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Biomedical subjects

K K Kopecky

Publications and source records attributed to K K Kopecky.

At least 19 recordsLinked to original sources
PubMed2006

Routine isotropic computed tomography scanning of the abdomen and pelvis.

For 30 years, abdominal CT has been imaged and reviewed in the axial plane. It is now possible to carry out isotropic imaging of the whole abdomen and pelvis using a 40-channel scanner. This allows creation of coronal and sagittal reformats with the same image quality as the axial images. In this study, we present our experience of reviewing routinely coronal and, occasionally, sagittal reformats. We discuss situations where these nonaxial reformats are most beneficial.

Adult↗
PubMed2004

Proximal small bowel intussusceptions in adults: CT appearance and clinical significance.

BACKGROUND: According to the clinical literature, intestinal intussusception in adults is rare, is associated with a pathologic lead point, and is usually treated surgically. Nonobstructing small bowel intussusception has been reported as a transient finding on computed tomographic (CT) studies. METHODS: We evaluated the radiographic and clinical findings in 24 patients who were found to have 26 proximal small bowel intussusceptions on abdominal CT scans performed for a variety of indications. RESULTS: Twenty patients with intussusceptions had no evidence of small bowel obstruction. The transient and clinically insignificant nature of 22 intussusceptions in these 20 patients was proven radiologically (n = 14), surgically (n = 1), or by clinical follow-up (n = 7). These patients demonstrated a bowel-within-bowel pattern on multiple contiguous images and absence of strangulation or intestinal dilatation. No lead points were demonstrated in these patients. Three other patients had symptoms of low-grade small bowel obstruction and were treated conservatively. Extensive follow-up investigations showed no recurrence of intussusception or a lead point. One patient had high-grade obstructive intussusception with intestinal ischemia and required surgical resection of necrotic bowel. CONCLUSIONS: Proximal small bowel intussusceptions are likely to be transient and nonobstructive and unlikely to have a significant lead point.

Adult↗
PubMed2001

Evaluation of prospective living renal donors for laparoscopic nephrectomy with multisection CT: the marriage of minimally invasive imaging with minimally invasive surgery.

Laparoscopic technique for excision of a kidney from a living donor has advantages over conventional open surgery, but operative visibility and surgical exposure are limited. Preoperative multisection computed tomography (CT) can provide necessary anatomic information in a minimally invasive procedure. A three-phase examination is suggested: (a) imaging from the top of the kidneys to the pubic symphysis with a section width of 2.5 mm and no contrast medium, (b) scanning of the kidneys and upper pelvis during the arterial phase of enhancement with a section width of 1.0 mm, and (c) scanning of the kidneys and upper retroperitoneum during the nephrographic phase of enhancement with a section width of 1.0 mm. Emphasis in this article is placed on analysis of the venous anatomy because most radiologists are unfamiliar with the anatomic variations. Conventional radiography of the abdomen and pelvis is performed after CT to evaluate the collecting system and ureters and to provide a lower total radiation dose than if CT were used. Of several postprocessing techniques that may be used, the authors prefer maximum intensity projection for arterial evaluation and multiplanar reformatting for venous evaluation.

Humans↗
PubMed1999

An initial experience with screening for colon polyps using spiral CT with and without CT colography (virtual colonoscopy)

