Hiroki Higashihara

Long-term Outcomes of Coil Packing for Visceral Aneurysms: Correlation between Packing Density and Incidence of Coil Compaction or Recanalization

PURPOSE To evaluate the correlation between packing density and the incidence of coil compaction or recanalization of visceral artery aneurysms (VAAs) after coil packing. MATERIALS AND METHODS Between July 2004 and April 2012, coil packing was performed for 46 true visceral aneurysms (16 splenic, 11 pancreaticoduodenal, eight renal, six hepatic, three superior mesenteric, one right gastric, and one gastroepiploic) in 42 patients. The size and volume of the aneurysm, packing density, and the incidences of compaction and recanalization were evaluated retrospectively. RESULTS The mean follow-up period was 37 months ± 8 (range, 11-80 mo). The mean packing density was 19% ± 8 (range, 5%-42%), mean aneurysm size was 19 mm ± 8 (range, 5-40 mm), and mean volume was 4,108 mm(3) ± 5,435 (range, 72-26,235 mm(3)). Compaction and recanalization occurred in two (4%) and 12 aneurysms (26%), respectively. The mean packing density was significantly lower in aneurysms with compaction or recanalization than in unaffected aneurysms (12% vs 22%; P = .00014). There was a significant difference in mean packing density between small (< 20 mm; 22%) and large (≥ 20 mm) aneurysms (15%; P = .0045). The mean size and volume were significantly larger for coil-compacted or recanalized aneurysms than for unaffected aneurysms (P < .05). In aneurysms with a packing density of at least 24%, no compaction or recanalization occurred. CONCLUSIONS Coil compaction or recanalization after coil packing for VAAs more often occurs after insufficient embolization with low packing density and in patients with large aneurysms.

Current status of embolic agents for liver tumor embolization

Gelatin sponge and polyvinyl alcohol particles have been the most popular particulate embolic agents for transarterial chemoembolization (TACE) of liver tumors. Over the last decade, calibrated microspheres have been introduced and increasingly used in liver tumor embolization in Western countries. In addition, drug-eluting beads (DEB) have been introduced for sustained local drug release. Such long-awaited spherical embolic agents will be introduced in Japan in the near future. The advantages of these microspheres are that particles are uniform in size and shape, and easy to inject through a microcatheter. They can travel distally to vessels corresponding to the particle size; in other words, the occlusion level can be predicted according to the particle size chosen. Thus, new bland microspheres and DEB may bring a significant advancement to embolization for primary liver tumors as well as hepatic metastases from various cancers. However, at this point, the published data suggests that both conventional TACE and DEB-TACE are equally effective for treatment of unresectable hepatocellular carcinoma, when patients are carefully selected. Therefore, indication, patient selection, and embolization techniques will be essential in order to individually adapt newer embolic agents based on oncological, anatomical and technical considerations.

Angiographic evaluation of hepatic arterial damage after transarterial chemoembolization for hepatocellular carcinoma

PurposeThe aim of this study was to assess the incidence, degree, and predictors of hepatic arterial damage (HAD) after transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC).Materials and methodsA total of 33 patients with unresectable HCC underwent TACE alone using a mixture of iodized oil, epirubicin, and gelatin sponge. A follow-up angiogram was available for 76 of 109 sessions, and HAD was evaluated at each subsegment of the hepatic artery using a three-grade scale (1, no or slight wall irregularity; 2, overt stenosis; 3, occlusion). Grades 2 and 3 were considered to indicate significant HAD. The predictors of HAD were analyzed by multivariate analysis.ResultsA total of 161 hepatic arteries were embolized from the lobar (n = 43), segmental (n = 40), subsegmental (n = 72), or more distal (n = 6) level. The follow-up period between the initial and last sessions ranged from 70 to 1505 days (median 497 days). Significant HAD occurred in 37 of 231 subsegmental hepatic arteries (16%) and in 16 of 33 patients (48%). The accumulated dose of epirubicin per artery (P = 0.001) and Child-Pugh score (P < 0.001) were significant predictors.ConclusionTACE is more likely to induce HAD in cirrhotic patients with impaired liver function and when a high dose of the chemotherapeutic agent was used.

