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Biomedical subjects

M T Keogan

Publications and source records attributed to M T Keogan.

At least 19 recordsLinked to original sources
PubMed2001

Multiphase contrast-enhanced helical CT of liver metastases from renal cell carcinoma.

The aim of this study was to evaluate whether in patients with metastatic renal cell carcinoma (RCC) multiphase liver studies would improve detection of metastatic liver disease. Forty-six consecutive patients with known metastatic RCC underwent standardized non-contrast and triphasic contrast enhanced hepatic CT examinations as part of their routine imaging studies. Once a liver abnormality was detected, it was characterized as metastatic by a panel of three radiologists who followed pre-set criteria. These criteria included change in size, biopsy results and lack of benign features. Presence and conspicuity of liver metastases were graded using a five-point scale by consensus of a panel of three radiologists. The highest number of lesions evaluated per patient was limited to ten. Seventy-two liver metastases were detected in 16 patients. Of these, 54 were seen on unenhanced scans; 47 in the hepatic arterial (HA) phase, at 25 s; 65 in the portal-venous (PV) phase, at 60 s; and 49 in delayed images, at 90 s. Scanning only during the PV phase would have missed seven lesions (10%), six of which were seen on unenhanced images and six were seen in HA phase. All patients with metastatic liver disease would have been identified by combination of unenhanced and PV phase or by HA and PV phase scanning. Forty-two lesions were graded more conspicuous on the PV phase, whereas 18 (25%) were more conspicuous on the HA phase. The combination of unenhanced, HA and PV scanning should be considered in the initial evaluation of patients with metastatic RCC for improved lesion detection and characterization. Subsequently, the combination of unenhanced and PV phase imaging is preferred.

Adult↗
PubMed2001

Technologic advances in abdominal MR imaging.

Magnetic resonance (MR) imaging is finding an ever-growing role in the evaluation of a wide range of conditions in the abdomen. No longer confined to problem solving regarding abnormalities in solid organs, such as the liver and kidneys, MR imaging is increasingly being applied to the evaluation of the pancreatic and biliary ductal systems and even the bowel. Recent technical advances in hardware and software have allowed the acquisition of MR images that are largely free of artifact secondary to bowel peristalsis or respiratory motion; images providing excellent anatomic detail can now be obtained routinely. Faster sequences have reduced image acquisition time, thereby improving patient acceptance and allowing more efficient utilization of machine time. New three-dimensional sequences allow rapid image acquisition, reducing section misregistration and motion artifact while improving multiplanar reformations. The potential of MR imaging to provide functional and anatomic information is intriguing, and new techniques, including diffusion and perfusion imaging, are being evaluated. This review considers the advances in imaging hardware and pulse sequence design that underlie the increasing role of MR imaging in evaluation of the abdomen and discusses evolving clinical applications.

Abdomen↗
PubMed2001

Impact of multidetector CT on donor selection and surgical planning before living adult right lobe liver transplantation.

OBJECTIVE: This study was performed to document the impact of multidetector multiphase CT in facilitating patient selection and surgical planning in potential donors being evaluated for living adult right lobe liver transplantation. SUBJECTS AND METHODS: Forty consecutive potential donors were included in the study. There were 26 men and 14 women, (age range, 18-57 years; mean, 37 years) We performed CT using a multidetector scanner, after IV injection of 180 mL of contrast material at 5 mL/sec. Arterial phase images were acquired at 18 sec (collimation, 1.25 mm; table speed, 7.5) and portal phase images, at 60 sec (collimation, 2.5 mm; table speed, 15). Postprocessing was performed on a commercially available workstation. CT data included dual-energy assessment of liver parenchyma for fatty infiltration; depiction of arterial, portal venous, and hepatic venous anatomy and identification of important vascular variants; and determination of total and lobar liver volume. RESULTS: Of the 40 potential liver donors evaluated, 15 patients (37.5%) were excluded on the basis of CT findings, with most exclusions a result of portal vein anomalies (n = 8). Fatty infiltration resulted in four exclusions (10%), and small liver volume resulted in three exclusions (7.5%). CONCLUSION: Multidetector multiphase CT provided comprehensive parenchymal, vascular, and volumetric preoperative evaluation of potential donors undergoing living adult right lobe liver transplantation. This information had a major impact on patient selection because it was used to stratify patients. It allowed the surgeons to plan their surgical approach, and this planning may reduce postoperative complications.