BACKGROUND: Computed tomographic (CT) colography (virtual colonoscopy) is a new imaging method for detection of colon polyps and cancer. OBJECTIVE: To evaluate the sensitivity of CT colography for polyp detection in a population without symptoms that included persons without colon neoplasia and with radiologists blinded to colonoscopic findings. METHODS: Forty-six persons without symptoms underwent spiral CT followed by same-day colonoscopy with subsequent inspection of two-dimensional axial CT images, interactive multiplanar images, and surfaced and volume-rendered images of the colon (three-dimensional CT colography). RESULTS: Three-dimensional CT colography was superior to two-dimensional axial imaging for detection of colon polyps. Three-dimensional CT colography depicted 1 of 4 (25%) adenomas 2 cm in diameter or larger, 6 of 10 (60%) adenomas 1 to 1.9 cm, 6 of 14 (43%) 6 to 9 mm, and 7 of 65 (11%) 5 mm in diameter or smaller. Three-dimensional CT colography showed a polyp that might have led to colonoscopy in 3 of 4 (75%) patients whose largest adenoma was 2 cm or larger, 5 of 6 (83%) patients with largest adenoma 1 to 1.9 cm, 3 of 7 (43%) patients with largest adenoma 6 to 9 mm, and 4 of 16 patients (25%) with largest adenoma 5 mm or smaller. Large, flat adenomas of the right colon were difficult to identify with three-dimensional CT colography. The specificity of three-dimensional CT colography for patients with adenomas 1 cm in diameter or larger was 89%. Examination of patients with missed adenomas after unblinding indicated that meticulous bowel preparation and adequate distention are critical to accurate interpretation. Perceptual errors were common. CONCLUSIONS: CT colography as performed in this study is not adequate as a colorectal cancer screening test. Several technical factors that appear critical to accurate performance of CT colography are defined.

Adenocarcinoma↗
PubMed1999

Screening for hepatocellular carcinoma in patients with advanced cirrhosis.

OBJECTIVE: Most available data on screening for hepatocellular carcinoma (HCC) in patients with cirrhosis originate from Asia and Europe. These data may not be applicable to patients from the United States because of geographic variation in the underlying etiology and other factors. Our aim was to assess the risk of HCC in U.S. patients with cirrhosis undergoing standardized screening. METHODS: All cirrhotic patients evaluated for liver transplantation at our institution from January 1, 1994-December 31, 1997 were included in this study. The screening strategy included initial screening, which was offered to all patients and consisted of alpha-fetoprotein (AFP), abdominal ultrasound, and computed tomography (CT) scan, and extended screening, which was performed only on transplant-eligible patients and consisted of semiannual AFP and ultrasound. RESULTS: During the study period, 285 patients with cirrhosis were evaluated for transplantation and underwent initial screening. Of these, 166 were eligible for transplantation and underwent extended screening during a median follow-up of 15 months (range 6-42 months). Twenty-seven HCC were found, 22 during initial screening and five during extended screening. The cancer-free proportions of the cohort who underwent extended screening at 1, 2, and 3.5 yr were 98.6% +/- 1.4%, 96.4 +/- 1.8%, and 77.1% +/- 1.7%, respectively (mean +/- SE). Hepatitis C, either alone or in part, was the etiology in 63% of patients with HCC. The sensitivity of CT scan (88%) was significantly higher than AFP >20 ng/ml (62%) and ultrasound (59%) for detecting HCC (p < 0.001). CONCLUSIONS: In patients with established cirrhosis, the risk of detecting HCC is maximal at the baseline screening (7%). Hepatitis C was the most common etiology for cirrhosis in study. In U.S. patients with established cirrhosis, CT scan exhibited higher sensitivity for detecting HCC than ultrasound or AFP.

Adult↗
PubMed1999

Thermoacoustic CT with radio waves: a medical imaging paradigm.

The authors evaluated images obtained with a prototypic thermoacoustic computed tomographic (CT) scanner constructed for use at 434 MHz, a promising radio frequency for detecting breast cancer. In one excised porcine kidney, acoustic energy emanating from the kidney was detected with transducers. The resultant electric signals were used to create a three-dimensional data set. Two-dimensional images reconstructed in multiple planes were compared with state-of-the-art T1- and T2-weighted magnetic resonance images. The renal outline, parenchyma, and collecting system were clearly delineated on the thermoacoustic CT images.

Acoustics↗
PubMed1999

Temporal bone: comparison of isotropic helical CT and conventional direct axial and coronal CT.

