Computed radiography in musculoskeletal imaging

In conclusion, CR offers many advantages in comparison with conventional radiography. Musculoskeletal radiology particularly benefits from the wide dynamic range and image-processing capabilities of CR. Most studies have not shown a statistically significant difference in observer performance (diagnostic accuracy) of CR in comparison with conventional radiography in musculoskeletal applications. In addition, dose reduction in the range of 25% to 50% is possible with many musculoskeletal images. However, disadvantages are also apparent and include reduced spatial resolution, increased noise, and change in image size and format. Overall, the advantages of CR and digital technology outweigh its limitations and for these reasons continue to promote the conversion from conventional radiography.     

Storage phosphor digital mammography

Digital mammography using storage phosphor CR is still in the investigational stage. It is the only digital mammography system that has been tested in preliminary clinical trials with promising early results. Further clinical studies are needed to assess the impact of the limited spatial resolution of storage phosphor technology on its application as a digital screening mammography system. Further studies also are needed to determine the optimum image processing parameters needed in digital mammography.     

Development of hepatic pseudotumors for image-guided interventional and surgical research in a large animal model

Purpose

Real-time image guidance and navigation have become increasingly important in an era of minimally invasive interventional and surgical procedures in the liver. To develop, test, and implement tools for real-time image guidance, the authors sought to create an in vivo tumor mimic with realistic imaging and treatment capabilities.

Materials and Methods

Hepatic pseudotumors were created by injecting 1–2 mL of alginate (a hydrocolloid) directly into the liver parenchyma in eight live pigs and two dog cadavers. Tumors were imaged by B-mode ultrasound (US), US elasticity imaging, multi–detector row computed tomography (CT), CT fluoroscopy, and magnetic resonance (MR) imaging to assess imaging capabilities. Procedures performed with the alginate pseudotumors included radiofrequency (RF) ablation and robotic needle guidance.

Results

Twenty-four hepatic pseudotumors were created, ranging in size from 10 mm to 28 mm at an average depth of 6 mm. Average time of preparation and insertion was 3 minutes. All tumors were palpable under the surface of the liver and were easily visible on B-mode US, US elasticity imaging, CT, and MR imaging. Tumors were successfully “treated” with RF ablation, and gross examination of the liver showed good encompassment of the tumor by the zone of thermal coagulation. In addition, the pseudotumors allowed for easy introduction of various types of needles, including RF ablation probes and experimental steerable needles.

Conclusions

Alginate pseudotumors can easily be imaged and allow for different procedures to be performed. This model can be used for various research purposes.     

N-butyl cyanoacrylate embolization as the primary treatment of acute hemodynamically unstable lower gastrointestinal hemorrhage

Purpose

To evaluate N-butyl cyanoacrylate (NBCA) embolization as the primary treatment for patients with severe and acute hemodynamically unstable lower gastrointestinal bleeding.

Materials and Methods

Twenty-seven patients with acute, unstable hemodynamics caused by lower gastrointestinal bleeding underwent therapeutic NBCA microcatheter embolization over a period of 27 months. The inclusion criteria were hematochezia or melena and hypotension refractory to conservative treatment and requiring blood transfusion. Bleeding was localized to the rectum, colon, or small intestine in all nine such cases. Fifteen patients had severe underlying comorbidities, including sepsis, respiratory failure, malignancy, or renal failure.

Results

The procedure was technically successful in all patients. Twenty-six patients were treated solely with NBCA, and one required microcoil embolization. Embolization was performed at the level of the arteria recta or as close as possible to the point of bleeding. Immediate hemostasis occurred in all cases. Four patients experienced repeat hemorrhage, one of whom died. The other three were treated successfully with repeat NBCA embolization. None of the surviving patients had evidence of bowel ischemia. In addition, none of the patients with severe underlying disease died during the follow-up period (range, 3 mo to 2 y).

Conclusions

The present findings suggest that NBCA embolization may be a safe alternative treatment for the management of lower gastrointestinal bleeding. Further studies are warranted to confirm the findings.     

