Imaging of suspected pulmonary embolism and deep venous thrombosis in obese patients
Obesity is a growing problem around the world, and radiology departments frequently encounter difficulties related to large patient size. Diagnosis and management of suspected venous thromboembolism, in particular deep venous thrombosis (DVT) and pulmonary embolism (PE), are challenging even in some lean patients, and can become even more complicated in the setting of obesity. Many obstacles must be overcome to obtain imaging examinations in obese patients with suspected PE and/or DVT, and to ensure that these examinations are of sufficient quality to diagnose or exclude thromboembolic disease, or to establish an alternative diagnosis. Equipment limitations and technical issues both need to be acknowledged and addressed. Table weight limits and scanner sizes that readily accommodate obese and even morbidly obese patients are not in place at many clinical sites. There are also issues with image quality, which can be substantially compromised. We discuss current understanding of the effects of patient size on imaging in general and, more specifically, on the imaging modalities used for the diagnosis and treatment of DVT and PE. Emphasis will be placed on the technical parameters and protocol nuances, including contrast dosing, which are necessary to refine and optimize images for the diagnosis of DVT and PE in obese patients, while remaining cognizant of radiation exposure. More research is necessary to develop consistent high-level evidence regarding protocols to guide radiologists, and to help them effectively utilize emerging technology.
Multi-modality imaging of the leaking ureter: why does detection of traumatic and iatrogenic ureteral injuries remain a challenge?
Ureteral injuries are uncommon in trauma patients, accounting for fewer than 1% of all injuries to the urinary tract. These uncommon, yet problematic, injuries can often be overlooked in the standard search pattern on abdominal and pelvic multi-detector CT (MDCT) images, as radiologists focus on more immediate life-threatening injuries. However, early diagnosis and management are vital to reduce potential morbidity. If there is a high clinical index of suspicion for ureteral injuries with penetrating or blunt trauma, or if there is suspected iatrogenic ureteral injury, delayed-phase/urographic-phase MDCT images are essential for confirming the diagnosis. Moreover, making the distinction between partial and complete ureteral transection is critical, as it will guide management. The aim of this pictorial review is to overview the key imaging findings in blunt and penetrating traumatic and iatrogenic injuries of the ureter, as well as to discuss the advantages and disadvantages of different imaging modalities for accurately and rapidly establishing or excluding the diagnosis of ureteral injuries, with an emphasis on MDCT. The potential causes of missed ureteral injuries will also be discussed.
Utilization of the track embolization technique to improve the safety of percutaneous lung biopsy and/or fiducial marker placement
PURPOSE/OBJECTIVE:The purpose of the study was to describe and present outcomes of the track embolization technique with absorbable hemostat gelatin powder during percutaneous computed tomography (CT)-guided lung biopsy and/or fiducial marker placement versus the standard of care (no track embolization) in an attempt to decrease rates of pneumothorax (PTX), chest tube placement, hemorrhage and/or complications, and average cost per patient. MATERIALS AND METHODS/METHODS:An institutional review board-approved, case-control, retrospective study was performed in which 125 consecutive patients who underwent track embolization were compared with 124 consecutive controls at one institution. For subjects in whom the track embolization technique was utilized, it was performed passively through a coaxial needle as it was removed. All procedures were performed by one of three attending interventional radiologists. For each group, medical records and procedure images were reviewed for PTX occurring postprocedure, PTX requiring chest tube placement, and occurrence of minor or major complication and/or hemorrhage. Comparison was made with published complication rates, and a cost-per-patient analysis was performed. Statistical analysis was performed utilizing Fisher's Exact Test. RESULTS:In track embolization cases versus controls, there were statistically significant reduction in PTX (8.8% vs. 21%; P=.007) and reduction in PTX requiring chest tube placement (4% vs. 8.1%; P=.195). This compares favorably to previously published rates of PTX and chest tube placement of 8%-64% and 1.6%-17%, respectively. None of the pneumothoraces occurring at time of needle placement increased in size with use of the track embolization technique. There were no major complications (including neurological sequela) in the track embolization group. In track embolization cases versus controls, there was a statistically significant reduction in both the rate of major hemorrhage (0% vs. 4%; P=.029) and average cost per patient ($262.40 vs. $352.07; P=.044). CONCLUSIONS:CT-guided percutaneous lung biopsy and/or fiducial marker placement were safer utilizing the track embolization technique during trocar removal. In addition, this technique was cost effective in the study population.
Erratum to: CT of inferior vena cava filters: normal presentations and potential complications [Correction]
CT of inferior vena cava filters: normal presentations and potential complications
With massive pulmonary embolism (PE) being the first or second leading cause of unexpected death in adults, protection against PE is critical in appropriately selected patients. The use of inferior vena cava (IVC) filters has increased over the years, paralleling the increased detection of deep venous thrombosis (DVT) and PE by improved and more available imaging techniques. The use of IVC filters has become very common as an alternative and/or as a supplement to anticoagulation, and these filters are often seen on routine abdominal CT, including in the emergency setting; therefore, knowledge of the normal spectrum of findings of IVC filters by the radiologist on CT is critical. Additionally, CT can be used specifically to identify complications related to IVC filters, and CT may alternatively demonstrate IVC filter-related problems which are not specifically anticipated clinically. With multiple available IVC filters on the US market, and even more available outside of the USA, it is important for the emergency and the general radiologist to recognize the different models and various appearances and positioning on CT, as well as their potential complications. These complications may be related to venous access, but also include thrombosis related to the filter, filter migration and penetration, and problems associated with filter deployment. With the increasing number of inferior vena cava filters placed and their duration within patients increasing over time, it is critical for emergency and other radiologists to be aware of these findings on CT.
