Scan length optimization for pulmonary embolism at CT angiography: analysis based on the three-dimensional spatial distribution of 370 emboli in 100 patients.

AIM: To determine the size and three-dimensional spatial distribution of pulmonary emboli (PE) at computed tomography angiography (CTA) to optimize the scan length. MATERIALS AND METHODS: Two experienced radiologists jointly reviewed 100 consecutive, positive PE CTA studies performed in the Emergency Department (53 women; age 61±17 years). All studies were conducted on a 16-detector row CT machine. In each case, the number of emboli was counted and the proximal and distal spatial coordinates of each embolus documented. Coordinates of the main pulmonary artery bifurcation (MPAb) and carina were recorded. For normalization, the thoracic cavity height (H)-from inlet to lowest hemidiaphragm-was measured. The minimal scan lengths for (a) capturing all emboli and (b) rendering a positive diagnosis were determined. RESULTS: Three hundred and seventy (370) emboli were detected. The average number of PE per patient was 3.7 (maximum 12, minimum 1). Their average length was 2.7 cm. Nine patients had saddle emboli (9%), and 71% of emboli were at or below the MPAb. An 18 cm (0.90×H) scan length, centred 4 cm (0.18×H) below the carina, captures all PE in this dataset while reducing z-axis coverage by 29% (34% for normalized data). Moreover, a 14.2 cm (0.78×H) scan length appropriately centred captures at least one embolus in all patients while reducing coverage by 44% (43%). Decreasing scan length to the lesser of 14.2 cm and 0.78×H per patient reduces coverage by 47%. CONCLUSION: Scan length at CTA for PE can be reduced by up to 47% while preserving diagnostic accuracy for PE detection.

Postcatheterization pseudoaneurysms: new developments in the diagnosis and treatment with ultrasound.

Postcatheterization pseudoaneurysms are an increasingly common complication of endovascular procedures. Ultrasound (US) is essential in diagnosis and in playing the key role in the noninvasive treatment of such pseudoaneurysms. The past decade has seen a shift from surgical management to US-guided therapy initially using manual compression. Recently, the minimally invasive technique of percutaneous thrombin injection has been described as an alternative to US-guided compression. This review article discusses the cause and natural history of pseudoaneurysms and describes the technique of US-guided thrombin injection.

Pre-operative localization of parathyroid adenomas: a comparison of power and colour Doppler ultrasonography with nuclear medicine scintigraphy.

AIM: To compare power and colour Doppler ultrasonography (US) with nuclear medicine scintigraphy (NM) in the preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism (PHPT). MATERIALS AND METHODS: Thirty-one patients with biochemical evidence of PHPT underwent pre-operative US and NM for parathyroid adenoma localization. Both studies were interpreted independently without prior knowledge of the other study's findings. All patients had surgical removal of the parathyroid adenoma utilizing standard neck exploration or minimally invasive unilateral surgical techniques with rapid serum assay of circulating parathyroid hormone levels. RESULTS: All patients had single parathyroid adenomas at surgery. Prospective sensitivities for US, NM and both studies combined were 65%, 68%, and 74%, respectively, with a positive predictive value of 100% each. The adenoma was localized by only one imaging modality in 16% of cases. CONCLUSIONS: US and NM provide complementary roles in the pre-operative localization of parathyroid adenomas in patients with PHPT.

Percutaneous injection of thrombin for the treatment of pseudoaneurysms after catheterization: an alternative to sonographically guided compression.

