Peter L. Choyke

Pancreatic pseudotumors associated with multifocal idiopathic fibrosclerosis

Two patients with multifocal idiopathic fibrosclerosis and sclerosing cholangitis developed biliary obstruction due to a fibrotic pancreatic pseudotumor. The masslike fibrosis mimicked pancreatic carcinoma on sonography and cholangiopancreatography. In one patient sonography was successfully used to assess the response of the pseudotumor to corticosteroid therapy.

Aortic dissection following coronary artery bypass surgery: Diagnosis by CT

We describe an unusual case of aortic dissection causing spinal cord infarction. The dissection arose from an intimal tear at the suture line of a coronary artery bypass graft. CT was used to diagnose the dissection and to demonstrate its extension to the aortoiliac bifurcation and innominate artery and its rupture into the left pleural cavity. The most common causes of intimal tears following cardiac bypass surgery are aortic cross-clamping, aortic cannulation, and injury during suturing of the graft to the aorta. An underlying disease of the aorta such as atherosclerosis, cystic medial necrosis, or aortitis is commonly present. CT is an accurate and safe means of detecting aortic dissections following cardiac surgery, and is also useful in assessing the extent of the dissection and identifying its rupture into the pleural or pericardial cavity.

Scrotal enlargement following inguinal herniorrhaphy: Ultrasound evaluation

Although sonography has become an established modality in the evaluation of acute and chronic scrotal abnormalities, its role in the post-herniorrhaphy patient with scrotal swelling has not yet been defined. We present 5 patients with immediate and delayed complications of herniorrhaphy in which sonography provided useful clinical information. Immediate complications included scrotal hematomas, scrotal wall and septal thickening, epididymitis, and testicular displacement. Delayed complications included an infected hydrocele demonstrating a fluid-debris level. The etiology of scrotal swelling in postherniorrhaphy patients can be determined with sonography.

Invasion of the inferior vena cava by testicular seminoma: Demonstration by computed tomography and venography

Involvement of the inferior vena cava (IVC) by testicular neoplasms is unusual and often clinically unsuspected. We present a patient with testicular seminoma that involved the IVC secondarily and caused multiple pulmonary emboli requiring the placement of a caval filter. The radiographic features of this phenomenon are presented with special emphasis on the computed tomographic (CT) appearance of caval thrombosis and pulmonary embolus. The characteristically low density lymphadenopathy of seminoma may obscure the diagnosis of caval thrombosis on CT. Although the findings are nonspecific, tumor invasion of the IVC should be suspected in all patients with testicular neoplasms who demonstrate caval thrombosis radiographically.

Prevesical hematoma: A complication of prostatic biopsy

Pelvic hematomas following prostatic biopsy are rare. We describe 2 cases of hematomas occurring in the prevesical space (space of Retzius) following transrectal biopsy. Computed tomography (CT) was useful in defining the extent of the hematoma and showing density changes related to the age and suppuration of the hematoma. While cystography has been used to diagnose prevesical hematomas, CT better assesses the size of the hematoma and changes that may occur over time.

Duplex Sonography of the Abdomen

Duplex sonography, which integrates real-time imaging with pulsed-Doppler analysis, has greatly expanded the diagnostic capabilities of conventional ultrasound examinations. Within the abdomen, several applications have been established and, through clinical research, new indications are being defined. Information regarding blood flow is obtained by placing a sample volume within a desired location and detecting the backscattered sound beam (1). After processing of the Doppler shift signals, the data is then available both as an audible output and as a graphical display, with Doppler frequency shift (or velocity) on the vertical axis versus time on the horizontal axis. The configuration of the waveform reflects the status of the proximal circulation as well as the receiving vascular bed. Specific parameters that determine waveform shape include cardiac contractility, vascular wall compliance, luminal diameter, velocity of blood flow, presence or absence of turbulence, and downstream vascular resistance (2). These, in turn, are affected by other factors such as the individual’s physiologic status. Notable examples include altered circulatory impedance of the distal aorta and lower extremities between resting and postexercise states, as well as variation in superior mesenteric arterial flow between fasting and postprandial states.

Reliability Issues In Digital Image Archiving

Reliability issues are of prime concern in the design of a digital archive. We investigated the current archiving system to determine how reliable it was and what impact this had clinically. Although the digital archive will significantly improve the reliability of archiving, subsystem failures may negatively impact function. Scenarios are presented to identify potential problems with and solutions to subsystem failures of the digital archive.

Imaging of the Liver, Biliary Tract, and Pancreas

The interaction between the various noninvasive and invasive imaging modalities used to evaluate the liver, biliary tract, and pancreas is demonstrated in this article. By understanding this interaction and correlating noninvasive studies, the clinician will avoid diagnostic redundancy and the need for invasive testing may be reduced.

Design and Implementation of PACS at Georgetown University Hospital

During the preparation and planning phase of the PACS project at Georgetown University Hospital it was realized that PACS requires truly the state of the art technology in data communication, image processing and man machine interfacing. It was also realized that un-like many other technology intensive devices used in radiology, PACS cannot be seen as an independent system that will provide well defined services. PACS will be the backbone of the department operation in clinical, educational and managerial functions. It will indeed be the nerve center of the radiologic services affecting every aspect of the department. PACS will have to be designed to perform in a cost-effective manner to widely varying needs within the radiology departments. The integration of ever changing complex technology that will impact every aspect of a radiology service is not a trivial matter. This transition period going from current manual film based PACS to Digital PACS can be long, expansive and disruptive unless careful planning preceeds the implementation. PACS is still an emerging technology at its infancy. Performance monitoring and evaluation of diversified functions have to be also established so that improvement to the system can be efficiently implemented. Thus the evaluation criteria should be also established as early as possible.

Imaging of Urinary Tract Disease: Current Approaches

Current modalities and techniques used in imaging of the urinary tract offer prompt and accurate diagnoses as well as treatment in some cases. Careful planning and judgement in the choice of the imaging sequence is important in avoiding redundant or ill-advised tests. Individual tailoring will be necessary in some patients. It is hoped that with the rational use of the diagnostic tools now available and with the continued improvement in MRI technology, safe and accurate diagnoses will be expected in practically all patients with diseases of the urinary tract.