Coronary dual source multi detector computed tomography in patients suspected of coronary artery disease: Prevalence of incidental extra-cardiac findings

Objectives

(1) To establish the prevalence of incidental extra-cardiac findings (ECFs) in coronary multi detector computed tomography (CCT) performed in a large, homogeneous cohort of patients suspected of coronary artery disease (CAD). (2) To examine whether any association can be established between ECFs and pretest risk as determined by conventional risk factors for CAD, the Diamond-Forrester risk model or coronary artery calcium scores. (3) To assess cost related to extra-cardiac examinations.

Design

Retrospective study of consecutive patients who had CCT performed. A large field of view was recreated from the non-enhanced CT scan and evaluated by a radiologist for incidental ECFs.

Subjects

Patients with chest pain referred to CTA by a cardiologist.

Results

In 1383 patients a total of 481 ECFs were indentified, 378 minor (meaning no follow-up was needed) and 103 major ECFs (ECF followed up clinically and/or with additional imaging), in a total of 393 (28%) patients. 85 (6%) patients had one major ECF and 9 (0.7%) patients had two major ECFs. In 19 (4 cases of malignancy) patients the major ECF had therapeutic consequences. Significant positive associations were found between age and smoking, respectively and the presence of ECFs. The cost estimate of saving one life from malignant disease based on ECF examinations is 40,190€.

Conclusion

Incidental extra-cardiac findings are common, sometimes revealing serious, even malignant disease. Diagnostic follow-up of major ECFs seems to be cost-effective in a Danish clinical setting. We recommend investigating a large field of view for incidental ECFs following CCT.     

Hepatocellular Carcinoma: Prediction of Blood Supply from an Intercostal Artery with Multidetector Row Computed Tomography

Purpose

To evaluate the ability of multidetector row computed tomography (CT) to detect blood supply from the intercostal artery in patients with hepatocellular carcinoma (HCC).

Materials and Methods

Between January 2003 and December 2007, angiography of the intercostal artery was performed in 93 patients (76 men and 17 women, mean age 58 years) with HCC who had also undergone multidetector row CT. CT scans and digital subtraction angiograms of these patients were retrospectively reviewed by two investigators in consensus to evaluate tumor feeding vessels. Multiple logistic regression analysis was used to identify factors that predict the presence of an HCC blood supply from an intercostal artery.

Results

Tumor staining fed by an intercostal artery was noted in 65 patients (70%; 112 tumor feeding vessels) by intercostal angiography. Readers interpreted that tumor feeding vessels were evident by CT in 35 (54%) of these 65 patients with tumor staining supplied by an intercostal artery by angiography. Multiple logistic regression analysis showed that a visible tumor feeding vessel by CT (P = .003) and hepatic artery attenuation by angiography (P = .014) were significantly related to the presence of a blood supply from an intercostal artery.

Conclusions

Visualization of a tumor feeding vessel from the intercostal artery by multidetector row CT is an important sign of parasitic supply to an HCC.     

Sclerotherapy of abdominal lymphatic malformations with doxycycline

Purpose

To assess the safety and efficacy of percutaneous image-guided sclerotherapy with doxycycline as primary treatment of intraabdominal lymphatic malformations (LMs).

Materials and Methods

Retrospective review was performed of all cases of abdominal, mesenteric, or retroperitoneal LMs referred to a single center that were subsequently treated with image-guided percutaneous sclerotherapy.

Results

Ten patients were included, of whom six were male. The mean age was 13 years (range, 2–28 y). Preprocedural cross-sectional imaging demonstrated a macrocystic malformation in nine patients and a mixed macrocystic/microcystic malformation in one. The malformation was accessed under sonographic guidance, followed by injection of opacified sclerosant agent under fluoroscopic guidance. A drainage catheter was placed in eight cases, in which sclerotherapy was repeated through the catheter for another 1 day (n = 2) or 2 days (n = 6). Doxycycline was reconstituted at 10 mg/mL, with a mean per-session dose of 608 mg (range, 80–1,000 mg) and a mean total dose of 1,230 mg (range, 80–3,000 mg). Peritoneal spill was identified in one case, but the patient remained asymptomatic. No other complications were encountered. Follow-up imaging was available in eight patients: complete resolution was seen in seven, with partial resolution in one. There was no recurrence of clinical symptoms in the follow-up period.