OBJECTIVE: The purpose of our study was to determine the efficacy of percutaneous thrombin treatment for iatrogenic pseudoaneurysms of the femoral artery in comparison with sonographically guided compression repair. SUBJECTS AND METHODS: Twenty-three pseudoaneurysms occurring after catheterization were treated percutaneously with an initial injection of 1.0 mL of thrombin solution via a 22-gauge spinal needle under continuous sonographic guidance. Four patients required the additional injection of 1.0-4.0 mL of thrombin for complete thrombosis. Repeated sonography was performed 24 hr after injection. Additionally, we compared our results with those of a control group by reviewing the imaging findings and medical records of 16 patients who underwent sonographically guided compression of iatrogenic pseudoaneurysms between January 1998 and July 1998. RESULTS: Twenty-two of 23 pseudoaneurysms occurring after catheterization were successfully treated with percutaneous thrombin injection. One recurrence was identified 24 hr after injection in a patient who experienced a significant complication. Procedure time was limited to 15 min with an overall success rate of 96%. Retrospectively, 18 iatrogenic pseudoaneurysms were identified in 16 patients. Six (60%) of 10 pseudoaneurysms were successfully compressed under sonographic guidance, with an average time to thrombosis of 32 min. Compression was unsuccessful for four pseudoaneurysms with an average compression time of 45 min. Compression could not be performed in seven patients (39%). The overall success rate of sonographically guided repair was 60%. CONCLUSION: Preliminary evidence suggests that sonographically guided percutaneous thrombin injection is a safe and effective method of treatment for iatrogenic pseudoaneurysms and offers significant advantages over conventional sonographically guided compression.

Optimal management strategy for use of compression US for deep venous thrombosis in symptomatic patients: a cost-effectiveness analysis.

RATIONALE AND OBJECTIVES: The authors' purpose was to identify the optimal strategy for using compression ultrasonography (US) in patients suspected of having deep venous thrombosis (DVT). MATERIALS AND METHODS: The authors developed a decision-analytic model representing the natural history of DVT and the benefits and risks of anticoagulation therapy. They evaluated six initial imaging strategies: (a) unilateral examination of the common femoral and popliteal veins; (b) unilateral examination of the common femoral, popliteal, and femoral veins; (c) bilateral examination of the common femoral and popliteal veins; (d) bilateral examination of the common femoral, popliteal, and femoral veins; (e) complete unilateral examination of the symptomatic leg (including calf veins); and (f) complete bilateral examination of both legs. RESULTS: For 65-year-old men with unilateral symptoms of DVT, the most effective strategy was bilateral examination of the common femoral and popliteal veins with anticoagulation therapy in patients with proximal DVT and follow-up bilateral examination of the common femoral and popliteal veins in patients without an initial diagnosis of DVT with an incremental cost-effectiveness ratio of $39,000 per quality-adjusted life year gained. CONCLUSION: These results suggest that bilateral examination limited to the common femoral and popliteal veins, with follow-up bilateral examination limited to the common femoral and popliteal veins, was as cost-effective as other well-accepted medical interventions. The results were sensitive to the distribution of clot, diagnostic accuracy of compression US, and probability of bleeding with long-term morbidity.

Color and power Doppler sonography of liver hemangiomas: a dream unfulfilled?

PURPOSE: The aim of this study was to determine whether color Doppler or power Doppler sonography can aid in the diagnosis of hepatic cavernous hemangiomas. METHODS: We imaged 25 hepatic cavernous hemangiomas in 17 patients with gray-scale, color Doppler, and power Doppler sonography. Five malignant lesions were also imaged in the same manner for reference. Hemangiomas had been previously diagnosed by biopsy in 8 patients (15 lesions) and by CT, MRI, and/or tagged red blood cell scanning in 9 patients (10 lesions). RESULTS: Of the 25 hemangiomas, color or power Doppler imaging showed no internal blood flow in 23. Of these 23 lesions, 11 showed a peripheral flow pattern believed to represent flow in displaced blood vessels. This pattern was better visualized with power Doppler imaging in 3 lesions and equally well visualized with color and power Doppler imaging in 8 lesions. Two hemangiomas that had unusual central fibrosis with large vessels in 1 patient showed diffusely increased blood flow on power Doppler study. All 5 malignant lesions showed flow in peripheral vessels, and 1 showed internal vascularity as well. CONCLUSIONS: Neither color nor power Doppler imaging improved the capability of sonography for making a specific diagnosis of benign hepatic cavernous hemangioma.