Adolescent↗
PubMed2001

Two-dimensional multiplanar and three-dimensional volume-rendered vascular CT in pancreatic carcinoma: interobserver agreement and comparison with standard helical techniques.

OBJECTIVE: The purpose of this study was to compare two-dimensional curved multiplanar and three-dimensional reconstructions, routine axial presentations, and combined techniques in the assessment of vascular involvement by pancreatic malignancy. MATERIALS AND METHODS: For 44 patients with known pancreatic malignancy a total of 56 arterial phase helical CT scans were obtained. Targeted pancreatic imaging was performed, and reformatted images were generated. Axial source images, reformatted images, and the combination of axial and reformatted images were interpreted independently by three observers. The observers graded the celiac axis, common and proper hepatic, splenic, gastroduodenal, and superior mesenteric arteries for tumor involvement. Grades of vascular involvement were compared by intra- and interobserver variability analyses. RESULTS: Intraobserver agreement averaged over five vessels was good between the axial and combined techniques for each individual observer (0.64 < or kappa < or = 0.66), but intraobserver agreement was poor between the axial and reformatted (kappa = 0.17 and kappa = 0.31, respectively) and the reformatted and combined techniques (kappa = 0.31 and kappa = 0.38, respectively) for two observers. For grading of vascular involvement in each vessel, intraobserver agreement was good to excellent between the axial and combined techniques (0.48 or = kappa < or = 0.82). Interobserver agreement averaged over five vessels was poor for imaging techniques except between observer 2 and observer 3 on the axial (kappa = 0.47) and combined techniques (kappa = 0.47). For grading of vascular involvement in each vessel, interobserver agreement for reformatted technique was poor (0.09 < or = kappa < or = 0.40). CONCLUSION: Multiplanar and volume-rendered techniques showed the highest intra- and interobserver variability in grading vascular involvement by pancreatic malignancy. These images should be used in combination with routine axial images to decrease observer variability.

Humans↗
PubMed2000

Vaccines for preventing infection with Pseudomonas aeruginosa in people with cystic fibrosis.

OBJECTIVES: To assess the effectiveness of vaccination against Pseudomonas aeruginosa in patients with cystic fibrosis. SEARCH STRATEGY: The Cochrane Cystic Fibrosis and Genetic Disorders Group specialist trials register which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings. Date of the most recent search of the Group's specialised register: November 1999. SELECTION CRITERIA: All randomised or pseudorandomised trials (published or unpublished) comparing Pseudomonas aeruginosa vaccines (oral, parenteral or intranasal) with control vaccines or no intervention in patients with cystic fibrosis. DATA COLLECTION AND ANALYSIS: We planned to assess the following outcomes: time to infection with Pseudomonas aeruginosa, pulmonary function, body mass index, Schwachman score, frequency of pulmonary infective exacerbations, days of antibiotic usage, days unable to carry out normal daily activities, adverse events, mortality, antibody levels to Pseudomonas aeruginosa and T cell proliferation and cytokine production in response to Pseudomonas aeruginosa. MAIN RESULTS: One trial which included 17 vaccinated patients, with follow up reported to 10 years met the inclusion criteria. Finding only a single trial, and the lack of information on our predefined outcomes limited analysis. REVIEWER'S CONCLUSIONS: There is a paucity of randomised controlled trials assessing the effectiveness of vaccination against Pseudomonas aeruginosa in cystic fibrosis. Increased understanding of modulation of the immune response by vaccination has led to the development of alternative vaccines. We suggest that there is an urgent need for newer vaccines to be evaluated in adequately-powered, multicentre randomised controlled trials examining clinically relevant end-points in addition to immunological variables. Such a trial should assess effectiveness over several years, and include follow-up of vaccinees who become colonised with Pseudomonas aeruginosa.

