrast material, 24% of patients failed to initiate CAST, resulting in enhancement similar to control patients (CAST, 54.2 +/- 11.4 H; controls, 56.9 +/- 15.2 H). CONCLUSION: Using a contrast dose of 150 ml, CAST provided significantly increased hepatic enhancement than that achieved in control subjects with less variability. For equivalent hepatic enhancement, contrast doses could be decreased by 25 ml using CAST technology because it provides individualized scan delays.

Adult↗
PubMed1996

Helical CT of renal masses: the value of delayed scans.

OBJECTIVE: Routine scanning techniques used for helical CT of the abdomen result in dense cortical opacification of the kidney, whereas the medulla and collecting system are not well opacified, which potentially compromises detection of renal masses. The purpose of this retrospective study was to determine if additional delayed views (taken approximately 2-4 min after the start of injection of contrast material) are necessary for the detection and characterization of renal masses. MATERIALS AND METHODS: Early (60-70 sec after the start of the injection of contrast material) and delayed scans of 40 patients with suspected renal masses were blindly evaluated by two observers. The patients harbored a total of 187 renal masses (including 62 solid masses). Each region of the kidney (upper, middle, and lower pole) was scored for the presence of a mass. Scoring was done as a binary decision and also as a five-point confidence score for receiver operating characteristic analysis. RESULTS: We found 97 regions that contained renal masses and 114 regions that did not. Receiver operating characteristic analysis revealed the observers to have significantly greater confidence in detection of renal masses on the delayed scans. The binary data showed the two observers to have a sensitivity of 97% for delayed scans versus 77% (p = .0002) and 89% (p = .027), respectively, for the early scans. For the first observer, early and delayed scans were of equal specificity, but for the second observer, the delayed scans yielded greater specificity (94% versus 85%, p = .024). On the early scans, both observers were significantly more likely to miss a neoplastic lesion than a nonneoplastic lesion. The less experienced of the two observers also tended to have greater difficulty in characterizing the lesions on the early scans. CONCLUSION: Because of the significant risk of missing a renal mass, especially a neoplasm, on early cortical-phase scans, additional delayed scans appear justified when a renal mass is suspected on the basis of other imaging tests or clinical history.

Adult↗
PubMed1995

AIDS-associated intussusception in young adults.

We have examined the changing demographics of adult intussusception and implicate human immunodeficiency virus (HIV)- and acquired immune deficiency syndrome (AIDS)-associated gastrointestinal pathology as risk factors for intussusception in young adults. The clinical index of suspicion for intussusception should be raised for an HIV-positive young adult with intermittent crampy abdominal pain. Over a 10-year period, eight cases of adult intussusception were diagnosed at our institution, and we reviewed the diagnostic computed tomography (CT) scans and records of these patients to correlate them with radiological studies, clinical history, surgical findings, laboratory studies, pathologic analysis, and outcome. Three of the eight patients with adult intussusception had AIDS, all diagnosed by CT scans. Their average age was 41 years, whereas average age of the non-HIV-associated patients was 63. These findings suggest that HIV- and AIDS-associated gastrointestinal pathology provide lead points for intussusception and are significant risk factors for intussusception in young adults. We reviewed the five previously reported cases of AIDS and intussusception and conclude that intussusception should be a diagnostic consideration in an HIV-positive young adult with abdominal complaints. It is clear that AIDS-associated intussusception is a real clinical problem and that CT is an effective method of diagnosing it.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Helical CT: practical considerations and potential pitfalls.

Helical (spiral) computed tomography (CT) is having a dramatic impact on body imaging. Unlike conventional CT, helical CT provides continued volumetric acquisition as the patient moves through the gantry. Advantages of helical CT include dramatically shortened examination times, improved visibility of vascular structures, better enhancement of parenchymal organs, the capability for retrospective imaging and three-dimensional (3D) vascular studies, and potential reduction in use of contrast material. However, helical CT requires one to be more cognizant of the relationship between contrast material administration and scanning, since the optimal temporal window for detection of disease can be missed. Factors unique to helical technology can produce artifacts, which one must be aware of when interpreting helically generated scans. Many of these artifacts relate to accentuation of vascular or parenchymal enhancement. Others occur during production of high-quality 3D images. Additional artifacts are sure to be identified with increased experience with helical CT.

Aortic Dissection↗
PubMed1995

Biliary tract: three-dimensional helical CT without cholangiographic contrast material.

Bile duct anatomy depicted with a three-dimensional (3D) model developed with helical computed tomography (CT) data was compared with cholangiographic depiction. The ductal system was completely displayed from all angles in four of six patients, as well as the stricture and length of bile duct between strictures and the bifurcation in five of six cases. 3D rendering can depict preoperative ductal anatomy.