Detecting hepatic lesions: the added utility of CT liver window settings.

PURPOSE: To prospectively evaluate the utility of adding computed tomographic (CT) liver windows to conventional soft-tissue windows for the detection of hepatic disease. MATERIALS AND METHODS: One of four radiologists experienced in abdominal imaging interpreted 1,175 consecutive abdominal CT scans from one institution. Hepatic images were first interpreted by using standard soft-tissue windows. The number of lesions and confidence in lesion detection were recorded. The liver-window images were then interpreted in conjunction with the soft-tissue-window images, and the number of lesions and confidence in detection were recorded again. The proportion of patients in whom additional lesions were found by using liver windows was determined. RESULTS: On soft-tissue-window and liver-window scans interpreted together, 869 (74%) patients had no hepatic lesions. Thirty-six (3.1%) patients had new lesions seen with the addition of liver windows. Twelve of these 36 patients had no lesions seen on soft-tissue-window scans. Twenty-six of the 36 patients with additional lesions seen had a history of neoplasm. There was a change in diagnosis in 1.7% of the patients with the addition of liver windows and a change in recommendation for follow-up in 0.85%. CONCLUSION: Routine interpretation of liver-window scans for all abdominal CT scans has limited added utility in detecting hepatic disease.

Percutaneous biopsy in diffuse renal disease: comparison of 18- and 14-gauge automated biopsy devices.

PURPOSE: To compare 18-gauge-needle automated biopsy guns to 14-gauge systems for diagnostic efficacy and safety in percutaneous renal biopsy. MATERIALS AND METHODS: One hundred sixty-one computed tomographic (CT) guided biopsies for diffuse renal disease were retrospectively reviewed. An automated biopsy gun with an 18-gauge needle was used in 74 procedures, and a 14-gauge needle was used in 87 cases. RESULTS: Adequate tissue for histologic diagnosis was obtained in 96% (71 of 74) of cases with use of the 18-gauge needle, compared with 99% (86 of 87) in the 14-gauge group. The mean glomeruli per specimen were 10.7 and 13.7, respectively. Major hemorrhagic complications occurred in two cases (2.7%) of the 18-gauge group and in three cases (3.4%) of the 14-gauge group. CONCLUSION: The use of a biopsy gun with an 18-gauge needle provides high tissue recovery rate, comparable to that with the 14-gauge system. The complication rate was acceptably low, with no statistically significant difference from the 14-gauge needles (P = .80).

Acute urinary tract obstruction. Imaging update.

Although urinary tract obstruction is an age old problem with IVU the time-honored imaging technique of choice, recent advances in renal ultrasonography and abdominal and pelvic CT scanning have advanced these alternative modalities to the forefront. No rigid algorithm for renal obstruction is recommended, because the utilization of these techniques is in a state of flux. The use of one modality over another as a first-line imaging technique likely will depend on the equipment availability and expertise of a given institution. The choice also may be guided by each institution's cost of each type of examination. Although a role for the IVU remains in the evaluation of acute renal obstruction, ultrasonography and CT scan have emerged as alternative primary screening tools. Undoubtedly, the future will bring further changes in our assessment of renal obstruction. The cost effectiveness and definitiveness of evaluation likely will become more important driving factors than they have been in the past. The radiologist and urologist together must assess available imaging techniques, their effectiveness, and the institution's expertise to develop a cost-effective and efficient system for assessment of renal obstruction.

Controversies in venous ultrasound.

