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.

Renal mass imaging: the internist's role.

The busy internist will encounter numerous renal masses when ordering nonurologic imaging. Concise and quick delineation of cystic from solid masses is necessary. Cystic masses constitute the majority of these masses and once their nature is diagnosed, they require no further work-up or referral. Often, a single imaging technique is unable to confidently establish the cystic nature of a renal mass. Proper selection of an additional imaging modality will often be successful in establishing the cystic characteristics of a benign mass. Referral to a urologist is not necessary in this setting, since the internist can coordinate the imaging evaluation with proper radiologic consultation. Alternatively, when a mass is determined to be solid, urologic consultation and surgical evaluation are necessary. Minimization of the imaging sequence and hospitalization are critical in the diagnostic-related group era. Aimless wandering in the quagmire of imaging techniques is very expensive and nonproductive. Proper selection of one or two imaging tools and occasionally needle puncture should produce clarification of the cystic or solid nature of renal mass. On the basis of our experience, we have designed an imaging algorithm that provides a simple and concise approach to the diagnosis of a renal mass. It differs in design from that previously suggested by us and others because of decreased emphasis on nuclear medicine and greater emphasis on computed tomography. The more pivotal position assumed by computed tomography is based on improved scanner design and several large series attesting to the accuracy and cost-effectiveness of this imaging technique. It behooves internists to appreciate the role of various imaging tools in evaluating a renal mass. With radiologic consultation, internists should strive to confidently establish the cystic nature of a renal mass and to refer to a urologist solid masses or those whose nature remains persistently equivocal.

Renal parenchymal malakoplakia. Histologic spectrum and its relationship to megalocytic interstitial nephritis and xanthogranulomatous pyelonephritis.

We report five cases of renal parenchymal malakoplakia. They represent a histologic spectrum of this uncommon inflammatory process as it involves the renal parenchyma. Only one of these five cases presented the classical histologic picture of malakoplakia ("diagnostic stage"). Two cases--although with similar cellular infiltrate--had a marked paucity of Michaelis-Gutmann bodies and thus might have been classified as megalocytic interstitial nephritis were it not for the identification of such calcific intracellular inclusions under the electron microscope. The fourth case presented a pseudosarcomatous morphology and is similar to what has been described as a late or fibrous stage in malakoplakia of the urinary bladder. The last case had a destructive, frankly granulomatous histologic picture with a preponderance of foamy histiocytes reminiscent of xanthogranulomatous pyelonephritis, but with clusters of von Kossa-positive Michaelis-Gutmann bodies. The last two forms of the disease have not been previously reported to occur in the kidney. We believe that these cases represent various stages of development of the disease.

Pediatric abdominal trauma: evaluation by computed tomography.

When indications for immediate laparotomy are not present, CT of the abdomen and pelvis can be used to evaluate pediatric blunt abdominal trauma. During 2-year period, the medical records and abdominal/pelvic CT scans of 100 consecutive pediatric patients who were evaluated for blunt abdominal trauma were retrospectively reviewed. The scans appeared normal for 73 children. Of these children, 30 had severe head injuries and a depressed sensorium. A total of 27 abdominal/pelvic CT scans were interpreted as abnormal. Findings included nine splenic fractures, six renal contusions, nine hepatic lacerations, one duodenal hematoma, one traumatic pancreatitis, four bony injuries, six miscellaneous abnormalities, and one intraperitoneal bleed. Only two of these 27 patients required abdominal surgery. The remaining 25 patients were treated conservatively based upon a stable clinical state and CT delineation of the extent of injury. No mortality resulted. CT is the radiographic examination of choice for hemodynamically stable pediatric patients with blunt abdominal trauma. CT provided a reliable adjunct examination technique when a physical examination could not be performed and a complete history could not be obtained. The extent of abdominal/pelvic injuries is well delineated and can often be followed by diagnostic imaging, usually allowing for conservative therapy.

Advances in ultrasound imaging of venous thrombosis.

