Distribution of Iliac Artery Calcification on Unenhanced Computed Tomography Scans Performed on Potential Recipients Prior to Renal Transplantation.

PURPOSE: To investigate whether a significant difference exists between the calcification of the common iliac arteries (CIAs) and the external iliac arteries (EIAs) and test for associations between clinical factors and the distribution of calcification. METHODS: A retrospective review of renal transplant candidates who underwent a routine preoperative unenhanced computed tomography yielded 214 patients. Agatston scores for the patients' left CIA, left EIA, right CIA, and right EIA were assigned. A retrospective search of patient records screened for 5 clinical factors (diabetes, hypertension, coronary artery disease [CAD], smoking, and dialysis). Data were assessed using a 2-sided t test, odds ratio, and a multivariate linear regression calculated through generalized estimating equation (GEE). RESULTS: The log-transformed Agatston scores in the CIA were found to be significantly greater than that in the EIA (t = 9.57, P < .0001), with a mean difference of 1.5078 (95% confidence interval: 1.1962-1.8194), indicating relative EIA sparing. There were no significant differences in calcification between the right and left sides. Generalized estimating equation found that CAD and smoking demonstrated independent positive associations with EIA sparing (GEE = 2.6464 [P = .0197] and 1.9092 [P = .0470], respectively). Age was also significantly associated and indicated that EIA sparing remained relatively constant throughout patients' lives (GEE = 1.0711 [P < .0001]). CONCLUSION: This study has demonstrated statistically significant EIA sparing in end-stage renal disease patients and identified CAD and smoking as associated factors. This phenomenon warrants further investigation into its biological mechanisms and the impact of EIA sparing on outcomes following transplants.

Genicular Artery Embolization for Recurrent Hemarthrosis of the Knee Following Total Knee Arthroplasty: A Single Centre Experience.

PURPOSE: To retrospectively review the safety and efficacy of genicular artery embolization procedures performed at our institution in patients presenting with recurrent knee hemarthrosis following total knee arthroplasty (TKA). MATERIALS AND METHODS: A total of 13 consecutive patients (average age: 68; range 51-84, 62% female) were identified who underwent 14 genicular artery embolization procedures after presenting with recurrent hemarthrosis after TKA. Patient charts were retrospectively reviewed for demographic information, pre-embolization investigations, and details of embolization procedure including complications, technical success, and clinical success. Each patient had failed initial conservative therapy and all patients had a diagnostic aspiration performed by the referring physician prior to the procedure. The average time between TKA and embolization in our cohort was 21 months. RESULTS: All procedures performed were technically successful, defined as elimination of periprosthetic hypervascular blush. An average of 3.6 genicular vessels were embolized in each patient; 355 to 500 µm polyvinyl alcohol (PVA) particles were used in each case. There were no cases of transient cutaneous ischemia, skin erythema, or skin necrosis. Clinical success was obtained in 85.7% of cases, defined by elimination of the presenting clinical symptoms (knee pain and swelling) during continued follow-up by the referring clinician. CONCLUSION: Particle embolization is a safe and effective treatment for recurrent hemarthrosis after arthroplasty and our experience suggests that utilizing particle sizes of greater than 300 µm appears to be important in order to avoid cutaneous ischemic complications.

Cumulative radiation dose in patients with hereditary hemorrhagic telangiectasia and pulmonary arteriovenous malformations.