Ultrasound is the principal method used for diagnosing deep venous thrombosis in the United States, and its accuracy and limitations are well known. As venous ultrasound examination has matured, several controversial issues, primarily clinical, have arisen concerning the application of this diagnostic method. This article addresses some of the more noteworthy and vexing issues, including, but not limited to (a) the need to examine both legs in patients with unilateral symptoms; (b) the role of venous ultrasound in patients with bilateral leg swelling; (c) the necessary extent of the venous ultrasound examination; (d) the importance of calf vein thrombosis; (e) the significance of negative leg veins in a patient with possible pulmonary embolus; and (f) deep venous thrombosis in patients with occult malignancy. Technical aspects of the venous ultrasound examination, and diagnostic accuracy are not described.

Percutaneous biopsy.

This article reviews various percutaneous biopsy techniques of the kidney, adrenal gland, retroperitoneum, and prostate gland, with emphasis on appropriate indications and technical performance. Variations in biopsy techniques are numerous and preservation of patient safety and successful recovery of tissue are parameters of success.

Use of computed tomography scanning before and after sitting in an emergency department.

RATIONALE AND OBJECTIVES: Before a computed tomography (CT) scanner was installed in the emergency department, this hospital had no dedicated CT scanner for patients in the emergency department, and transporting these patients to the CT scanners in the radiology department took approximately 8-10 min each way. We sought to determine whether the presence of a CT scanner within the emergency department would lead to an increase in the number of emergent cranial CT examinations and a decrease in the diagnostic yield of these examinations. METHODS: More than 8,000 records of cranial CT examinations were reviewed for the 12 months before and the 12 months after the installation of the CT scanner in the emergency department. A positive case was defined as one that showed acute abnormality such as ischemia, hemorrhage, edema, or mass effect. RESULTS: Our results show a 30.1% increase in the number of CT scans of the head ordered by physicians in the emergency department after the installation of a CT scanner (p < .0001). This is compared with the background 1.8% increase in the total number of emergency department visits. However, in both periods, 12% of the total number of head scans done were positive. CONCLUSION: The convenience of having a CT scanner in the emergency department leads to greater use of CT examinations. However, the increase in the number of emergent CT studies is justified because the number of positive CT examinations increases proportionately.

Symptomatic deep vein thrombosis: diagnosis with limited compression US.

PURPOSE: To evaluate the utility of limited compression ultrasound (US) in the diagnosis of deep vein thrombosis (DVT). MATERIALS AND METHODS: Positive sonograms (n = 160) in 155 symptomatic patients were reviewed retrospectively to assess the distribution of DVT. Fifty-three symptomatic patients underwent 56 limited US examinations of the common femoral and popliteal veins only, followed by traditional US of the entire venous system of the lower extremity from the inguinal ligament to the calf veins. RESULTS: Proximal vein thrombosis was seen in 146 cases (91%); the other 14 cases (9%) showed isolated calf vein thrombosis. In 145 cases (99%), either the common femoral or the popliteal vein was involved. Seven (12%) of 56 examinations showed the presence of thrombosis. Limited examination depicted each case of DVT that was detected with the complete examination, with an average decrease in examination time of 9.7 minutes, or 54%. CONCLUSION: Limited compression US in patients with symptomatic DVT is a viable alternative to routine US; the examination time is decreased by greater than one-half.

Color Doppler sonography: anatomic and physiologic assessment of the thyroid.

The purpose of this study was to assess the potential application of color Doppler sonography in thyroid imaging. Thyroid nodules and other thyroid pathology detected by color Doppler ultrasound and nuclear scintigraphy were compared in 115 patients. The majority of "cold" nodules demonstrated a peripheral rim of color flow and no internal color flow with color Doppler sonography. A large number of "hot" nodules demonstrated internal color flow. Color Doppler sonography was helpful in delineating nodules in otherwise inhomogeneous glands. We determined that color Doppler cannot reliably distinguish benign from malignant thyroid nodules; fine-needle aspiration biopsy remains the most accurate method in differentiating benign and malignant lesions. We suggest that color Doppler sonography plays only a limited role in the evaluation of nodular thyroid disease at this time. The color Doppler appearance of other thyroid disorders (including toxic multinodular goiter, Graves' disease, and thyroiditis) is discussed.