Location of embolization affects patency after coil embolization for pulmonary arteriovenous malformations: importance of time-resolved magnetic resonance angiography for diagnosis of patency.

OBJECTIVES: This study aimed to assess the diagnostic accuracy of computed tomography (CT) and time-resolved magnetic resonance angiography (TR-MRA) for patency after coil embolization of pulmonary arteriovenous malformations (PAVMs) and identify factors affecting patency. METHODS: Data from the records of 205 patients with 378 untreated PAVMs were retrospectively analyzed. Differences in proportional reduction of the sac or draining vein on CT between occluded and patent PAVMs were examined, and receiver operating characteristic analysis was performed to assess the accuracy of CT using digital subtraction angiography (DSA) as the definitive diagnostic modality. The accuracy of TR-MRA was also assessed in comparison to DSA. Potential factors affecting patency, including sex, age, number of PAVMs, location of PAVMs, type of PAVM, and location of embolization, were evaluated. RESULTS: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CT were 82%, 81%, 77%, 85%, and 82%, respectively, when the reduction rate threshold was set to 55%, which led to the highest diagnostic accuracy. The sensitivity, specificity, PPV, NPV, and accuracy of TR-MRA were 89%, 95%, 89%, 95%, and 93%, respectively. On both univariable and multivariable analyses, embolization of the distal position to the last normal branch of the pulmonary artery was a factor that significantly affected the prevention of patency. CONCLUSIONS: TR-MRA appears to be an appropriate method for follow-up examinations due to its high accuracy for the diagnosis of patency after coil embolization of PAVMs. The location of embolization is a factor affecting patency. KEY POINTS: • Diagnosis of patency after coil embolization for pulmonary arteriovenous malformations (PAVMs) is important because a patent PAVM can lead to neurologic complications. • The diagnostic accuracies of CT with a cutoff value of 55% and TR-MRA were 82% and 93%, respectively. • The positioning of the coils relative to the sac and the last normal branch of the artery was significant for preventing PAVM patency.

Non-contrast computed tomography and magnetic resonance imaging features of mucoepidermoid carcinoma in the salivary glands.

BACKGROUND: Use of contrast-enhanced cross-sectional imaging is considered standard practice for investigating mucoepidermoid carcinoma (MEC) in the salivary glands. The purpose of this study was to present the common features of MEC on computed tomography (CT) and magnetic resonance imaging (MRI) without contrast enhancements, and to investigate the possibility of discriminating between MEC and pleomorphic adenoma based on the features observed on both modalities. METHODS: Twenty cases of biopsy-confirmed MEC originating in the salivary glands were reviewed and characterized by two oral and maxillofacial radiologists with regard to the following aspects: detectability, margin, border, encapsulation, content, contrast between lesion and masticator muscle, and bone changes. RESULTS: Ninety percent of bone changes caused by MEC were detected by CT and sixty-nine percent of tumor existences were detected by MRI. The lesion border could provide a clue to distinguish MEC from pleomorphic adenoma. CONCLUSIONS: Observation of MEC features was possible by both CT and MRI. Among the features, the lesion border could be a clue to distinguish MEC from pleomorphic adenoma.

Long-Term Outcomes of Selective Renal Artery Embolization for Renal Arteriovenous Fistulae with Dilated Venous Sac.

PURPOSE: To retrospectively evaluate the role of selective renal artery embolization for renal arteriovenous fistulae (AVFs) with dilated venous sac. MATERIALS AND METHODS: Between 2002 and 2015, 14 patients (7 men and 7 women; mean age, 60 years) with a single renal AVF with dilated venous sac underwent selective renal artery embolization. Three patients presented with gross hematuria, 4 presented with occult blood in urine, and 1 presented with chronic heart failure. Five patients had a history of renal biopsy or partial nephrectomy. Embolic agents used included pushable fibered coils, detachable microcoils, hydrogel coils, N-butyl 2-cyanoactylate, and/or absolute ethanol. Technical success was defined as complete angiographic occlusion of the renal AVF without visualization of the venous sac. Clinical success was defined as the disappearance of the AVF on ultrasound and contrast-enhanced computed tomography, without any symptoms. RESULTS: Fifteen sessions of selective renal artery embolization were performed. Technical success was achieved in 13 sessions (86.7%). Clinical success was achieved in 13 patients (92.9%) after a mean follow-up of 48 months (range, 6-155 months). Two major complications occurred-renal vein thrombosis (n = 1) and renovascular hypertension (n = 1)-and were successfully managed with warfarin and an angiotensin-II receptor blocker, respectively. The former patient required re-embolization because of recanalization. No significant changes were observed in the mean serum creatinine level (.86 mg/dL vs .85 mg/dL; P = .67) and the mean estimated glomerular filtration rate (66.0 mL/min/1.73m2 vs 67.4 mL/min/1.73m2; P = .4) after 6 months. CONCLUSIONS: Selective renal artery embolization is a safe and effective treatment for renal AVFs with dilated venous sac.