OBJECTIVE: The objective of the study was to compare helical CT (with reformation of coronal images from the axial data set) with conventional direct axial and coronal CT of the temporal bones. SUBJECTS AND METHODS: Nineteen patients underwent both conventional 1-mm direct axial and coronal CT and helical 0.5-mm axial CT. The helical data set was reconstructed at 0.2-mm increments, and axial and coronal images were reconstructed in a plane similar to that of the conventional study, with a slice width of 0.5 mm and 0.5-mm increments. Forty small structures were evaluated independently by three observers, who were unaware of the method of imaging. Observers graded the 40 structures using a modified Likert scale. The graded differences between the two techniques were evaluated using a paired t test. Correlation between observers' gradings was evaluated using analysis of variance. RESULTS: The helical CT technique scored significantly higher than the conventional technique for many individual structures and groups of structures (scutum [p = .041], stapes footplate [p = .006], stapes crura [p = .004], oval window [p = .026], crista falciformis [p = .006], whole temporal bone [P = .012], middle ear [p = .033], inner ear [p = .021], ossicles [p = .044], and stapes [p = .010]). The correlation coefficient among observers was .91 for the whole temporal bone. CONCLUSION: Helical CT using 0.5-mm technique and reconstruction produces diagnostic images comparable with or superior to conventional 1-mm technique because helical CT can obtain thinner slices.

Adolescent↗
PubMed1999

Classification and management of perforations complicating endoscopic sphincterotomy.

BACKGROUND: The management of perforations after endoscopic sphincterotomy (ES) is controversial. The purpose of this study was to analyze the treatments and outcome of patients with ES perforations. METHODS: Between January 1994 and July 1998, in a series of 6040 endoscopic retrograde cholangiopancreatographies, 2874 (48%) ESs were performed: 40 patients (0.6%) with perforation were identified and retrospectively reviewed. RESULTS: All patients (n = 14) with guidewire perforation (group I) were recognized early, managed medically, and discharged after a mean hospital stay of 3.5 days. Twenty of 22 patients with periampullary perforation (group II) were identified early; 18 patients (90%) had aggressive endoscopic drainage, and none required operation. Of the 2 patients identified late, 1 patient required operation and subsequently died. Mean hospital stay for this group was 8.5 days. Only 1 of 4 patients with duodenal perforations (group III) was identified early; all required operation; 1 patient died, and the mean hospital stay was 19.5 days. CONCLUSIONS: ES perforation has 3 distinct types: guidewire, periampullary, and duodenal. Guidewire perforations are recognized early and resolve with medical treatment. Periampullary perforations diagnosed early respond to aggressive endoscopic drainage and medical treatment. Postsphincterotomy perforations diagnosed late (particularly duodenal) require surgical drainage, which carries a high morbidity and mortality rate.

Abscess↗
PubMed1998

Gender differences in alcohol metabolism: relationship to liver volume and effect of adjusting for body mass.

BACKGROUND & AIMS: Alcoholic liver disease purportedly develops more readily in women than in men. Some studies have demonstrated faster rates of alcohol elimination in women. This study examined whether gender differences in alcohol metabolism are related to differences in liver volume and/or differences in lean body mass. METHODS: Ten men and 10 women had alcohol elimination rates determined by clamping of the breath alcohol concentration at 50 mg/dL by means of a constant rate of intravenous infusion of 6% ethanol. Liver volume was determined by computed tomography. RESULTS: Mean alcohol elimination rate and mean computed liver volume were not significantly different in men and women. Lean body mass was 42% greater in men than in women. Consequently, the calculated alcohol elimination rate and liver volume per kilogram of lean body mass were 33% and 38% higher in women than in men, respectively. When the alcohol elimination rate was calculated per unit liver volume, no gender-related difference was found. CONCLUSIONS: Women have greater clearance of ethanol per unit lean body mass, confirming previous oral alcohol administration studies. Women have approximately the same liver volume as men, explaining the equivalent alcohol elimination rates seen when men and women are compared on the basis of liver size.

Adult↗
PubMed1998

Objective measurement of motion in patients undergoing spiral CT examinations.

PURPOSE: To develop and evaluate an objective measurement of patient motion during spiral computed tomography (CT). MATERIALS AND METHODS: An acrylic rod was attached along the length of the torso in 109 patients (56 women, 53 men; age range, 21-79 years; mean age, 51 years) who underwent abdominal spiral CT examinations. Subjective evaluation of motion was graded on a five-point scale by two radiologists. Objective measurements of motion were determined by means of computer reconstruction of the rod in three dimensions and calculation of the deviation of the rod from its estimated position in the motionless state with time. RESULTS: Complete data were available in 98 patients. Subjective and objective measurements of patient motion showed a moderately high Spearman correlation coefficient of .49 (P < .001). The correlation between either observer and objective measurements was similar to the correlation between one observer and the other. CONCLUSION: This objective technique for assessing patient motion correlated well with subjective methods and may be useful in evaluating scanning parameters that may affect patient motion and hence scan quality.

