Angiogenesis and current antiangiogenic strategies for the treatment of cancer

Angiogenesis is a complex process critical for embryonic development and for survival. It is also a critical player in many pathologic processes, most notably in neoplasia. The cell signaling pathways involved in angiogenesis have become key targets for drug design, with more than 2,500 clinical trials currently under way. This review summarizes the essential features of angiogenesis and discusses therapeutic strategies that have been applied to specific diseases known to be associated with perturbation of normal angiogenic control.

Percutaneous transcatheter arterial embolization of inferior pancreatico-duodenal artery aneurysms associated with celiac artery stenosis or occlusion

OBJECTIVES

To report our experience with percutaneous TAE of true IPDA aneurysms.

BACKGROUND

Most IPDA aneurysms are ruptured at presentation causing a high mortality risk. Minimally invasive treatment approaches may improve overall outcomes in such patients.

METHODS

Between 1996 and 2007, seven patients (5 Males; mean age 55 y) with symptomatic IPDA aneurysms and severe degree (>75%) celiac artery stenosis were treated with percutaneous TAE. The medical and imaging records were reviewed for demographics, clinical presentation, treatment, complications and follow-up. Patients presented with epigastric pain (7/7), hemodynamic shock (2/7) and rectal bleeding (2/7). Selective catheter angiography was performed in all patients with the intent to embolize the aneurysms.

RESULTS

A total of nine aneurysms were seen in seven patients. Two patients had two aneurysms each. The aneurysms ranged in size from 0.5 to 4.0 cm (mean 1.9 cm). Trans-catheter coil embolization was successful in 8/9 (89%) aneurysms in 6 patients. Following unsuccessful TAE of one aneurysm in one of the patient, the aneurysm was treated successfully with direct CT-guided percutaneous transabdominal injection of N-butyl-2-cyanoacrylate. There were no complications on follow up. Angioplasty and stenting of the celiac artery were performed in one patient for complete occlusion. None of the patients developed clinical or imaging evidence of visceral ischemia following embolization. None had recurrent symptoms during clinical follow-up (median 3 years, range 0.5-13.5 years). Follow-up CT (Median 6.6 months, range 4 days-11.5 years) in all patients showed no recurrence of the aneurysm.

CONCLUSION

IPDA aneurysms associated with celiac axis stenosis can be successfully treated with percutaneous embolization with minimal recurrence.

Recent advances in transarterial therapy of primary and secondary liver malignancies

The management of liver malignancies presents many challenges. Few patients with primary hepatocellular carcinoma or metastatic disease of the liver are eligible for surgery, which is the only curative therapeutic option. Because the hepatic tumor burden is often a determinant of eligibility for surgery and is a primary contributor to morbidity and mortality, an increasing number of innovative techniques based on the transarterial administration of liver-directed drug-eluting or radiation-emitting microspheres are being tested for use in cytoreductive and palliative therapy. The delivery of therapy via a transarterial route takes advantage of the fact that hepatic malignancies are primarily supplied by the hepatic artery. The early results of clinical trials are promising; the clinical effectiveness and safety of drug-eluting and yttrium-90-bearing microspheres have been demonstrated; however, further clinical investigation is needed to verify a benefit in survival. Transarterially administered gene therapy holds promise but is still in the early stages of investigation. For all transarterial therapies, the outcome depends heavily on meticulous patient selection, careful preparation and administration of therapy, and early and regular follow-up evaluations by using an interdisciplinary approach.

Is Upper Extremity Deep Venous Thrombosis Underdiagnosed in Trauma Patients?

It has been suggested that upper extremity deep venous thrombosis (UEDVT) is as common and dangerous as lower extremity deep venous thrombosis. Pulmonary embolism (PE) is often found with no evidence of associated lower extremity deep venous thrombosis and could have originated from UEDVT. Routine screening is well accepted for lower extremity deep venous thrombosis but not for UEDVT. We hypothesized that UEDVT in trauma is frequent but undetected; therefore, routine screening of trauma patients at risk will increase the UEDVT rate and decrease the PE rate due to early diagnosis and treatment. We evaluated the incidence of UEDVT and PE over 6 months before (Group BEFORE) and 6 months after (Group AFTER) implementing a policy of screening patients at high risk for deep venous thrombosis with Duplex ultrasonography. Group BEFORE was evaluated retrospectively and group AFTER prospectively. There were 1110 BEFORE and 911 AFTER patients. The two groups were similar. Of the AFTER patients, 86 met predetermined screening criteria and were evaluated routinely by a total of 130 Duplex exams. One patient in each group developed UEDVT (0.09% vs 0.11%, P = 1.00). The brachial vein was involved in both patients. Six BEFORE (0.54%) and 1 AFTER (0.11%) patients developed PE ( P = 0.137). The single AFTER patient with PE was not screened for UEDVT because he had no high-risk criteria. UEDVT is an uncommon event with unclear significance in trauma. Aggressive screening did not result in a higher rate of UEDVT diagnosis, nor an opportunity to prevent PE.