In the contemporary clinical setting, a diagnosis of deep vein thrombosis can be established using ultrasound. While different ultrasound modalities, including direct B-mode venous imaging, Doppler, and vein compression, have been employed to diagnose clot, it is the compression technique that has been established as the dominant method. In venographically controlled series, compression ultrasound has demonstrated a 93% sensitivity and 99% specificity for clot detection. These remarkable results have been achieved without the evaluation of calf veins. Recent improvements in instrumentation have permitted the direct visualization of calf veins, and it would seem likely that this will result in even better sensitivity for clot detection.

Percutaneous large bore venotomy and tract creation: comparison of sequential dilator and angioplasty balloon methods in a porcine model. Preliminary report.

We used a pig model to evaluate the pathologic changes that occur during large caliber percutaneous venotomy and tract creation such as is necessary to deliver the Greenfield vena caval filter. Four sequential dilator and four angioplasty balloon tract creations were performed on eight external jugular veins in four adult pigs. Gross and microscopic evaluations of the veins and surrounding tissue followed the procedures. Morphometric measurements based on extent and severity of pathologic changes in the specimens were graded from 0 (normal) to 3 (severe and/or extensive). We found that while either technique entailed damage to the veins, the sequential dilator method produced substantially more smooth muscle stretching and tearing and disruption of the internal elastica. There also was greater perivascular and intramural hemorrhage. These changes extended as far distally as the catheters and sheaths were advanced. While the number of experimental samples is too small to allow valid statistical analysis, our results suggest that the angioplasty balloon technique may be superior for tract and venotomy creation. Furthermore, large sheaths should be advanced only enough to maintain venous access to limit the extent of potential venous damage.

Lower moiety hydronephrosis in duplicated kidneys.

Because of the high incidence of lower pole reflux in complete duplications, decreased, delayed, or absent function in a hydronephrotic lower pole moiety is usually initially attributed to reflux nephropathy. Obstruction occurs commonly in the upper pole moiety due to an ectopic ureteral orifice or ureterocele. However, obstruction is not uncommon in the lower pole segment. Here, the etiologies are more numerous and, on occasion, result in confusing presentations. Eleven cases of obstruction involving the lower pole moiety are discussed. Pathologic entities involved include ureteropelvic junction obstructions in both complete and incomplete duplications, calculi and epithelial tumors obstructing the lower system at various levels, and an ectopic upper pole ureterocele compressing and obstructing the ureteral orifice to the lower pole.

Impressions on floor of female bladder: "the female prostate".

The "female prostate" denotes an impression on the base of the female bladder resembling the enlarged male prostate radiographically. Though the finding is widely recognized, confusion exists as to its significance. The differential diagnosis is moderately extensive, and includes retroverted uterus, anterior vaginal tumors, urethral and bladder floor tumors, benign and malignant bony pelvic lesions, urethral diverticulum, and postsurgical changes. Several cases are presented illustrating the previously mentioned causations. An impression on the floor of the female bladder should not be routinely dismissed as inconsequential without thorough evaluation.

Ultrasonic inaccuracies in diagnosing renal obstruction.

Renal ultrasound is an excellent screening examination for suspected urinary tract obstruction. Its usefulness is based on the ability to detect hydronephrosis. However, it must be recognized that a significant number of conditions exist which can mimic or produce dilatation of the collecting system without urinary tract obstruction. Similarly, obstruction without hydronephrosis, although infrequent, exists. Situations causing either false positive or false negative renal sonograms are discussed. Renal sonography suggesting hydronephrosis should be followed with additional diagnostic studies to confirm or exclude obstruction. Similar persistence should be used when obstruction is strongly suggested clinically, and ultrasound fails to demonstrate hydronephrosis.

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.

Contemporary concepts in imaging urinary tract obstruction.