Conclusions

Initial results indicate that percutaneous image-guided sclerotherapy of macrocystic intraabdominal LMs with doxycycline is a safe and effective procedure.     

Prophylactic embolization of renal angiomyolipomas: evaluation of therapeutic response using CT 3D volume calculation and density histograms

Purpose

To evaluate the efficacy and tolerance of prophylactic embolization of angiomyolipomas (AMLs) and to analyze the therapeutic response by using three-dimensional 3D volume calculation and 3D quantification of fatty and angiomyogenic components during computed tomography (CT) follow-up.

Materials and Methods

Over a 51-month period, 30 patients with 34 AMLs (mean diameter, 82 mm ± 37; range, 30–173 mm) underwent 37 prophylactic embolization procedures. The protocol included supraselective arterial embolization with a combination of absolute alcohol, microparticles, and coils. Mean clinical and imaging follow-up were 20.5 and 14.5 months, respectively. The 3D volume calculation and density histograms were retrospectively analyzed for treatment evaluation.

Results

Four technical failures were observed (11%), with one successful secondary reattempt, resulting in 31 AMLs (91.2%) being embolized. Thirty (88.2%) had CT follow-up and were included in the analysis. Embolization was complete after a single procedure for 25 AMLs (83%) and required two procedures in two cases. Three AMLs had incomplete embolization and were scheduled for a second procedure. Mean volume reductions were 43% ± 32 for AMLs followed for 1–6 months after embolization and 81% ± 19 for the 12 AMLs followed for more than 1 year. The volume reduction after embolization was significantly correlated with the AML initial composition, with fat-rich AMLs showing a much smaller reduction of size than predominantly angiomyomatous AMLs (P < .05).

Conclusions

Prophylactic embolization allows significant reduction of AML volume with a high success rate. Three-dimensional CT volume and density histogram calculations suggest that it is especially effective on angiomyogenic components and fat-poor AMLs.     

CT fluoroscopy-guided placement of inferior vena cava filters: feasibility study in pigs

Purpose

To evaluate the feasibility of computed tomography (CT)–guided placement of inferior vena cava (IVC) filters in a swine model.

Materials and Methods

Five domestic pigs (60–70 kg) underwent transfemoral and transjugular IVC filter placement under real-time CT fluoroscopic guidance. Filter position was confirmed by contrast-enhanced CT and digital subtraction angiography. Filter tilt, distance to target position, and fluoroscopy time were analyzed.

Results

A total of 10 filters were successfully implanted (five via transfemoral approach, five via transjugular approach) without complications. The mean distance to the target position was 0.3 cm ± 0.2. Mean filter tilt was 3.2° ± 2.3 (range, 0°–7°), without differences between deployment techniques (P = .8486). Average fluoroscopy time was 25.9 s ± 6.9 per procedure.

Conclusions

CT fluoroscopy–guided placement of IVC filters is safely feasible. Use of this technique may avoid the need to move critically ill patients.     

Digital radiography of the chest

Digital radiography is an appropriate method for both bedside and in-department chest radiographs. Its major advantage in bedside chest radiography is its control of the displayed optical density of these radiographs. With dynamic range control processing, it improves the visibility of tubes and lines superimposed on the mediastinal tissues. When used for in-department chest radiography, it may offer slight advantages in the evaluation of disease in the mediastinum, but in general is equivalent to film-screen chest radiography. The main reasons for using digital chest radiography for in-department chest radiographs relate mainly to its use as a data entry point method of projection radiography for high-quality teleradiology or for its use in a picture archiving and communication system. Apart from these advantages, there is no reason to change from conventional to digital chest radiographs. Digital radiographs are, with certain systems, printed at smaller than life size. Because of this, there is a necessary period of learning as radiologists adjust to the new image size. The most important change in radiologists' work pattern appears to be the need to sit closer to the film. Findings of disease are smaller, but, with experience, just as easy to see.     

A method for following patients with retrievable inferior vena cava filters: results and lessons learned from the first 1,100 patients

Purpose

Patients who have undergone implantation of a retrievable inferior vena cava (IVC) filter require continued follow-up to have the device removed when clinically appropriate and in a timely fashion to avoid potential long-term filter-related complications. The efficacy of a method for patient follow-up was evaluated based on a retrospective review of a single-institutional retrievable IVC filter experience.