PURPOSE: To determine the cumulative effective dose (CED) of radiation from medical imaging and intervention in patients with hereditary hemorrhagic telangiectasia (HHT) who have pulmonary arteriovenous malformations and to identify clinical factors associated with exposure to high levels of radiation. METHODS: All patients with at least 1 pulmonary arteriovenous malformation were identified from the dedicated patient database of a tertiary HHT referral centre. Computerized imaging and electronic patient records were systematically examined to identify all imaging studies performed from 1989-2010. The effective dose was determined for each study, and CED was calculated retrospectively. RESULTS: Among 246 patients (mean age, 53 years; 62.2% women) with a total of 2065 patient-years, 3309 procedures that involved ionizing radiation were performed. CED ranged from 0.2-307.6 mSv, with a mean of 51.7 mSv. CED exceeded 100 mSv in 26 patients (11%). Interventional procedures and computed tomography (CT) were the greatest contributors, which accounted for 51% and 46% of the total CED, respectively. Factors associated with high cumulative exposure were epistaxis (odds ratio 2.7 [95% confidence interval, 1.1-6.3]; P = .02), HHT-related gastrointestinal bleeding (odds ratio 2.0 [95% confidence interval, 1.0-3.8]; P = .04) and number of patient-years (P < .0001). CONCLUSIONS: Patients with HHT are exposed to a significant cumulative radiation dose from diagnostic and therapeutic interventions. Identifiable subsets of patients are at increased risk. A proportion of patients receive doses at levels that are associated with harm. Imaging indications and doses should be optimized to reduce radiation exposure in this population.

Pre-operative embolization of a complex systemic to pulmonary vascular malformation.

A 38-year-old male patient presenting with mild exertional dyspnea was noted to have a lingular opacity on chest radiograph. CT of the chest demonstrated an unusual complex inferior lingular vascular malformation with branches arising from the left internal thoracic artery and the left inferior diaphragmatic artery via the celiac artery. There was suspected communication with both pulmonary arterial and venous branches. Following thorough assessment and comprehensive clinical investigation, the patient elected to proceed to definitive surgical management due to potential risk of life-threatening hemoptysis. Interventional radiology performed pre-operative diagnostic angiography and embolization of the systemic feeding arteries. The patient proceeded to have an uncomplicated video-assisted thoracoscopic surgery segmentectomy and was discharged the next day. The patient was asymptomatic at follow-up with complete resolution of the malformation on CT at 6 months. We discuss an uncommon pathology which benefited from multidisciplinary management including successful pre-operative endovascular embolization.

Myocardial ischaemia secondary to ruptured abdominal aortic aneurysm.

A 63-year-old man presented to an outside hospital with presyncope, back pain, hypotension and inferior ST segment elevations. He received aspirin, ticagrelor and heparin and was transferred to our institution as a Code STEMI (ST-segment elevation myocardial infarction). A coronary angiogram demonstrated multivessel disease but no occlusive lesion for acute intervention. The following day, he developed worsening abdominal/back pain. A CT angiogram (CTA) showed a ruptured infrarenal abdominal aortic aneurysm. He underwent urgent percutaneous endovascular aneurysm repair. CTA on postoperative day (POD) 10 demonstrated a patent stent graft with no endoleak. The patient was discharged on POD 12 in stable condition.

Arteriovenous fistulas for hemodialysis: application of high-frequency US to assess vein wall morphology for cannulation readiness.

PURPOSE: To determine whether venous wall thickness and hoop (circumferential) stress, as determined with high-frequency ultrasonography (US), can predict cannulation readiness in arteriovenous fistulas (AVFs). MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for this prospective study. To determine the US appearance of the venous wall, an AVF specimen was excised and scanned in a bath of degassed lactated Ringer solution with a 55-MHz probe. The appearance of the wall at high-frequency US was correlated with histologic findings. High-frequency (40-55-MHz) US was used to image the near-field AVF venous wall of 14 men (mean age, 59 years ± 11 [standard deviation]) and six women (mean age, 55 years ± 14) with newly created AVFs within 1 week of cannulation between January 2008 and December 2009. Measurements of the intima-media thickness (IMT) were generated by three independent observers who were blinded to outcomes. Intraclass correlation analysis was performed. Cannulation readiness was defined as no extravasation during the first dialysis treatment. RESULTS: By using high-frequency US, the IMT was defined as the sum of a thin echogenic blood-intima interface and a uniform hypoechoic media. The mean IMT of the no extravasation group (0.16 mm ± 0.03) was greater than that of the extravasation group (0.10 mm ± 0.02) (P < .001). A minimum threshold IMT of 0.13 mm (P < .001) was associated with successful cannulation. The mean hoop stress of the no extravasation group (246 kPa ± 57) was lower than that of the extravasation group (530 kPa ± 199) (P < .001). A maximum hoop stress threshold of 248 kPa was associated with successful cannulation (P = .009). CONCLUSION: Venous IMT and hoop stress assessed with high-frequency US can predict cannulation readiness in AVFs that are clinically deemed mature.