Is upper extremity deep venous thrombosis underdiagnosed in trauma patients?

It has been suggested that upper extremity deep venous thrombosis (UEDVT) is as common and dangerous as lower extremity deep venous thrombosis. Pulmonary embolism (PE) is often found with no evidence of associated lower extremity deep venous thrombosis and could have originated from UEDVT. Routine screening is well accepted for lower extremity deep venous thrombosis but not for UEDVT. We hypothesized that UEDVT in trauma is frequent but undetected; therefore, routine screening of trauma patients at risk will increase the UEDVT rate and decrease the PE rate due to early diagnosis and treatment. We evaluated the incidence of UEDVT and PE over 6 months before (Group BEFORE) and 6 months after (Group AFTER) implementing a policy of screening patients at high risk for deep venous thrombosis with Duplex ultrasonography. Group BEFORE was evaluated retrospectively and group AFTER prospectively. There were 1110 BEFORE and 911 AFTER patients. The two groups were similar. Of the AFTER patients, 86 met predetermined screening criteria and were evaluated routinely by a total of 130 Duplex exams. One patient in each group developed UEDVT (0.09% vs. 0.11%, P = 1.00). The brachial vein was involved in both patients. Six BEFORE (0.54%) and 1 AFTER (0.11%) patients developed PE (P = 0.137). The single AFTER patient with PE was not screened for UEDVT because he had no high-risk criteria. UEDVT is an uncommon event with unclear significance in trauma. Aggressive screening did not result in a higher rate of UEDVT diagnosis, nor an opportunity to prevent PE.

Inferior pancreaticoduodenal artery aneurysms in association with celiac axis stenosis or occlusion

PURPOSE

To describe the pathophysiology, identification and management of inferior pancreaticoduodenal artery aneurysms in association with celiac axis stenosis or occlusion has been reported.

REVIEW FINDINGS

These aneurysms are thought to arise due to increased flow through the pancreaticoduodenal arcades. The arcades first enlarge, and then form focal aneurysms which may rupture. The aneurysms can be treated through endovascular techniques or by surgery, though the former is a preferred approach.

TrapEase Vena Cava Filter:Experience in 751 Patients

PURPOSE

To evaluate the clinical safety and efficacy of the TrapEase vena cava filter in a 4-year single-center experience.

METHODS

The clinical and imaging data of 751 patients (384 men; mean age 64 years, range 16-99) who had a TrapEase inferior vena cava (IVC) filter placed between January 1, 2001, and December 31, 2004, were reviewed retrospectively. More than a third of patients (297, 39.5%) presented with pulmonary embolism (PE), 188 (25.0%) had deep vein thrombosis (DVT), 40 (5.3%) had both PE and DVT, and the rest (226, 30.1%) had other symptoms. Indications for filter placement were contraindication to anticoagulation (461, 61.4%), complication of anticoagulation (42, 5.6%), failure of anticoagulation (39, 5.2%), and prophylaxis (209, 27.8%). Filters were placed in the infrarenal (n=738) or suprarenal (n=13) position through a femoral (n=729) or jugular vein (n=22) approach. Follow-up computed tomographic (CT) scans of the chest and abdomen were evaluated for recurrent PE and filter-related complications, respectively.

RESULTS

Three (0.4%) patients developed groin hematoma. During a mean 295-day clinical follow-up (range 1-1677), 55 (7.5%) patients developed symptoms of PE, and 1 (0.1%) death was attributed to PE. Chest CT performed for various clinical indications in 219 patients at a mean 192 days (range 1-1346) showed PE in 15 (6.8%) patients; 10 were symptomatic and 5 asymptomatic, but there were no fatalities. Follow-up abdominal CT (n=270) at a mean 189 days (range 1-1415) showed fracture of filter components in 8 (3.0%), thrombus within the filter in 68 (25.2%), thrombus extending beyond the filter in 4 (1.5%), near total caval occlusion in 2 (0.7%), and no cases of migration.

CONCLUSION

The TrapEase vena cava filter is effective in the prevention of pulmonary embolism, with minimal complications.