Subclassification of patients with intermediate-stage (Barcelona Clinic Liver Cancer stage-B) hepatocellular carcinoma using the up-to-seven criteria and serum tumor markers.

BACKGROUND: Intermediate-stage [Barcelona Clinic Liver Cancer stage-B (BCLC-B)] hepatocellular carcinoma (HCC) comprises of a heterogeneous population of patients with a wide range of tumor burdens. We therefore formulated a subclassification of BCLC-B HCC using the up-to-seven criteria and tumor markers according to the results of a retrospective analysis of these patients. METHODS: This study included 125 patients newly diagnosed with BCLC-B HCC who underwent transarterial chemoembolization. Among them, 39 and 86 were within or beyond the up-to-seven criteria, respectively. Multivariate Cox proportional hazards analysis was performed to investigate factors that contributed to better prognosis associated with the criteria. RESULTS: Cumulative overall survival (OS) and disease-free survival rates were significantly higher for patients within the up-to-seven criteria compared with those beyond (p = 0.034 and p = 0.001, respectively). Multivariate analysis revealed that low concentrations of des-γ-carboxy prothrombin (DCP) (<150 mAU/ml) and α-fetoprotein (AFP) (<100 ng/ml) were independent contributors to better OS of patients within or beyond the up-to-seven criteria, respectively. Accordingly, the patients were classified as follows: group A (patients within the up-to-seven criteria with DCP <150 mAU/ml), group C (patients beyond the up-to-seven criteria with AFP ≥100 ng/ml), and group B (other patients). OS differed significantly among groups (p < 0.001), and the median survival times of group A, B, and C were 4.2, 2.7, and 1.5 years, respectively. CONCLUSION: The subclassification system incorporating the up-to-seven criteria combined with DCP and AFP levels may serve as better predictors of prognosis that may guide efforts to improve treatment strategies.

Analysis of Recurrence Patterns After Anatomical or Non-anatomical Resection for Hepatocellular Carcinoma.

BACKGROUND: Recurrence patterns after hepatic resection has been poorly understood in view of tumor blood flow drainage (TBFD) area. Our goal was to clarify the recurrence patterns after anatomical versus nonanatomical hepatic resection for hepatocellular carcinoma (HCC). METHODS: A total of 424 consecutive patients with HCC, who were treated by curative resection (R0) at our hospital from 2001 to 2012, were evaluated. Among these, we compared the outcomes of the anatomical resection group (AR group, n = 243) and the nonanatomical resection group (NR group, n = 181). We performed an analysis of the recurrence patterns of HCC based on the preoperative CT during hepatic arteriography in these 424 patients. RESULTS: Preoperative liver function was better in the AR group than the NR group (P < 0.001), and tumor size was larger in the AR group than the NR group (P < 0.001). HCC recurrence was recorded in 145 patients (59.7 %) of the AR group and 102 patients (56.4 %) of the NR group with no significant differences between the two groups (P = 0.590). The incidences of extrahepatic and intrahepatic recurrence (solitary/multiple) were similar between the two groups. In addition, the rate of recurrences by local dissemination, either recurrences in the same subsegment in the NR group or recurrences in the TBFD area in the AR group, was sufficiently low (1.4 %) as to be considered negligible. CONCLUSIONS: The incidence and patterns of HCC recurrence were similar between the anatomical and nonanatomical resection. Recurrence by local dissemination may be considered to be negligible in both surgical methods.