Lobar embolization for treatment of diffuse pulmonary arteriovenous malformations in hereditary hemorrhagic telangiectasia: a case report.

Pulmonary arteriovenous malformations (PAVMs) are abnormal communications between pulmonary arteries and pulmonary veins that are most commonly associated with hereditary hemorrhagic telangiectasia (HHT). The authors report a case of lobar artery embolization for the treatment of diffuse PAVMs in a patient with HHT who was experiencing recurrent transient ischemic attacks despite anticoagulation and multiple previous embolizations. The right lower lobar and interlobar arteries were embolized to achieve complete occlusion of multiple PAVMs in the right lower lobe and right middle lobe. In conclusion, lobar embolization can be considered for the relief of neurologic symptoms in patients with diffuse PAVMs.

Reperfusion of Pulmonary Arteriovenous Malformations Following Embolotherapy: A Randomized Controlled Trial of Detachable Versus Pushable Coils.

PURPOSE: To compare 1 year post-embolization reperfusion rates in pulmonary arteriovenous malformations (PAVMs) treated with the 0.035″ Interlock™ Fibered IDC™ Occlusion System coils (IDC) (Boston Scientific, Marlborough, Massachusetts) versus 0.035″ Nester coils (Cook Medical Inc., Bloomington, Indiana). MATERIALS AND METHODS: A randomized controlled trial was performed randomizing individual PAVMs to treatment with IDC versus Nester coils at the largest hereditary hemorrhagic telangiectasia center in Canada. The primary outcome was CT evidence of reperfusion at 1 year. Secondary outcomes included periprocedural complications, fluoroscopy time and contrast volume. RESULTS: Our study was terminated prematurely due to slow recruitment and subsequent expiration of funding. A total of 46 PAVMs in 25 patients (64% female) were included in our study; 26 randomized to Nester coils and 20 randomized to IDC. One patient was lost to follow-up. At a mean follow-up of 421.2 ± 215.7 days, no significant difference in PAVM reperfusion was detected between Nester coils and IDC (0% vs. 5.6%, p > 0.05). No major periprocedural complications were noted in either group. Fluoroscopy time (Nester: 15.0 ± 11.8 min vs. IDC 16.0 ± 5.4 min, p > 0.05) and contrast volume (Nester: 80.3 ± 36.5 ml vs. IDC 87.3 ± 51.7 ml, p > 0.05) utilized did not differ between groups. CONCLUSION: No significant difference was detected in PAVM reperfusion rates, periprocedural complication rates, contrast volume utilization or fluoroscopy time following embolization with IDC and Nester coils.

CT Scan Does Not Differentiate Patients with Hepatopulmonary Syndrome from Other Patients with Liver Disease.