Determining the optimal timing for early arterial phase hepatic CT imaging by measuring abdominal aortic enhancement in variable contrast injection protocols

Objective: To find the optimal scan timing for early arterial phase hepatic CT with adequate arterial enhancement after the aortic contrast arrival. Methods: Sixty patients were divided randomly into three groups, each of which received 2.0 mL/kg of the 300 mgI/mL contrast medium with an injection duration of 30 seconds (Group A, mean rate 3.6 mL/sec); of 25 seconds (B, 4.6 mL/sec); of 30 seconds (3.6 mL/sec) followed by a saline chaser (C). Results: After the contrast arrival, aortic enhancement increased rapidly for 6-15 seconds (mean, 10 seconds) to the initial peak enhancement in all groups, and then, increased moderately to the maximum aortic enhancement over the following 19, 13, and 21 seconds, respectively. The mean maximum aortic enhancement in Group B (392 HU) and C (360 HU) were significantly higher than that in A (326 HU), respectively. The difference between the initial and maximum aortic enhancement was less than 50 HU. Conclusion: The optimal timing of the early arterial phase for hepatic CT arteriography is 10-15 seconds after the aortic arrival.

In vitro characterization of cisplatin-loaded superabsorbent polymer microspheres designed for chemoembolization.

PURPOSE To find appropriate contrast media to load cisplatin into superabsorbent polymer (SAP) and to analyze the absorption and elution kinetics of cisplatin to and from SAP. MATERIALS AND METHODS Three contrast media-ioxaglic acid 320 mg/mL, iohexol 300 mg/mL, and iopamidol 300 mg/mL-were tested for solubility of a new highly soluble cisplatin powder. The appropriate concentrations of cisplatin were predetermined according to the solubility in each contrast medium. For each concentration, we assessed the cisplatin elution kinetics with an atomic absorption spectrophotometer. The SAP particle diameters (106-150 microm dry size) before and after drug elution were also measured. RESULTS The concentrations of cisplatin were predetermined as 2.5 mg/mL in ioxaglic acid, 2.5 mg/mL in iohexol, and 5.0 mg/mL in iohexol. At these concentrations, 100 mg of SAP carried 5 mg, 25 mg, and 50 mg of cisplatin dissolved in ioxaglic acid (2.5 mg/mL) and iohexol (2.5 mg/mL and 5.0 mg/mL), respectively. Cisplatin-loaded SAP in ioxaglic acid and iohexol exhibited similar elution profiles, with cisplatin fractions of 15%, 40%, 70%, and 95% at 1, 3, 6, and 24 hours, respectively. By drug elution, the mean particle diameter changed from 0.31 mm to 0.61 mm in ioxaglic acid (2.5 mg/mL), from 0.54 mm to 0.60 mm in iohexol 2.5 mg/mL, and from 0.63 mm to 0.59 mm in iohexol 5.0 mg/mL. CONCLUSIONS SAP was confirmed to absorb and elute cisplatin within 24 hours. When mixed with iohexol, SAP carried a ten times larger dose of cisplatin and expanded twice as large as when mixed with ioxaglic acid. Cisplatin-loaded SAP may have potential as a drug delivery system for the clinical treatment of liver tumors.

Usefulness of contrast-enhanced three-dimensional MR angiography using time-resolved imaging of contrast kinetics applied to description of Extracranial Arteriovenous Malformations: Initial Experience

PURPOSE The purpose of this study was to evaluate the usefulness of contrast-enhanced three-dimensional MR angiography using time-resolved imaging of contrast kinetics (TRICKS-MRA) to demonstrate extracranial arteriovenous malformations (E-AVMs). MATERIALS AND METHODS TRICKS-MRA was performed in 33 patients (adults; n = 30, children; n = 3) with E-AVMs. Four different scan protocols were arranged based on the size of E-AVM, and serial images were acquired from the start of contrast injection with a time frame ranging from 1.2 to 7.1s. Demonstration of feeding arteries and drainage veins, and the extent of nidus was qualitatively graded using a three-point scale. In sixteen patients who underwent DSA 3 days to 15 months after TRICKS-MRA, the comparability of TRICKS-MRA to DSA was evaluated using a three-point scale. In each category, score of 3 or excellent was defined as the positive result. RESULTS Demonstration of the feeding arteries, the drainage veins, and the extent of nidus were graded as excellent in 68%, 65%, and 58% of the patients, respectively. Comparability of TRICKS-MRA to DSA was excellent in 75%, 88%, and 88% of the sixteen patients who underwent DSA. CONCLUSION TRICKS-MRA is a feasible and useful vascular imaging technique to provide time-resolved analysis of angioarchitecture of E-AVMs.

64-slice multidetector row computed tomographic angiography of aortoiliac and lower extremity arteries: efficacy of test injection using a monitoring scan at knee level.