“Recovery™” Vena Cava Filter: Experience in 96 Patients

The purpose of the study was to assess the clinical safety and efficacy of the "Recovery(TM)" (Bard) inferior vena cava (IVC) filter. We retrospectively evaluated the clinical and imaging data of patients who had a "Recovery(TM)" IVC filter placed between January 2003 and December 2004 in our institution. The clinical presentation, indications, and procedure-related complications during placement and retrieval were evaluated. Follow-up computed tomography (CT) examinations of the abdomen and chest were evaluated for filter-related complications and pulmonary embolism (PE), respectively. "Recovery" filters were placed in 96 patients (72 males and 24 females; age range: 16-87 years; mean: 46 years). Twenty-four patients presented with PE, 13 with deep vein thrombosis (DVT) and 2 with both PE and DVT. The remaining 57 patients had no symptoms of thromboembolism. Indications for filter placement included contraindication to anticoagulation (n = 27), complication of anticoagulation (n = 3), failure of anticoagulation (n = 5), and prophylaxis (n = 61). The device was successfully deployed in the infrarenal (n = 95) or suprarenal (n = 1) IVC through a femoral vein approach. Retrieval was attempted in 11 patients after a mean period of 117 days (range: 24-426). The filter was successfully removed in nine patients (82%). Failure of retrieval was due to technical difficulty (n = 1) and the presence of thrombus in the filter (n = 1). One of the nine patients who had the filter removed developed IVC thrombus after retrieval and another had an intimal tear of the IVC. Follow-up abdominal CT (n = 40) at a mean of 80 days (range: 1-513) showed penetration of the IVC by the filter arms in 11, of which 3 had fracture of filter components. In one patient, a broken arm migrated into the pancreas. Asymmetric deployment of the filter legs was seen in 12 patients and thrombus within the filter in 2 patients. No filter migration or caval occlusion was encountered. Follow-up chest CT (n = 27) at a mean of 63 days (range: 1-386) showed PE in one patient (3%). During clinical follow-up, 12 of 96 patients developed symptoms of PE and only 1 of the 12 had PE on CT. There was no fatal pulmonary embolism in our group of patients following "Recovery" filter placement. However, the current version of the filter is associated with structure weakness, a high incidence of IVC wall penetration, and asymmetric deployment of the filter legs.

Mediastinal bronchial artery aneurysms: Endovascular therapy in two patients

We report two patients with cystic fibrosis and mediastinal bronchial artery aneurysms treated by means of endovascular coil embolization. In one case, the presence of a long segment of bronchial artery proximal to the aneurysm allowed coil embolization with regular steel coils. In the second case, the aneurysm was near the origin of the bronchial artery from the aorta. We used detachable coils to occlude this aneurysm for more precise embolization.

A novel model to test accuracy and reproducibility of MDCT scan protocols for coronary calcium in vivo

OBJECTIVES

We compared the accuracy and reliability of prospectively triggered, retrospectively ECG gated, and non-gated CT image reconstruction for measurements of coronary artery calcification (CAC) in vivo using a novel animal model.

MATERIALS AND METHODS

In six Yorkshire farm pigs, prefabricated chains of cortical bone fragments were sutured over the epicardial bed of the major coronary arteries. Using a 4-slice MDCT scanner, each animal was imaged with two different protocols: sequential acquisition with prospective ECG triggering, and spiral acquisition with retrospectively ECG gated image reconstruction- non-gated reconstructions were also generated from these latter scans. Two independent observers measured the 'Agatston score' (AS), the calcified volume (CV), and mineral mass (MM). To calculate accuracy of MM measurements the ash weight of the burned bone fragments was compared to MDCT derived MM.

RESULTS

Six pigs successfully underwent surgery and CT imaging (mean heart rate: 86+/-12 bpm). MM measurements from prospectively ECG triggered CT sequential scans were more accurate (p<0.02) and reproducible (p=0.05) than sequential CT scans without ECG triggering or spiral acquisition using retrospective ECG gating.

CONCLUSIONS

At high heart rates prospective ECG triggered image reconstruction is more accurate and reproducible for CAC scoring than retrospective ECG gated reconstruction and non-gated reconstruction.

Aortoiliac Gadolinium-enhanced CT Angiography: Improved Results with a 16–Detector Row Scanner Compared with a Four–Detector Row Scanner

PURPOSE

To assess the level of vascular enhancement of gadolinium-enhanced aortoiliac computed tomographic (CT) angiography with a 16-detector row CT scanner and to compare it with the results of previous similar studies that used four-detector row CT units.

MATERIALS AND METHODS

Eleven gadolinium-enhanced CT angiograms were obtained in 10 consecutive patients with contraindication to iodinated contrast medium with use of a 16-detector row CT scanner. In the region of interest, attenuation measurements (in HU) were obtained from the proximal abdominal aorta to the common femoral arteries during unenhanced, gadolinium-enhanced, and delayed acquisitions. The results were compared to those in the 15 consecutive patients who most recently had similar examinations performed on a four-detector row CT unit. Phantom studies with diluted gadolinium were conducted to compare attenuation between CT units.

