CT imaging of complications of catheter ablation for atrial fibrillation.

The complication rate following radiofrequency catheter ablation for atrial fibrillation is low (<5%). Complications include pericardial effusion, cardiac tamponade, pulmonary vein stenosis, oesophageal ulceration or perforation, atrio-oesophageal fistula formation, stroke/transient ischaemic attack, phrenic nerve injury, haematoma at the puncture site, and femoral arteriovenous fistula. Among available imaging tools, computed tomography (CT) can be very useful in diagnosing complications of the procedure, particularly in the subacute and delayed stages after ablation. This review illustrates CT imaging of several of the common and uncommon complications of radiofrequency catheter ablation.

Benchmarking a novel ultrasound-CT fusion system for respiratory motion management in radiotherapy: assessment of spatio-temporal characteristics and comparison to 4DCT.

Management of respiratory motion during radiation therapy requires treatment planning and simulation using imaging modalities that possess sufficient spatio-temporal accuracy and precision. An investigation into the use of a novel ultrasound (US) imaging system for assessment of respiratory motion is presented, exploiting its good soft tissue contrast and temporal precision. The system dynamically superimposes the appropriate image plane sampled from a reference CT data set with the corresponding US B-mode image. An articulating arm is used for spatial registration. While the focus of the study was to quantify the system's ability to track respiratory motion, certain unique spatial calibration procedures were devised that render the software potentially valuable to the general research community. These include direct access to all transformation matrix elements and image scaling factors, a manual latency correction function, and a three-point spatial registration procedure that allows the system to be used in any room possessing a traditional radiotherapy laser localization system. Counter-intuitively, it was discovered that a manual procedure for calibrating certain transformation matrix elements produced superior accuracy to that of an algorithmic Levenberg-Marquardt optimization method. The absolute spatial accuracy was verified by comparing the physical locations of phantom test objects measured using the spatially registered US system, and using data from a 3DCT scan of the phantom as a reference. The spatial accuracy of the display superposition was also tested in a similar manner. The system's dynamic properties were then assessed using three methods. First, the overall system response time was studied using a programmable motion phantom. This included US video update, articulating arm update, CT data set resampling, and image display. The next investigation verified the system's ability to measure the range of motion of a moving anatomical test phantom that possessed both high and low contrast test objects. Finally, the system's performance was compared to that of a four-dimensional CT (4DCT) data set. The absolute spatial and display superposition accuracy was found to be better than 2 mm and typically 1 mm. Overall dynamic system response was adequate to produce a mean relative positional error of less than 1 mm if an empiric latency correction of 3 video frames was incorporated. The dynamic CT/US display mode was able to assess phantom motion for both high and low contrast test objects to within 1 mm, and compared favorably to the 4DCT data. The 4DCT movie loop accurately assessed the target motion for both of the high and low contrast objects tested, but the minimum intensity and average intensity reconstructions did not. This investigation demonstrated that this US system possesses sufficient spatio-temporal accuracy to properly assess respiratory motion. Future work will seek to demonstrate efficacy in its clinical application to respiratory motion assessment, particularly for sites in the upper abdomen, where low tissue contrast is evident.

Diagnosis of Pneumocystis carinii pneumonia. Roentgenographic-pathologic correlates based on fiberoptic bronchoscopy specimens from patients with the acquired immunodeficiency syndrome.

We analyzed the diagnosis of Pneumocystis carinii pneumonia by fiberoptic bronchoscopy in a large series of patients with the acquired immunodeficiency syndrome (AIDS). Transbronchial biopsy fragments, as opposed to endobronchial specimens, were found to have high diagnostic value. Their optimal number for diagnosis was determined by a simple statistical principle. It varied from a minimum of two in cases of severe pneumonia to a maximum of four when roentgenographic manifestations were altogether absent. The diagnostic yield of the transbronchial biopsy alone was 97 percent and that of "touch" preparations of the biopsies 88 percent; when both techniques were combined, the accuracy rose to 98 percent. By comparison, bronchial "washings" and "brushings" had a much lower yield, 59 percent and 57 percent, respectively. Because their diagnostic contribution was negligible, we conclude that the latter two procedures represent an unnecessary expense and waste of technical and professional effort.

Radiologic-pathologic-clinical correlation in mechanisms of disease course.

The interdisciplinary approach to medical education has often been deficient in medical school curricula. Because of the nonintegrated approach to medical education, problem solving capabilities are not fostered. The clinical presentation of a patient, the imaging modalities used to investigate the patient, and the ultimate pathologic diagnosis are frequently not correlated. At the University of Miami School of Medicine/Jackson Memorial Medical Center, radiology coordinates, along with pathology and the various clinical medicine sections, a Mechanisms of Disease course for sophomore students. This course serves as a "bridge" between the basic sciences (first two years) and the clinical years (last two years). We utilize a Radiologic-Pathologic-Clinical (RPC) correlation approach to problem-solving and algorithms to teach proper problem-solving techniques.

Fundamentals course for 1st-year radiology residents.