Materials and Methods

Patients with retrievable IVC filters were tracked via a prospectively collected database designed specifically for patient follow-up. Follow-up consisted of periodic review of the electronic medical record. Patients were contacted by mail (at regular intervals one or more times) when removal of the filter was deemed appropriate. A retrospective review of the ultimate fate of the first 1,127 retrievable IVC filters placed at a single institution was performed. Retrieval rates were compared with those seen in the initial experience, during which no structured follow-up was performed.

Results

Of 1,127 filters placed, 658 (58.4%) were removed. Filter removal or declaration of the device as permanent was achieved in 860 patients (76.3%). Filter removal, declaration of the device as permanent, or establishment of the need for continued follow-up was achieved in 941 patients (83.5%). Only 186 patients (16.5%) were lost to follow-up.

Conclusions

The follow-up method described in the present study resulted in a statistically significant difference (P < .001) in the likelihood of a patient returning for IVC filter removal compared with a lack of follow-up (59% vs 24%).     

Experimental model of large pulmonary embolism employing controlled release of subacute caval thrombus in swine

Purpose

To develop a catheter-based model of large pulmonary embolism (PE) in swine based on in situ venous thrombus formation.

Materials and Methods

Ten Yorkshire swine underwent transjugular implantation of a retrievable inferior vena cava (IVC) filter. A thrombin and collagen mixture was injected into a confined space created by two balloons inflated proximal and distal to the IVC filter. Animals were left to survive for 7 days ± 3 to allow thrombus to organize in situ. The caval thrombus was released on transcatheter retrieval of the IVC filter and embolized into the main and branch pulmonary arteries. The severity of PE was scored based on digital subtraction angiography with the Miller index. At necropsy, thrombi were recovered and analyzed histopathologically.

Results

Large PE was induced in all animals (Miller index score of 15 ± 5). Two animals developed saddle embolus with bilateral pulmonary artery occlusion, and five developed proximal occlusion of the left or right pulmonary artery. Nevertheless, no animal exhibited significant hemodynamic compromise. Large tubular thrombi were explanted in the size range of 5–10 cm long and 0.5–1 cm wide. Histologic analysis indicated an organized thrombus with infiltration of white blood cells and fibrin deposition.

Conclusions

Large caval thrombi can be formed in vivo and released at a predetermined time to induce large PE in a large animal model. This may help in the development and testing of new therapeutic approaches for PE.     

Incidence and management of inferior vena cava filter thrombus detected at time of filter retrieval

Purpose

To evaluate inferior vena cava (IVC) venograms (ie, cavograms) before filter retrieval to determine the incidence and volume of filter thrombus relative to filter dwell time and evaluate subsequent changes in thrombus volume with additional anticoagulation.

Materials and Methods

IVC filter retrieval attempts between December 2002 and June 2010 were retrospectively reviewed to determine the incidence of filter thrombus and estimate thrombus volume on a preretrieval cavogram. Correlation between filter dwell times (assessed at 30-d intervals) and incidence and volume of thrombus was assessed. Follow-up images and management of filters with thrombus that were not initially removed were analyzed.

Results

A total of 463 retrieval attempts were performed in 440 patients, with a mean filter dwell time of 95 days ± 145 (SD; range, 0–1,762 d). Thirty (6.5%) had filter thrombus on initial cavograms, with a mean thrombus volume of 2.8 cm³ ± 7.3 (range, 0.04–40.02 cm³). Incidence rate and estimated thrombus volume were highest in the 0–30-day dwell interval (8.0% and 6.3 cm³, respectively) and decreased at subsequent time intervals. On linear regression analysis, incidence of filter thrombus was inversely related to dwell time (P < .05; correlation coefficient, −0.86). Seven patients with thrombus underwent additional anticoagulation for a mean of 48 days ± 25 (range, 14–90 d); thrombus resolved completely in five (71%) and partially in one (14%), and increased in one (14%).

Conclusions

The incidence of filter thrombus at the time of filter retrieval appears to decrease with dwell time. If thrombus is detected, an additional period of anticoagulation is likely to reduce the thrombus burden and facilitate later retrieval.