BACKGROUND: Hepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vascular dilatations, and impaired oxygenation. The gold standard for detection of intrapulmonary vascular dilatations in HPS is contrast echocardiography. However, two small studies have suggested that patients with HPS have larger segmental pulmonary arterial diameters than both normal subjects and normoxemic subjects with cirrhosis, when measured by CT. We sought to compare CT imaging-based pulmonary vasodilatation in patients with HPS, patients with liver dysfunction without HPS, and matching controls on CT imaging. METHODS: We performed a retrospective cohort study at two quaternary care Canadian HPS centers. We analyzed CT thorax scans in 23 patients with HPS, 29 patients with liver dysfunction without HPS, and 52 gender- and age-matched controls. We measured the artery-bronchus ratios (ABRs) in upper and lower lung zones, calculated the "delta ABR" by subtracting the upper from the lower ABR, compared these measurements between groups, and correlated them with clinically relevant parameters (partial pressure of arterial oxygen, alveolar-arterial oxygen gradient, macroaggregated albumin shunt fraction, and diffusion capacity). We repeated measurements in patients with post-transplant CTs. RESULTS: Patients had significantly larger lower zone ABRs and delta ABRs than controls (1.20 +/- 0.19 versus 0.98 +/- 0.10, p<0.01; and 0.12 +/- 0.17 versus -0.06 +/- 0.10, p<0.01, respectively). However, there were no significant differences between liver disease patients with and without HPS, nor any significant correlations between CT measurements and clinically relevant parameters. There were no significant changes in ABRs after liver transplantation (14 patients). CONCLUSIONS: Basilar segmental artery-bronchus ratios are larger in patients with liver disease than in normal controls, but this vasodilatation is no more severe in patients with HPS. CT does not distinguish patients with HPS from those with uncomplicated liver disease.

Low Contrast Dose Catheter-Directed CT Angiography (CCTA).

PURPOSE: Catheter-directed computed tomography angiography (CCTA) has been shown to reduce the contrast volumes required in conventional CTA, thus minimizing the risk of contrast-induced nephropathy (CIN). MATERIALS AND METHODS: A retrospective analysis was performed on cases where CCTA was used to assess access vessels prior to transfemoral aortic valve implantation (TAVI, n = 53), abdominal aortic aneurysm assessment for endovascular aneurysm repair (EVAR, n = 11), and peripheral vascular disease (PVD, n = 24). RESULTS: We show that CCTA can image vasculature with adequate diagnostic detail to allow assessment of lower extremity disease, anatomic suitability for EVAR, as well as potential contraindications to TAVI. Average contrast volumes for pre-TAVI, pre-EVAR, and PVD cases were 7, 11, and 28 mL, respectively. CONCLUSION: This study validates the use of CCTA in obtaining diagnostic images of the abdominal and pelvic vessels and in imaging lower extremity vasculature.

Development of endotension after multiple rounds of thrombolysis after endovascular aneurysm repair.

Endoleaks, defined as blood flow outside the graft but inside the aneurysm sac, are a common complication after endovascular aneurysm repair. Sometimes however, for reasons not fully understood, expansion of the aneurysm sac can occur with no identifiable endoleak, a phenomenon termed endotension, or a type V endoleak. We describe a case of endotension in a 71-year-old man that developed after recurrent stent graft thrombosis requiring thrombolysis 3 years after the initial endovascular implantation. To our knowledge, this is the first description in the literature of endotension after multiple rounds of thrombolytic treatment.

Diffusion-weighted imaging properties of uterine fibroids pre- and post-uterine fibroid embolisation.

OBJECTIVE: To determine the change in apparent diffusion coefficient (ADC) of uterine fibroids following uterine fibroid embolisation (UFE), and if the ADC change correlates with either volume loss or degree of contrast enhancement post-UFE. MATERIALS AND METHODS: This study was approved by our institutional review board with waiver of consent. The pelvic MRI examinations, including diffusion-weighted MRI (DWI) using 4 b-values, of 50 consecutive patients prior to and 6 months post-UFE were analyzed. The volume, ADC and amount of enhancement were calculated for each fibroid both pre- and post-UFE. The percent residual enhancement for each fibroid was categorized as either: no (0-1%) residual enhancement or residual (>1%) enhancement. Statistical analysis compared ADC, enhancement and volume for each fibroid pre- and post-UFE using paired t-tests and Pearson correlation coefficients. RESULTS: The mean ADC of all (n=88) fibroids pre-UFE was 1.30±0.20×10(-3)mm(2)/s, and increased to 1.68±0.24×10(-3)mm(2)/s post-UFE (p<0.0001). Lower pre-UFE ADC correlated with greater ADC change post-UFE (r=-0.50; p<0.0001). There was no correlation between ADC change and volume change post-UFE (r=0.07; p=0.59). However, fibroids with no residual enhancement post-UFE had larger ADC change than those with residual enhancement (p=0.003). CONCLUSION: The ADC of fibroids rises post-UFE. ADC change post-UFE is associated with the degree of loss of enhancement and may therefore be valuable in predicting response to treatment in pre-procedural counseling.