RATIONALE AND OBJECTIVES: The authors set out to provide 1st-year residents with basic knowledge to make conferences more useful, to make their knowledge more uniform, and to assess their competency to begin night call. MATERIALS AND METHODS: Faculty taught three afternoon sessions a week in subspecialty areas of radiology, including physics, during the 1st 6 months of residency. Material selected was believed to be essential for the understanding of that subspecialty's didactic lecture series. Emphasis was also placed on diagnoses residents would be expected to make once they began taking night call. Material was presented through lectures, images, and unknown cases. An examination was administered at the end of the course. Residents were allowed to begin night call only after completing the course and passing the final examination. RESULTS: All 1st-year residents completed the course and passed the examination. Their scores ranged from 70% to 83.3%. CONCLUSION: Residents liked the course and reported feeling ready to begin call. Faculty reported the residents who completed the course were more knowledgeable prior to formal rotations than residents from previous years who had not taken the course.

Kaposi sarcoma in a renal transplant patient.

The radiographic abnormalities of primary Kaposi's sarcoma of the lung in a patient with a renal transplant are reported. The findings are similar to other malignancies and infections that are well recognized in the renal transplant population. In the appropriate clinical setting, the radiologist should consider the diagnosis of Kaposi's sarcoma even in the absence of cutaneous lesions as reducing immunosuppression can be curative therapy.

The radiology of the thoracic manifestations of AIDS.

The thoracic manifestations of AIDS have undergone a gradual metamorphosis, partly due to more awareness about the disease leading to earlier diagnoses and partly due to the fact that research has produced more effective prophylaxis as well as treatment for these patients. Many patients now demonstrate partial or complete clinical response which prolongs the length and quality of life of individuals positive for the Human Immunodeficiency Virus (HIV+). Also, with the large number of infected individuals coming to medical attention, and the years of experience in diagnosing and treating these AIDS patients, we now recognize not only the usual but also less usual manifestations of thoracic illnesses in AIDS, including infections, non-infectious diseases such as HIV associated Lymphocytic Interstitial Pneumonia and the neoplasms associated with AIDS. A section will be devoted to HIV infection in children. We will finish the article with a discussion of the current role of Nuclear Medicine in the diagnosis of HIV associated thoracic diseases. These topics are the subject of this article.

HIV-associated lymphocytic interstitial pneumonia: radiologic manifestations and pathologic correlation.

The authors reviewed chest radiographs of 16 patients with biopsy-proved lymphocytic interstitial pneumonia (LIP) who also had acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). Radiographs revealed fine reticular or reticulonodular infiltrates in the pulmonary interstitium in five patients, coarse reticulonodular infiltrates in two, and reticular or reticulonodular opacities with superimposed patchy alveolar infiltrates in nine. Pathologic examination of biopsy specimens revealed lymphocytes, plasma cells, and reticulum cells aggregated about the small arteries and compressing the distal airways. Throughout the course of AIDS or ARC, the radiographic findings of LIP remained stable in 12 of 16 patients. AIDS/ARC-related LIP appears to be a benign reaction of bronchial-associated lymphatic tissue to the human immunodeficiency virus (HIV). However, this indolent process cannot be correctly diagnosed based on radiographic findings alone; the use of lung biopsy is required to differentiate LIP from other infections. The authors suggest that patients with these radiographic findings, HIV seropositivity, but no other signs of opportunistic infection or neoplasia should be classified as having AIDS.

Clinical presentation and outcome of patients with HIV infection and tuberculosis caused by multiple-drug-resistant bacilli.

OBJECTIVE: To determine the clinical manifestations of patients with human immunodeficiency virus (HIV) infection and tuberculosis caused by multiple-drug-resistant bacilli compared with those with single-drug-resistant or susceptible bacilli. DESIGN: Descriptive, case-control, and cohort studies. SETTING: A large urban teaching hospital. PATIENTS: Sixty-two patients with tuberculosis caused by multiple-drug-resistant bacilli (cases) and 55 patients with tuberculosis caused by single-drug-resistant or susceptible bacilli (controls). MEASUREMENTS: Characteristics of clinical presentation, radiographs, pathologic abnormalities, antituberculosis treatment, and clinical course. RESULTS: Twenty cases (32%) had concomitant pulmonary and extrapulmonary disease at presentation compared with 9 controls (16%; odds ratio, 2.4; 95% CI, 1.0 to 5.9). More cases had alveolar infiltrates (76%; odds ratio, 3.6; CI, 1.2 to 11.4), interstitial infiltrates with a reticular pattern (67%; odds ratio, 7.8; CI, 1.0 to 83.5), and cavitations (18%; odds ratio, 6.6; CI, 0.8 to 315.3) on initial chest radiographs compared with controls (49%, 19%, and 3%, respectively). Pathologic specimens from cases showed extensive necrosis, poor granuloma formation, marked inflammatory changes with a predominance of neutrophils, and abundant acid-fast bacilli. Twenty-five cases received two or more effective antituberculosis drugs for more than 2 months. Only 2 cases had three consecutive negative cultures for Mycobacterium tuberculosis; one patient died within 1 day of the last negative culture, and the other had positive cultures 496 days later. The remaining 23 cases had persistently or intermittently positive cultures despite therapy. The clinical course of these cases suggested overwhelming miliary tuberculosis with involvement of the lungs (77%), pleura (15%), stool (34%), meninges (13%), bone marrow (16%), blood (10%), lymph nodes (10%), and skin (8%). The median survival time was 2.1 months for cases compared with 14.6 months for controls (P = 0.001, log-rank test). CONCLUSIONS: Tuberculosis caused by multiple-drug-resistant bacilli in patients with HIV infection is associated with widely disseminated disease, poor treatment response with an inability to eradicate the organism, and substantial mortality.