Artifacts↗
PubMed1998

Identification of clinical stage A nonseminomatous testis cancer patients at extremely low risk for metastatic disease: a combined approach using quantitive immunohistochemical, histopathologic, and radiologic assessment.

PURPOSE: To evaluate previously determined predictors of metastasis in low-stage testis cancer in a consecutive group of clinical stage A patients. PATIENTS AND METHODS: Ninety-one consecutive clinical stage A nonseminomatous germ cell tumor (NSGCT) patients who underwent primary nerve-sparing retroperitoneal lymph node dissection (NSRPLND) had orchiectomy specimens and computed tomographic (CT) scans evaluated blindly in a quantitative fashion. These scores were then correlated with pathologic stage using previously determined paradigms. RESULTS: Using volume of embryonal carcinoma in the orchiectomy specimen, lymph node diameters in the primary landing zones and MIB-1 staining of the orchiectomy specimen, 41 patients were classified as low risk for metastasis. Forty of these 41 had pathologic stage A disease at RPLND. CONCLUSION: These parameters can identify a low-risk group of patients for metastasis who can be rationally offered surveillance.

Carcinoma, Embryonal↗
PubMed1997

Comparison of ultrasound-fine needle aspiration and computed tomography in patients undergoing elective neck dissection.

BACKGROUND: Ultrasound of the neck with fine needle aspiration (US-FNA) of suspicious lymph nodes has potential advantages over other radiologic techniques as a screening method for the NO neck in head and neck cancer. METHODS: Twenty-five patients with head and neck cancer who underwent both US of the neck with FNA of any suspicious lymph nodes and neck computed tomography (CT) prior to elective neck dissection were studied. The majority of patients had squamous cell carcinoma (SCC) of the upper aerodigestive tract. Histopathologic results of the neck specimens were compared with each screening technique (palpation, US, US-FNA, CT). RESULTS: Computed tomography (87.9%) and US-FNA (84.9%) had similar overall accuracy in terms of screening the NO neck in our study and were superior to palpation (69.7%) and US alone (72.7%). Specificity was 100% for both CT and US-FNA, with a sensitivity of 60% for CT and 50% for US-FNA. Ultrasound-FNA and CT showed false-negative examinations on virtually the same cases. CONCLUSIONS: Overall, US-FNA was comparable to CT in screening the NO neck in our study. The choice of which modality to employ for imaging the clinically negative neck depends on a number of factors, including the location and clinical extent of the primary tumor as well as the experience and preference of the head and neck surgeon and radiologist.

Biopsy, Needle↗
PubMed1997

Value of helical computed tomography, angiography, and endoscopic ultrasound in determining resectability of periampullary carcinoma.

BACKGROUND: High-quality preoperative radiographic evaluation is crucial in selecting patients with periampullary carcinomas who are candidates for surgical exploration and tumor resection while minimizing the rate of unnecessary laparotomy. METHODS: Twenty-one consecutive patients were prospectively investigated using helical computed tomography (CT) scanning, endoscopic ultrasonography (EUS), and selective visceral angiography (SVA) to determine tumor resectability. All patients were explored and resectability determined. RESULTS: Helical CT had a sensitivity of 63%, a specificity of 100%, and an overall accuracy of 86%. EUS had a sensitivity of 75%, a specificity of 77%, and an overall accuracy of 76%. SVA had a sensitivity of 38%, a specificity of 92%, and an overall accuracy of 71%. CONCLUSIONS: Helical CT scanning is the best preoperative imaging test to determine tumor resectability. EUS is more sensitive than CT for tumor detection, but underestimates resectability. SVA is no longer helpful in the preoperative evaluation of these malignancies.

Aged↗