The potential role of optical coherence tomography in the evaluation of vulnerable carotid atheromatous plaques: a pilot study.

PURPOSE: The decision to intervene surgically in patients with carotid artery disease is based on the presence of symptoms, along with the severity of carotid artery stenosis as assessed by ultrasound or X-ray computed tomography (CT). Optical coherence tomography (OCT) is a relatively new imaging technique that offers potential in the identification of, as well as the distinction between, stable and unstable atherosclerotic plaques. The purpose of our study was to evaluate whether OCT can be used as a noninvasive diagnostic tool to reveal the morphology of carotid stenosis from the adventitial surface of the carotid artery. To achieve this aim, excised atheromatous plaques were scanned by OCT from the external surface. METHODS: Plaques removed at carotid endarterectomy were scanned by OCT from the external surface within 72 hr of surgery and then examined histologically. The images of the histologic slides and the scans were then compared. RESULTS: We examined 10 carotid endarterectomy specimens and were able to identify calcification, cholesterol crystal clefts, and lipid deposits in the OCT images with histologic correlation. The strong light scattering from the calcified tissue and cholesterol crystal clefts limited the depth of light penetration, making observation of the intimal surface and the detail of the fibrous cap difficult. However, we were able to confidently identify the absence of an atherosclerotic plaque by OCT scans even from the external surface. CONCLUSION: The results of this pilot study demonstrate that OCT can reveal the main features of carotid stenosis but that plaque vulnerability cannot be reliably and precisely assessed if scanned from the external surface with OCT in its present form.

Cutting balloon-assisted angioplasty of an anastomotic carotid-brachial bypass graft stenosis.

Neointimal hyperplasia leads to anastomotic stenosis in bypass grafts. These stenoses are often resistant to conventional balloon dilatation. We present a case of a carotid-brachial bypass graft stenosis, which was treated by a 5-mm cutting balloon angioplasty with a good angiographic and clinical result.

Renal artery embolization: a first line treatment option for end-stage hydronephrosis.

UNLABELLED: Conventionally poorly functioning hydronephrotic kidneys have been removed if they are symptomatic. In our unit, patients are offered renal artery embolization as an alternative treatment option. PATIENTS AND METHODS: Fifteen patients (11 male, 4 female) with a mean age of 32.9 yr (20-51 yrs) have undergone renal artery embolization for symptomatic hydronephrosis with poor function. Mean follow-up was 64.13 weeks (range 14-200). All patients had loin pain and hydronephrosis. Twelve patients had primary pelvi-ureteric junction obstruction (PUJO). Two patients had poorly functioning hydronephrotic kidneys secondary to chronic calculous obstruction. One patient had chronic pain in an obstructed but reasonably functioning kidney following a previous pyeloplasty for PUJO which demanded intervention. Mean split function on renography was 11% (range 0-46%). Selective renal artery embolization was carried out under antibiotic cover using a 7 Fr balloon occlusion catheter and absolute alcohol, steel coils, and polyvinyl alcohol particles. RESULTS: Nine patients developed post-embolization syndrome of self-limiting pain and pyrexia with no evidence of sepsis. One patient required readmission with this condition. One patient developed a hematoma at the puncture site. Mean hospital stay was 2.3 days. Fourteen patients are happy with the result and are completely pain free. One patient has minor discomfort but is delighted with the result. Nine patients have had follow-up ultrasound confirming resolution of the hydronephrosis. CONCLUSION: Renal artery embolization is an effective, safe, well-tolerated minimally invasive treatment option in end-stage hydronephrosis and we routinely offer it as an alternative to nephrectomy.