RESULTS

On four-detector row CT, throughout the scan length, mean enhancement values were 53.8 HU +/- 5.3 and 15.0 HU +/- 2.6 for gadolinium-enhanced and delayed series, respectively. For the 16-detector row CT unit, they were 76.1 HU +/- 3.4 and 21.3 HU +/- 1.3, respectively. As a result of a shorter scan time and a more optimal start time, the 16-detector row CT unit provided significantly greater and more consistent enhancement throughout the scan length compared with the four-detector row CT unit (P =.0106). Similar structures had significantly greater enhancement when 120 kV was applied instead of 140 kV (P =.0495)

CONCLUSION

The 16-detector row CT scanner improved gadolinium-enhanced CT angiography results compared with the four-detector row CT unit.

Clinical experience with retrievable Günther Tulip vena cava filters

PURPOSE

To report clinical experience with retrievable Günther Tulip filters from implantation to retrieval and their status in nonretrieved situations.

METHODS

Seventy-five Günther Tulip filter implantations were performed in 71 patients (43 women; mean age 55 years). Indications for filter placement were pulmonary embolism (PE) or iliofemoral deep vein thrombosis (DVT) in patients with a contraindication to anticoagulation (43, 61%) or perioperative PE prophylaxis (28, 39%) in patients with confirmed iliofemoral DVT. Retrieval procedures were planned for each patient. Patients with nonretrieved filters were followed with plain radiography and duplex sonography.

RESULTS

Technical success of filter insertion was 97.3% (73/75). Eighteen (25%) patients died from unrelated causes prior to retrieval attempts, and 6 other patients were too critically ill for a retrieval procedure. Of 49 (67%) planned retrieval attempts, 14 (19%) filters could not be removed owing to large trapped thrombi. The mean implantation period for the 35 (48%) retrieved filters was 8.2 days (range 1-13). Delivery tilt was observed in 12 (16%) filters and during retrieval attempts in 1 more case. For 9 nonretrieved filters, tilt and migration were observed in 22% at a mean follow-up of 30 months, but no venous thrombosis was assessed.

CONCLUSIONS

Our data confirm the clinical efficacy of the Günther Tulip filter during implantation and the feasibility of its retrieval. Further long-term follow-up should be conducted on nonretrieved filters to confirm our results.

assessment of coronary remodeling in stenotic and nonstenotic coronary atherosclerotic lesions by multidetector spiral computed tomography

OBJECTIVES

This study was designed to investigate whether contrast-enhanced multidetector spiral CT (MDCT) permits assessment of remodeling in coronary atherosclerotic lesions.

BACKGROUND

With sufficient image quality, MDCT permits noninvasive visualization of the coronary arteries, but its ability to assess remodeling has not been evaluated.

METHODS

Out of 102 patients in whom MDCT (16-slice scanner, intravenous contrast, 0.75-mm collimation, 420 ms rotation) was performed before invasive coronary angiography, 44 patients with high-quality MDCT data sets showing atherosclerotic plaque in a proximal coronary artery segment were chosen for evaluation. In multiplanar reconstructions orthogonal to the coronary artery, the cross-sectional vessel area was measured for the respective lesion and for a reference segment proximal to the lesion. The "Remodeling Index" was calculated by dividing the vessel area in the lesion by the reference segment. Results were correlated to the presence of stenosis (>50% diameter reduction) in invasive angiography. In a subset of 13 patients, MDCT measurements were verified by IVUS.

RESULTS

Reference vessel area was not significantly different between nonstenotic versus stenotic lesions (20 +/- 8 mm(2), n = 23 vs. 22 +/- 8 mm(2), n = 21). The mean Remodeling Index was significantly higher in nonstenotic than in stenotic lesions (1.3 +/- 0.2 vs. 1.0 +/- 0.2, p < 0.001). In five stenotic lesions, "negative remodeling" (Remodeling Index < or = 0.95) was observed. Cross-sectional vessel areas and Remodeling Indices measured by MDCT correlated closely to IVUS (r(2) = 0.77 and r(2) = 0.82, respectively).

CONCLUSIONS

Multidetector spiral CT may permit assessment of remodeling of coronary atherosclerotic lesions in selected data sets of sufficient quality.

Tomographic coronary angiography by EBCT and MDCT

Fast, cross-sectional computed tomography (CT) imaging permits visualization of the coronary artery lumen after intravenous injection of contrast agent. Electron beam CT and multidetector row spiral CT have both been shown to allow detection of coronary artery stenoses with high sensitivity and specificity in selected patient subsets. However, limitations of image quality may render some coronary artery segments unevaluable, in most cases because of severe calcification or remaining motion artifacts. In the future, these imaging modalities may play a clinically important role in ruling out coronary artery stenoses, especially in patients with relatively low likelihood of disease. Other applications include the analysis of bypass patency and evaluation of coronary anomalies.