Bacterial Vaccines↗
PubMed2000

Radiology of urinary diversions.

Radiologic evaluation of urinary diversion has three objectives: to monitor upper tract distention, to detect new urothelial tumors and to detect metastasis. The type of imaging procedure and the frequency of imaging is dictated by the urologist preference. As many surgical procedures are available for noncontinent and continent diversion, interpretation of radiographic studies requires a detailed knowledge of the type of surgical procedure that has been performed.

Cecum↗
PubMed2000

Right lower quadrant pain and suspected appendicitis: nonfocused appendiceal CT--review of 100 cases.

PURPOSE: To determine the value of standard, nonfocused computed tomography (CT) in examining patients with right lower quadrant (RLQ) pain and suspected appendicitis. MATERIALS AND METHODS: The CT scans and medical records of 100 consecutive patients who presented to the emergency department with RLQ pain and were clinically suspected of having appendicitis were retrospectively reviewed. Helical CT of both the abdomen and pelvis was performed at 7-mm increments after oral and intravenous contrast material administration. CT scans were evaluated for the presence of appendiceal or other disease. Results were correlated with surgical and pathologic findings in 34 patients or with 3-month clinical follow-up in 66 patients. RESULTS: CT depicted abnormalities in 66 patients (66%). In 59 (59%) patients, the abnormality was located in the pelvis; 23 (39%) of these patients had appendicitis. Seven (7%) patients had abnormalities outside of the pelvis, a region not typically scanned during focused appendiceal imaging. Four of these seven patients required surgery. Thus, if only pelvic focused RLQ CT had been performed, overall sensitivity would have decreased from 99% to 88% (P <.05) and sensitivity for cases necessitating surgery would have decreased from 96% to 82% (P <.05). CONCLUSION: Both abdominal and pelvic CT examinations are necessary to increase sensitivity and identify the many possible causes of RLQ pain in patients with clinically suspected appendicitis.

Abdominal Pain↗
PubMed2000

Nonenhanced helical CT and US in the emergency evaluation of patients with renal colic: prospective comparison.

PURPOSE: To compare nonenhanced helical computed tomography (CT) with ultrasonography (US) for the depiction of urolithiasis. MATERIALS AND METHODS: During 9 months, 45 patients (mean age, 44 years; mean weight, 92.5 kg) prospectively underwent both nonenhanced helical CT (5-mm collimation; pitch of 1.5) and US of the kidneys, ureters, and bladder. US evaluation included a careful search for ureteral calculi. Presence of calculi and obstruction and incidental diagnoses were recorded. Clinical, surgical, and/or imaging follow-up data were obtained in all patients. The McNemar test was used to compare groups. RESULTS: Diagnoses included 23 ureteral calculi and one each of renal cell carcinoma, appendicitis, ureteropelvic junction obstruction, renal subcapsular hematoma, cholelithiasis, medullary calcinosis, and myelolipoma. CT depicted 22 of 23 ureteral calculi (sensitivity, 96%). US depicted 14 of 23 ureteral calculi (sensitivity, 61%). Differences in sensitivity were statistically significant (P: =.02). Specificity for each technique was 100%. When modalities were compared for the detection of any clinically relevant abnormality (eg, unilateral hydronephrosis and/or urolithiasis in patients with an obstructing calculus), sensitivities of US and CT increased to 92% and 100%, respectively. One case of appendicitis was missed at US, whereas medullary calcinosis and myelolipoma were missed at CT. CONCLUSION: Nonenhanced CT has a higher sensitivity for the detection of ureteral calculi compared with US.

Adult↗
PubMed2000

An investigation into causative factors in patients with bronchiectasis.