Adult↗
PubMed1995

Three-dimensional imaging of the hypopharynx and larynx by means of helical (spiral) computed tomography. Comparison of radiological and otolaryngological evaluation.

A new computed tomography (CT) technology, helical (spiral) CT, allows the entire neck to be imaged in only 30 seconds. Although multiplanar and three-dimensional (3-D) imaging could be performed with conventional CT, the volumetric acquisition provided by helical (spiral) CT allows significantly improved quality and easier reconstruction for more applications. These 3-D models show an airway appearance similar to that obtained with laryngography. Independent review of the 3-D images in 12 patients with lesions by two radiologists and one otolaryngologist was performed to assess 1) image quality, 2) ability to judge lesion extent, and 3) assistance in understanding the lesion compared to that provided by routine axial scans. Rating scores of 1 to 5 were assigned, with 5 representing the best quality or greatest value. The results showed that both groups scored image quality equally: 4.7. Lesion extent for the radiologists was 2.6, while the otolaryngologist's ranking was 3.7 (p < .01). In assisting understanding of lesions versus axial scans, radiologists ranked 3-D images 2.1, while the otolaryngologist ranked them 3.1 (p < .01). In summary, 3-D models provide a complementary imaging technique in understanding upper airway disease.

Artifacts↗
PubMed1995

Conspicuity of hepatic metastases on helical CT: effect of different time delays between contrast administration and scanning.

OBJECTIVE: The purpose of this study was to compare two time delays between injection of contrast material and helical CT scanning to determine relative conspicuity of hepatic metastases. SUBJECTS AND METHODS: Twenty-five patients with hepatic metastases were examined with helical CT. The first imaging phase was initiated at 50 sec and the second 75 sec after the start of contrast material injection (3 ml/sec, 150 ml). Differences in lesion and liver attenuation were measured quantitatively. Four radiologists used a 5-point scale to assess lesion conspicuity subjectively. RESULTS: Mean differences in enhancement between liver and lesion were 41 H during the first phase and 59 H for the second phase (p = .0001). Radiologists' conspicuity score averaged 2.4 for lesions in the first phase versus 3.3 for lesions in the second phase (p = .0001). In 56 (88%) of 64 lesions, objective measurements showed greater enhancement of lesions during the later phase. Radiologists found 60 (94%) of 64 lesions to be more conspicuous on these later images. CONCLUSION: Our results show that conspicuity of hepatic metastases on helical CT scans is better with a 75-sec scan delay between contrast administration and scanning than with a 50-sec scan delay. The longer delay time should be used when scanning is used to detect metastases.

Adult↗
PubMed1995

Abdominal aortic aneurysms: findings on three-dimensional display of helical CT data.

Excellent vascular opacification, reduction in misregistration artifacts, and the option of reconstructing overlapping scans from which three-dimensional (3D) models of the abdominal vessels may be rendered are among the benefits of helical CT [1-4]. The purpose of this essay is to illustrate the findings of 3D rendering of helical CT data in patients with abdominal aortic aneurysms.

Aortic Aneurysm, Abdominal↗
PubMed1995

Diagnosis of aortic dissection: value of helical CT with multiplanar reformation and three-dimensional rendering.

OBJECTIVE: Twenty-three patients with suspected aortic dissection were evaluated in this preliminary study of helical CT to determine the usefulness of axial sections, multiplanar reformation, and three-dimensional (3D) rendering in assessing the presence of dissection and the extent of intimal flap. MATERIALS AND METHODS: Patients were referred for helical CT scanning because of chest pain or an abnormal chest radiograph. Scans were performed during bolus injection of nonionic contrast material at 2.0-2.5 ml/sec using a mean scan delay of 47 sec. Axial scans with 5-mm collimation were obtained in all patients. They extended from the great vessels to the distal thoracic aorta just above the hiatus. Delayed nonhelical sections were obtained through the upper abdomen. Multiplanar reformations and 3D models were reconstructed from the helical data in 13 patients and were compared to axial sections in 7 patients who proved to have documented dissection. The efficacy of CT was determined using surgery, angiography, or clinical outcome to establish the diagnosis. RESULTS: Of the 23 patients studied, axial sections resulted in 15 true-negative, 7 true-positive, and 1 false-positive interpretation. In three of seven patients with dissection, it was difficult to determine the extent of the intimal flap on axial sections; multiplanar reformation or 3D views clarified the relevant anatomy in all 3 cases. Among the 3D display methods, ray-sum projection views were superior to surface model or maximum-intensity-projection views. CONCLUSION: If studies of larger numbers of patients confirm our preliminary findings, multiplanar reformation and 3D rendering of helical CT scans will be a valuable addition to axial display of CT studies used to detect aortic dissection and to determine the extent of the intimal flap.

Adult↗