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Biomedical subjects

D S Katz

Publications and source records attributed to D S Katz.

At least 19 recordsLinked to original sources
PubMed2001

Unenhanced helical computed tomography for the evaluation of suspected renal colic in the adolescent population: a pilot study.

OBJECTIVES: Unenhanced helical computed tomography (UHCT) is rapidly becoming the preferred imaging modality for the evaluation of suspected renal colic in the adult population; however, a series addressing its use in the adolescent population has not been previously published. We assessed the utility of UHCT in the evaluation of suspected renal colic in this age group. METHODS: Seventeen patients between the ages of 8 and 18 years (mean 14.7) presented to the emergency departments of four hospitals for evaluation of suspected renal colic. All patients were studied with UHCT immediately after initial evaluation. A single helical acquisition was performed from the midpoint of T-12 vertebra to a point below the bladder base, using a slice thickness of 5 mm. Films were reviewed by the institutional radiologist, and results were quantified. RESULTS: Of the 17 patients who underwent evaluation, no abnormality was detected in 8 patients. A stone was localized in 7 patients who were then appropriately treated. One patient had no stone visualized, but secondary signs suggested a recently passed stone. The final patient had no stone; however, marked bilateral hydroureteronephrosis was noted that led to further evaluation. A single phlebolith was seen in only 1 patient, and no study was nondiagnostic. CONCLUSIONS: UHCT is a safe, rapidly performed test for the evaluation of suspected renal colic in adolescents. It is highly sensitive and specific for renal and ureteral calculi and, more importantly, allows visualization of alternate pathology. In addition, secondary signs are seen that aid in determining obstruction and are helpful if no stone is visualized. Phleboliths, which can simulate a stone, are rarely seen in adolescence. We believe UHCT allows for rapid triage and localization of stones and should be recommended as the primary diagnostic modality for the evaluation of adolescents with suspected renal colic.

Adolescent↗
PubMed2001

Calcification in untreated mediastinal Hodgkin's lymphoma.

Calcification is very rarely reported in untreated thoracic lymphoma. However, calcification can occur (although uncommonly) in lymphoma following chemotherapy or radiation, and in areas of scaring or fibrous healing. The authors describe the case of a pregnant woman with a large mediastinal mass that contained calcifications visible on both chest radiography and thoracic computed tomography, which proved to be Hodgkin's lymphoma.

Adult↗
PubMed2001

Deep venous thrombosis with suspected pulmonary embolism: detection with combined CT venography and pulmonary angiography.

PURPOSE: To determine the frequency and location of deep venous thrombosis at computed tomographic (CT) venography after CT pulmonary angiography in a large series of patients clinically suspected of having pulmonary embolism and to compare the accuracy of CT venography with lower-extremity venous sonography. MATERIALS AND METHODS: Venous phase images were acquired from the diaphragm to the upper calves after completion of CT pulmonary angiography in 650 patients (373 women, 277 men; age range, 18-99 years; mean age, 63 years) to determine the presence and location of deep venous thrombosis. Results of CT venography were compared with those of bilateral lower-extremity venous sonography in 308 patients. RESULTS: A total of 116 patients had pulmonary embolism and/or deep venous thrombosis, including 27 patients with pulmonary embolism alone, 31 patients with deep venous thrombosis alone, and 58 patients with both. Among 89 patients with deep venous thrombosis, thrombosis was bilateral in 26, involved the abdominal or pelvic veins in 11, and was isolated to the abdominal or pelvic veins in four. In patients in whom sonographic correlation was available, CT venography had a sensitivity of 97% and a specificity of 100% for femoropopliteal deep venous thrombosis. CONCLUSION: Combined CT venography and pulmonary angiography can accurately depict the femoropopliteal deep veins, permitting concurrent testing for venous thrombosis and pulmonary embolism. CT venography also defines pelvic or abdominal thrombus, which was seen in 17% of patients with deep venous thrombosis.

Adolescent↗
PubMed2001

Combined CT venography and pulmonary angiography: how much venous enhancement is routinely obtained?