Imaging techniques for renal obstruction remain in a continual state of flux. An improved data base has been developed for renal ultrasonography, permitting a more precise evaluation of hydronephrosis. Rigidity with regard to an algorithm for renal obstruction is not recommended because it would be fixed at a point in time and dependent upon the equipment and expertise of a given institution. In all likelihood ultrasonography will continue to be used as the primary screening tool. A role for the intravenous urogram remains, especially in the acute presentation of renal obstruction. It is interesting to note that the initial description of the percutaneous nephrostomy tube was as a diagnostic technique in patients who had long-standing ureteropelvic junction obstruction. Prediction of recoverability of the kidneys was not possible without relieving the obstruction and assessing the ability of the postobstructive kidney to function. Recoverability of renal function cannot be assessed on a short-term basis but takes time. Up to 8 weeks is necessary before the kidney has established its new baseline level of function. The percutaneous nephrostomy has become an integral tool for the interventional radiologist and is used in treatment. Indeed, its treatment role is important, and even today we must be careful not to assess the kidneys' functional status after placement of the nephrostomy tube without allowing the renal unit sufficient time for recovery. The future undoubtedly will bring further tremendous changes in our assessment of renal obstruction. It is important that radiologists position themselves at the forefront of these developments.

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.

Venous ultrasonography.

Compression ultrasonography supplemented by pulsed and color Doppler imaging is the diagnostic modality of choice for evaluating lower extremity deep vein thrombosis in symptomatic and asymptomatic high-risk patients. Furthermore, this technique frequently can characterize the clot as occlusive or nonocclusive or acute or chronic and can define the extent of disease. In patients without thrombosis, this modality can suggest an alternative diagnosis in 12% of patients.

Imaging approach to the suspected renal mass.

The authors present their algorithmic approach to the detection, characterization, and staging of renal masses. Based on classification of urographic findings, the patient may be triaged to the appropriate cross-sectional or invasive imaging modality that will result in the most cost-effective management.

Compression ultrasonography for the detection of deep venous thrombosis in patients who have a fracture of the hip. A prospective study.

The effectiveness of compression ultrasonography in the detection of femoral and popliteal venous thrombosis was determined in a prospective trial over a period of seven months. Forty-two patients who had an isolated intertrochanteric or femoral neck fracture participated, and forty of these patients completed the study. The average age of the patients was 81.6 years. Venography was the standard with which all ultrasonic studies were compared. A total of 112 ultrasonic studies were performed. The incidence of major venous thrombosis, as detected by venography, was 12.5 per cent. All patients were clinically asymptomatic. The compression ultrasonic technique had an accuracy of 97 per cent, a sensitivity of 100 per cent, and a specificity of 97 per cent. Compression ultrasonography appears to be a very effective technique for diagnosing venous thrombosis in patients who have a fracture of the hip. It is safe, well accepted by both patients and staff, and simply and quickly performed, and it carries no inherent risks. It also can be readily repeated, making it ideal for monitoring high-risk patients.

Percutaneous alternatives in nutritional support: a radiologic perspective.

As alternatives to per os feeding and nutritional support increase in number and complexity, the interventional radiologist has come to play a more significant role in the creation and maintenance of nutritional access. In very difficult access cases, the concerted effort of the nutritional surgeon and the radiologist is often required. We describe several such situations which have been successfully managed at our institution. The indications for and techniques of percutaneous reestablishment of surgically placed jejunostomy tubes, the percutaneous conversion of gastrostomy to jejunostomy tubes with retention of the gastrostomy tube, and percutaneous placement of an inferior vena caval Hickman catheter are all described in detail.

Vascular ultrasound in the intensive care unit.

Ultrasonography plays an increasingly important role in the evaluation of the vascular system. It is especially useful for the intensive care patient because of its ability to be performed at the patient's bedside, as well as the relatively high frequency of vascular complications in the ICU. Ultrasonography is the method of choice for evaluation of deep vein thromboembolic disease of the lower extremity in all patients, demonstrating excellent sensitivity and specificity for this condition. It also should be the initial method of evaluating upper extremity deep vein thrombosis. It may be limited in this assessment, however, because it does not reliably demonstrate the central subclavian and innominate veins, and therefore may be inadequate for evaluation of malfunctioning central venous catheters. Ultrasonography can reliably identify the presence of abdominal aortic aneurysms, although computed tomography is better able to demonstrate location and extent of these lesions. Finally, ultrasonography can be used to diagnose complications of arterial catheterization and, in selected patients, may direct compression of pseudoaneurysms, resulting in thrombosis and thereby averting surgical repair.

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.

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.

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.