Pulmonary embolism diagnosed on computed tomography contrast angiography despite negative venous Doppler ultrasound after spinal surgery
STUDY DESIGN/METHODS:The focus of this study was on the frequency of negative initial/subsequent ultrasound (US) of the lower extremities but positive spinal computed tomography contrast angiography (CTA) diagnostic of pulmonary embolism (PE) among 75 patients undergoing cervical laminectomy/fusion and 165 patients having lumbar laminectomy/noninstrumented fusion. OBJECTIVE:To determine the percentage/incidence of patients undergoing spinal surgery with negative US but with positive CTA. SUMMARY OF BACKGROUND DATA/BACKGROUND:The frequency of patients with negative US but with positive CTA after spinal surgery is not well documented. METHODS:For 240 spinal surgery patients, postoperative prophylaxis against deep venous thrombosis consisted of alternating pneumatic compression stockings alone. The patients were routinely screened on postoperative days 1 to 2 for deep venous thrombosis using US. The incidence of initial/subsequent negative US and positive CTA diagnostic for PE in patients with mild/major symptoms was evaluated, in conjunction with the frequency of hypercoagulation syndromes. RESULTS:Five (6.7%) patients undergoing cervical surgery and 6 patients (3.6%) undergoing lumbar surgery exhibited negative US but positive CTA on postoperative days 1 to 21. All the patients immediately received inferior vena cava filters (2 permanent and 9 retrievable). Five patients (45%) tested positive for hypercoagulation syndromes. Two patients were fully anticoagulated on postoperative days 3 and 21 with major symptoms attributed to saddle emboli; 1 had hypercoagulation syndrome. Anticoagulation was delayed for 6 to 12 weeks in 7 patients with milder symptoms, as magnetic resonance imaging scans showed residual seromas; 4 had hypercoagulation syndromes. Two elderly patients, at high risk for falls, without hypercoagulation syndromes were not anticoagulated. CONCLUSIONS:The frequency of negative US of the lower extremities but with positive CTA for PE after 240 cervical/lumbar spinal procedures in patients with mild/major symptoms ranged from 3.6% to 6.7%; 5 of the 11 patients exhibited hypercoagulation syndromes. To avoid failure to diagnose PE after spinal surgery, one should have a "low threshold" (eg, based even on minor symptoms) for requesting the CTA.
Gadolinium-enhanced computed tomographic angiography: current status
This article reviews the research to date, as well as our clinical experience from two institutions, on gadolinium-enhanced computed tomographic angiography (gCTA) for imaging the body. gCTA may be an appropriate examination for the small percentage of patients who would benefit from noninvasive vascular imaging, but who have contraindications to both iodinated contrast and magnetic resonance imaging. gCTA is more expensive than CTA with iodinated contrast, due to the dose of gadolinium administered, and gCTA has limitations compared with CTA with iodinated contrast, in that parenchymal organs are not optimally enhanced at doses of 0.5 mmol/kg or lower. However, in our experience, gCTA has been a very useful problem-solving examination in carefully selected patients. With the advent of 16-64 detector CT, in combination with bolus tracking, we believe that the overall dose of gadolinium needed for diagnostic CTA examinations, while relatively high, can be safely administered.
Current DVT imaging
Accurate diagnosis of deep venous thrombosis (DVT) is very difficult, and imaging plays a crucial role in the diagnosis or exclusion of DVT. The initial test of choice for diagnosis of acute thigh as well as upper extremity DVT is ultrasound, because of its high accuracy, relatively low cost, portability, and lack of ionizing radiation. In patients who are undergoing CT pulmonary angiography for suspected pulmonary embolism, CT venography can be performed as part of the examination, for comprehensive evaluation of the venous system in the legs, abdomen, and pelvis. MR has a problem-solving role, and conventional venography is now limited to specific scenarios including evaluation of central DVT in the upper extremities, as a prelude to intervention for thrombolysis/thrombectomy, and prior to placement of an inferior vena cava filter. This article discusses the imaging findings of DVT, and the role of these imaging examinations in the evaluation of patients with suspected DVT.
Lower gastrointestinal bleeding from the internal iliac artery: angiographic demonstration of an iliac arteriocolic fistula [Case Report]
A rare source of potentially massive lower gastrointestinal hemorrhage in women is advanced gynecologic malignancy. Such patients can develop gastrointestinal hemorrhage with or without prior pelvic irradiation, due to arteriocolic fistulas. Angiography permits the correct diagnosis and subsequent embolotherapy.
High-dose intravenous gadolinium for renal computed tomographic angiography [Letter]