OBJECTIVE: Combined CT venography and helical pulmonary angiography is a new diagnostic test that permits radiologists to check both the pulmonary arteries for embolism and the deep veins of the abdomen, pelvis, and legs for thrombosis in a single examination. The purpose of this study was to determine the degree of venous enhancement routinely obtained using this combined CT examination. MATERIALS AND METHODS: We identified all patients at a single institution who, during a 29-month period, had symptoms suggestive of pulmonary embolism and who underwent CT venography and helical pulmonary angiography. The examinations were performed after the patients received a rapid (3--5 mL/sec) IV injection of 150 mL of nonionic contrast medium (240 mg I/mL). CT venography of the abdomen, pelvis, and lower extremities was performed as follows: Beginning 3 min after the start of contrast medium infusion for helical CT pulmonary angiography, 1-cm axial images obtained at 5-cm intervals were acquired from an area ranging from the diaphragm to the calves. Patients who had evidence of deep venous thrombosis on CT scans were excluded from further analysis. The venous portions of the remaining 429 examinations were retrospectively reviewed at a CT console or workstation by one of two radiologists, and Hounsfield unit measurements were recorded from the inferior vena cava as well as from the right and left external or internal iliac, common femoral, superficial femoral, and popliteal veins. A single Hounsfield unit measurement was obtained from the center of each vessel using a region of interest that was approximately half the diameter of the vessel. Mean Hounsfield unit measurements were then calculated for these venous stations. RESULTS: Mean Hounsfield unit measurements at the inferior vena cava and at the right and left external or internal iliac veins were 97, 95, and 95 H, respectively. Mean measurements at the common femoral veins were 95 H for both the right and left; the mean measurements at the superficial femoral veins were 91 H for both the right and left, and those at the popliteal veins were 97 H for the right and 94 H for the left. CONCLUSION: CT venography of the abdomen, pelvis, and lower extremities begun 3 min after the start of contrast medium infusion for helical CT pulmonary angiography routinely produced high mean levels of venous enhancement.

Angiography↗
PubMed2000

Determining the DNA bending angle induced by non-specific high mobility group-1 (HMG-1) proteins: a novel method.

To study the DNA bending induced by non-sequence-specific HMG-1 domain proteins, we have engineered a fusion protein linking the yeast NHP6A with a sequence-specific DNA binding domain, the DNA binding domain of the Hin recombinase, Hin-DBD. A series of biochemical experiments were carried out to characterize the DNA binding property of this fusion protein. Our data showed that the fusion protein not only specifically recognizes a DNA fragment containing the Hin-DBD binding site, but also binds DNA with a higher affinity in comparison with either domain alone. Both domains of the fusion protein are bound to the DNA in juxtaposition. Permutation assays showed that the fusion protein induced a DNA bending at the site of NHP6A binding by an estimated value of 63 degrees. We believe that this experimental design provides an effective vehicle to determine the DNA bending induced by nonspecific HMG-1 proteins.

Biosensing Techniques↗
PubMed2000

Alternative or additional diagnoses on unenhanced helical computed tomography for suspected renal colic: experience with 1000 consecutive examinations.

OBJECTIVES: To determine the incidence and spectrum of significant alternative or additional diagnoses established or suggested on unenhanced helical computed tomography (CT) in a large series of patients with suspected renal colic. METHODS: One thousand consecutive unenhanced helical CT examinations were performed for suspected renal colic. All official CT reports were retrospectively reviewed, which was followed by review of all available relevant follow-up radiology reports. A selected image and chart review was also performed. RESULTS: Ureteral calculi were identified on 557 examinations, findings consistent with a recently passed stone were discovered on 67 examinations, and 275 CT examinations were unremarkable. An alternative or additional diagnosis was established or suggested on 101 examinations, including in 26 patients with concurrent ureteral calculi. There were 62 genitourinary and 39 nongenitourinary tract diagnoses. Eighty-seven of the diagnoses could be confirmed on retrospective image review combined with patient follow-up. There were two false-positive diagnoses for significant, alternative pathologic findings. CONCLUSIONS: A wide spectrum of significant, alternative, and additional genitourinary and nongenitourinary diagnoses can be reliably established or suggested on unenhanced helical CT performed for suspected renal colic. These abnormalities were identified in 10% of cases in this series of 1000 consecutive CT examinations.

Adult↗
PubMed2000

Extra-thoracic findings on the venous phase of combined computed tomographic venography and pulmonary angiography.

A growing consensus is that pulmonary embolism and thrombosis represent different aspects of the same disease, and a single study that accurately defines both pulmonary emboli and deep venous thrombosis would be a desirable examination. The purpose of this pictorial review is to demonstrate the extra-thoracic findings on the venous phase of such a study, which combines computed tomographic venography and pulmonary angiography.

Aged↗
PubMed2000

Combined CT venography and pulmonary angiography in suspected thromboembolic disease: diagnostic accuracy for deep venous evaluation.

OBJECTIVE: Combined CT venography and pulmonary angiography is a new diagnostic test that evaluates both pulmonary embolism and deep venous thrombosis (DVT) in a single study. Our purpose was to compare the CT venous findings with lower extremity venous sonography. SUBJECTS AND METHODS: Seventy-one consecutive patients with suspected pulmonary embolism underwent helical CT pulmonary angiography during rapid i.v. infusion of contrast medium. Axial scans at 5-cm intervals from the patient's upper calves to the diaphragm were generated 3.5 min after the beginning of contrast medium injection. CT venous phase images were interpreted prospectively and compared with subsequent bilateral lower extremity venous sonography performed within 12 hr. RESULTS: DVT was revealed by CT venous phase images in 19 patients, 12 of whom also had pulmonary embolism. CT and sonographic findings correlated exactly in the femoropopliteal deep venous system, where most pulmonary emboli originate. CT venous phase images also revealed pelvic extension of DVT in six patients and isolated vena cava thrombus in one patient. CONCLUSION: CT venous phase imaging at the time of CT pulmonary angiography is comparable with venous sonography in the evaluation of femoropopliteal DVT. The iliac veins and vena cava, vessels poorly shown on sonography but sometimes the source of significant pulmonary emboli, are also depicted by CT venography.