Bronchiectasis is a pathologic description of lung damage characterized by inflamed and dilated thick-walled bronchi. These findings may result from a number of possible causes and these may influence treatment and prognosis. The aim of this study was to determine causative factors in 150 adults with bronchiectasis (56 male, 94 female) identified using high-resolution computerized tomography. Relevant factors were identified in the clinical history; cystic fibrosis gene mutation analysis was performed; humoral immune defects were determined by measuring immunoglobulins, IgG subclasses and functional response to Pneumovax II vaccine; assessment was made of neutrophil function (respiratory burst, adhesion molecule expression, and chemotaxis); ciliary function was observed and those likely to have allergic bronchopulmonary aspergillosis (ABPA) were identified. Causes identified were: immune defects (12 cases), cystic fibrosis (4), Young's syndrome (5), ciliary dysfunction (3), aspiration (6), panbronchiolitis (1), congenital defect (1), ABPA (11), rheumatoid arthritis (4), and early childhood pneumonia, pertussis, or measles (44). Intensive investigation of this population of patients with bronchiectasis led to identification of one or more causative factor in 47% of cases. In 22 patients (15%), the cause identified had implications for prognosis and treatment.

Adolescent↗
PubMed1999

Lung cancer staging and management: comparison of contrast-enhanced and nonenhanced helical CT of the thorax.

PURPOSE: To determine whether contrast material-enhanced helical computed tomography (CT) of the thorax and upper abdomen changes the tumor stage and management compared with nonenhanced helical CT in patients with newly diagnosed lung cancer. MATERIALS AND METHODS: During 15 months, any patient in whom lung cancer was strongly suspected or newly diagnosed and who was scheduled for thoracic CT was considered eligible for the study. All patients underwent nonenhanced thoracic helical CT from the lung apices through the adrenal glands and then contrast-enhanced thoracic helical CT from the lung apices through the entire liver. Each study was read independently, and the thoracic radiologic stage was determined. Tissue sampling was performed and the final pathologic stage assigned. RESULTS: Ninety-six patients had a final pathologic diagnosis of lung cancer. There was agreement in stage between the nonenhanced and contrast-enhanced examinations in 92 of the 96 patients. In three patients, the tumor stage at nonehanced CT increased at contrast-enhanced CT, from IA to IIA (n = 1), IIB to IV (n = 1), and IIIB to IV (n = 1). In one patient, the tumor stage decreased from IIIB to IIB. There was no substantial change in management of any patient. CONCLUSION: The results suggest that contrast-enhanced thoracic CT through the liver for staging lung cancer rarely changes the tumor stage determined with nonenhanced CT through the adrenal glands and does not substantially influence management decisions.

Adult↗
PubMed1999

Imaging-guided percutaneous biopsy of focal splenic lesions: update on safety and effectiveness.

OBJECTIVE: The purpose of this study is to determine the safety and effectiveness of percutaneous imaging-guided biopsy in the diagnosis of focal splenic lesions. MATERIALS AND METHODS: From May 1995 to November 1997, 20 imaging-guided biopsies of focal splenic lesions were performed in 18 patients, including seven patients with a prior diagnosis of extrasplenic malignancy (breast cancer, n = 3; lymphoma, n = 2; ovarian cancer, n = 1; and osteogenic sarcoma, n = 1), three immunosuppressed patients (cause of immunosuppression: AIDS, n = 1; liver transplantation, n = 1; and bone marrow transplantation, n = 1), two patients with anemia, one patient with a recent history of IV drug abuse, and five patients with incidentally discovered splenic lesions. Biopsies were performed with an 18-gauge (n = 1), a 20-gauge (n = 8), or a 22-gauge (n = 14) self-aspirating needle or an 18-gauge cutting needle (n = 1). Biopsies were considered successful if a specific diagnosis of benign or malignant disease was made. RESULTS: A specific diagnosis was made in 16 (88.9%) of 18 patients, and no complications occurred. Malignancy was diagnosed in six patients including three patients with lymphoma. Benign conditions were diagnosed in 10 patients: a cyst in two patients; hamartoma in one; lipogranuloma in one; infarct in one; and infection in four, including one case each of Candida albicans, Pneumocystis carinii, Mycobacterium tuberculosis, and mixed flora. The tenth benign diagnosis was a pseudotumor of the spleen related to a bulbous tail of the pancreas that was inseparable from the splenic hilum. Biopsy did not establish a diagnosis in one patient with lymphoma and in one patient with presumed splenic candidiasis. A mean of 1.5 needle passes was made per biopsy. CONCLUSION: Imaging-guided splenic biopsy is a safe technique that provides a specific diagnosis in most patients with focal splenic lesions.