To evaluate the efficacy of test injection technique using a monitoring scan at knee level for 64-slice multidetector row computed tomographic (MDCT) angiography of the abdominal and lower extremity arteries. Methods: The test injection technique using low-dose serial CT scan at knee level was performed for 58 patients. Time elapsed from contrast material injection to peak enhancement for the popliteal arteries was applied to scan delay for CT angiography. 64-Slice MDCT angiography of the abdominal and lower extremity arteries obtained with a table speed of 137.5 mm/s was evaluated. Results: The time to peak enhancement was unavailable in 2 cases. CT angiographic images were of good quality in 54 cases, whereas prominent enhancement of abdominal veins was observed in 2 cases. Conclusions: The test injection using a monitoring scan at knee level was found to be useful for 64-slice MDCT angiography of the abdominal and lower extremity arteries.

Abdominal multi-detector row CT: Effectiveness of determining contrast medium dose on basis of body surface area

PURPOSE To investigate the validity of determining the contrast medium dose based on body surface area (BSA) for the abdominal contrast-enhanced multi-detector row CT comparing with determining based on body weight (BW). MATERIALS AND METHODS Institutional review committee approval was obtained. In this retrospective study, 191 patients those underwent abdominal contrast-enhanced multi-detector row CT were enrolled. All patients received 96 mL of 320 mg I/mL contrast medium at the rate of 3.2 mL. The iodine dose required to enhance 1 HU of the aorta at the arterial phase and that of liver parenchyma at portal venous phase per BSA were calculated (EUBSA) and evaluated the relationship with BSA. Those per BW were also calculated (EUBW) and evaluated. Estimated enhancement values (EEVs) of the aorta and liver parenchyma with two protocols for dose decision based on BSA and BW were calculated and patient-to-patient variability was compared between two protocols using the Levene test. RESULTS The mean of EUBSA and EUBW were 0.0621 g I/m2/HU and 0.00178 g I/kg/HU for the aorta, and 0.342 g I/m2/HU and 0.00978 g I/kg/HU for the liver parenchyma, respectively. In the aortic enhancement, EUBSA was almost constant regardless of BSA, and the mean absolute deviation of the EEV with the BSA protocol was significantly lower than that with the BW protocol (P<.001), although there was no significant difference between two protocols in the hepatic parenchymal enhancement (P=.92). CONCLUSION For the aortic enhancement, determining the contrast medium dose based on BSA was considered to improve patient-to-patient enhancement variability.

Principles and techniques of transcatheter embolotherapy for peripheral vascular lesions

Transcatheter embolotherapy (TCE), a common procedure for interventional radiologists, comprises transcatheter delivery of embolic agents into target vessels in order to eliminate lesions or lesion-associated symptoms. Good knowledge of delivery catheters and embolic agents is essential to optimize embolization techniques and to obtain the desired therapeutic outcomes. In this review, we describe the principles and techniques of TCE for peripheral arterial and venous lesions featuring visceral aneurysms, peripheral and pulmonary arteriovenous malformations (AVMs), and varicoceles.

Percutaneous sclerotherapy for venous malformations in the extremities: clinical outcomes and predictors of patient satisfaction.

The purpose of this study is to retrospectively evaluate the clinical outcomes and to identify the predictors ofpatient satisfaction after percutaneous sclerotherapy for venous malformations (VMs) in the extremities. A totalof 48 patients with VMs in the extremities over 10 years of age underwent sclerotherapy to relieve symptoms, such as pain, swelling, functional limitations, and cosmetic problems. Self-assessment questionnaires were sentto rate the degree of symptom improvement and level of satisfaction. Clinical and imaging data from medicalrecords were analyzed to obtain information about VMs and sclerotherapy. The predictors for patientsatisfaction were determined by univariate and multivariate analysis of clinical variables. Forty patients (meanage, 28.2 years; range, 11-69 years) responded to the survey. Sixteen patients had VMs in the upper extremities, and 24 patients had VMs in the lower extremities. In 12 patients (30%), adjacent bone change was seen. After amean of 2.6 (range 1-10) sclerotherapy sessions, good response to pain, swelling, dysfunction, and cosmeticproblems was obtained in 83%, 74%, 79%, and 50% of patients, respectively. Thirty-two patients (80%) weresatisfied with their outcomes. On univariate analysis, absence of adjacent bone change, maximum diameter (<6.7 cm), and number of sclerotherapy sessions (<3) were significantly associated with patient satisfaction.Multivariate analysis revealed absence of adjacent bone change (odds ratio, 7.56; 95% confidence interval, 1.02-55.8) as an independent predictor for satisfaction. Thus, adjacent bone change significantly portended adissatisfied patient. In conclusion, percutaneous sclerotherapy was effective to relieve symptoms of VMs in theextremities, and most patients were satisfied with the outcomes. However, adjacent bone change was asignificant predictor of patient dissatisfaction.