Adult↗
PubMed1999

Differentiation of hepatic malignancies from hemangiomas and cysts by T2 relaxation times: early experience with multiply refocused four-echo imaging at 1.5 T.

The purpose of this study was to examine hepatic lesions with a sequence designed to yield improved T2 measurements and evaluate the clinical utility of these measurements in distinguishing malignant from benign disease. Using a modified Carr-Purcell sequence incorporating features designed to compensate for imperfections in the imaging system, including a train of refocusing pulses emitted in an MLEV pattern oriented in composite fashion along all three coordinate axes, and a single spatially selective pulse placed immediately before a spiral readout, 14 benign lesions and 13 malignant lesions were evaluated prospectively with a conventional 1.5 T imager. The maximum, minimum, and mean T2 values of malignant lesions, hemangiomas, and cysts exceeded corresponding published values from spin-echo and echoplanar studies. The mean T2 value of the malignant lesions differed significantly (P < 0.0001) from those of hemangiomas and cysts. All malignant lesions and all benign lesions were distinguishable by their T2 values, which had ranges of no greater than 118.6 msec and no less than 134.3 msec, respectively. This early experience suggests that improved T2 measurements can facilitate the differentiation of hepatic malignancies from hemangiomas and cysts.

Carcinoma, Hepatocellular↗
PubMed1999

Detection and follow-up of important extra-arterial lesions with helical CT angiography.

AIM: To determine the prevalence and significance of extra-arterial findings detected prospectively on helical computed tomographic angiography (CTA). SUBJECTS AND METHODS: The official reports of 802 consecutive CTAs performed over a 4.5-year period on 624 patients and the reports of all radiographic follow-up studies were reviewed for identification of important extra-arterial findings. Medical records and imaging studies of all patients with previously unknown extra-arterial findings on CTA were reviewed to assess follow-up. In cases where follow-up was not indicated in the medical record, referring physicians were contacted directly. RESULTS: Important, previously unknown, extra-arterial findings were detected on 35 CTAs (4.4% of all CTAs, 5.6% of all patients), with 33 of 35 detected prospectively. Six lesions were consistent with and/or proven to be malignant. Important non-tumoural lesions were discovered on nine CTAs. Of 13 lesions with imaging features that were suspicious for malignancy. Five of these lesions proved to be benign, but radiographic and/or clinical follow-up was not obtained or could not be documented in eight patients. CONCLUSION: With the increasing use of CTA as a replacement for conventional angiography, careful attention should be paid to the visualized extra-arterial structures. Extra-vascular findings that are believed to be significant, may not be adequately followed-up by referring vascular specialists.

Aged↗
PubMed1999

Radiology of pneumonia.

Chest radiography is the imaging technique of choice in evaluating patients with suspected pneumonia because of its low radiation dose, low cost, and wide accessibility. In daily practice, radiographs are used to confirm the clinical diagnosis of pneumonia, characterize the extent and severity of disease, search for complications such as empyema, monitor the response to therapy, and examine for possible alternative or additional diagnoses. Although CT scan has no defined role in the routine assessment of patients with either community-acquired or nosocomial pneumonias, its advantages of superior contrast resolution and cross-sectional display can often be helpful in the analysis of complex cases, particularly when radiographic evidence of associated central obstruction, cavitation, lymphadenopathy, or empyema is equivocal. In the immunocompromised patient population, high-resolution CT has been shown to be more sensitive than plain film radiography in the early detection of pulmonary infections.

Adult↗
PubMed1999

Unenhanced CT of abdominal and pelvic hemorrhage.

CT performed without oral or intravenous contrast is the initial imaging study of choice in many situations for the detection of hemorrhage anywhere in the abdomen and pelvis. The presence or absence of hemorrhage can be determined rapidly, and the amount and precise location of hemorrhage can also be evaluated. This article reviews the appearances and the common and unusual etiologies of abdominal and pelvic hemorrhage on unenhanced CT. The role of intravenous contrast-enhanced CT in patients with known or suspected abdominal and pelvic hemorrhage is also examined.

Abdomen↗
PubMed1999

Suspected acute appendicitis: nonenhanced helical CT in 300 consecutive patients.

PURPOSE: To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis. MATERIALS AND METHODS: Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both. RESULTS: There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%. CONCLUSION: Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.

Acute Disease↗