Adult↗
PubMed1999

Comparison of unenhanced, hepatic arterial-dominant, and portal venous-dominant phase helical CT for the detection of liver metastases in women with breast carcinoma.

OBJECTIVE: The purpose of this study was to evaluate triple-phase helical CT for detection of hepatic metastases from breast carcinoma. SUBJECTS AND METHODS: Breast cancer patients were studied prospectively with triple-phase helical CT in 300 consecutive examinations. Hepatic arterial-dominant and portal venous-dominant phase scans were initiated at 20 and 65 sec, respectively, after IV injection of 175 ml of iopamidol (30 mg/ml) at 5 ml/sec. Three independent observers each reviewed 200 cases of the portal venous-dominant phase for lesion number, conspicuity, and attenuation. Subsequently, portal venous-dominant phase images were reevaluated in conjunction with hepatic arterial-dominant phase or unenhanced images. RESULTS: Hepatic metastases were identified in 79 (26%) of 300 cases. Lesions detected on portal venous-dominant, hepatic arterial-dominant, and unenhanced images were as follows: observer 1, n = 198, 164, and 171; observer 2, n = 254, 233, and 233; and observer 3, n = 291, 270, and 276 (p > .05). The mean total lesion count was 387, with more lesions detected on portal venous-dominant phase than on either hepatic arterial-dominant phase or unenhanced images (p < .001 and p < .0001, respectively). For individual observers, 10-26% of lesions were hypervascular on hepatic arterial-dominant phase images. Two to 4% of lesions were identified only on hepatic arterial-dominant phase or unenhanced images. However, in these few cases, the lesions either were false-positives or were seen in conjunction with additional metastases on portal venous-dominant images. CONCLUSION: Routine use of triple-phase CT in patients with breast carcinoma may not be warranted: Addition of the hepatic arterial-dominant phase or unenhanced images revealed few additional lesions in our group of 300 patients.

Adult↗
PubMed1998

Carcinoid metastases to the liver: role of triple-phase helical CT.

PURPOSE: To evaluate triple-phase helical computed tomography (CT) of carcinoid liver metastases. MATERIALS AND METHODS: Triple-phase helical CT was performed in 31 patients with proved carcinoid liver metastases. Hepatic arterial-dominant phase (HAP) and portal venous-dominant phase (PVP) images were obtained 20 and 70 seconds after intravenous iopamidol injection. Four independent readers reviewed each phase for lesion number, conspicuity, and attenuation relative to liver. Three readers reviewed each phase to determine which phase best showed the lesions. RESULTS: The lesions detected by readers 1-4 were as follows: noncontrast phase, 164, 177, 204, and 229 lesions; HAP, 178, 177, 214, and 238 lesions; and PVP, 180, 189, 215, and 250 lesions (P > .05). On HAP images, readers found that 80, 73, 96, and 102 lesions were hyperattenuating. Consensus indicated there were 206 focal lesions. Of these 206 lesions, 72, 72, and 62 lesions were best seen on the noncontrast phase, HAP, and PVP images, respectively. Six, 28, and six lesions were seen only on the noncontrast phase, HAP, and PVP images, respectively. Two patients had lesions seen only on the HAP images. CONCLUSION: The HAP and, to a lesser extent, the noncontrast phase provide added value in evaluating carcinoid liver metastasis.

Carcinoid Tumor↗