Computed tomography during hepatic arteriography pattern may predict hepatocellular carcinoma recurrence following transarterial chemoembolization.

AIM: This study aimed to determine the role of morphological patterns seen on imaging in predicting hepatocellular carcinoma recurrence following transarterial chemoembolization therapy. METHODS: Forty-seven patients from a single center who underwent transarterial chemoembolization to treat unresectable hepatocellular carcinomas between January 2011 and June 2012 were included in this study. We investigated whether the two pretreatment findings on computed tomography during hepatic arteriography (pattern 1, the single nodule pattern; pattern 2, at least one nodule showing the contiguous multinodular pattern) and other factors (age, sex, etiology, serum total bilirubin, serum albumin, prothrombin time, platelet count, serum level of protein induced by vitamin K absence/antagonist-II, serum α-fetoprotein, number of previous treatments for hepatocellular carcinoma, tumor number and maximum tumor size, presence of hypovascular lesions) could predict post-treatment recurrence. RESULTS: In a univariate analysis using Cox's proportional hazards model, serum total bilirubin, the serum level of protein induced by vitamin K absence/antagonist-II (≤100 vs ≥101 mAU/mL), tumor morphology (pattern 1 vs 2) and tumor number (≤3 vs ≥4) showed statistical significance (≤0.05). In a multivariate analysis of these factors, morphology and tumor number showed significance. According to Kaplan-Meier estimation, the cumulative disease-free survival rates were significantly lower in patients with four or more lesions than in those with three or less lesions and in patients showing pattern 2 than in those showing pattern 1. CONCLUSION: Patients with pattern 2 hepatocellular carcinoma and/or four or more lesions may have a relatively high recurrence rate after transarterial chemoembolization.

Initial experience with use of hydrogel microcoils in embolization of pulmonary arteriovenous malformations.

The purpose of this study is to describe our initial experience with embolization of pulmonary arteriovenous malformations (PAVMs) using hydrogel microcoils. The technical and radiological outcomes were retrospectively reviewed in seven patients with nine simple-type PAVMs (median feeder size 4 mm, range 3-6 mm) who underwent embolization. Hydrogel microcoils were mainly used, and detachable bare microcoils were combined as needed to occlude the terminal feeding artery just before the sac. Of a total of 43 microcoils, 30 (69.8%) hydrogel microcoils were deployed in eight PAVMs with the median number 3.5 (range 2 to 6) per lesion. All hydrogel microcoils were successfully deployed without microcatheter stuck or malposition. In the remaining one small PAVM, only soft bare microcoils were used, however, resulting in recanalization requiring additional coils in the second session. The venous sac was substantially shrunk in all lesions treated with hydrogel microcoils with the median size reduction rate 95.0% (range 81.8% to 99.0%) during the median follow-up period 10 months (range 6 to 18 months). In conclusion, hydrogel microcoils were safely and effectively applied for occluding PAVMs with relatively small feeders.

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.

In vivo evaluation of cisplatin-loaded superabsorbent polymer microspheres for use in chemoembolization of VX2 liver tumors.

PURPOSE: To investigate the pharmacokinetics and efficacy of chemoembolization with a cisplatin-loaded superabsorbent polymer (SAP) suspension in a rabbit model with transplanted liver VX2 tumors. MATERIALS AND METHODS: VX2 tumors were implanted into the left lobe of the liver in eight rabbits. Embolization of the proper hepatic artery was performed with cisplatin-loaded or unloaded SAP. In the cisplatin-loaded SAP group (n = 4), 5 mg of SAP (106-150 µm) loading 2.35 mg of cisplatin and 0.5 mL of ionic contrast material (ioxaglic acid 320 mgI/mL) was injected into the proper hepatic artery. In the control group (hepatic arterial infusion [HAI] + SAP; n = 4), 5 mg of SAP loading 0.5 mL of ioxaglic acid alone was injected after a bolus infusion of an equivalent amount of cisplatin. Sequential change of the plasma platinum concentration within the first 24 hours was measured. Blood sampling and histopathologic examination were performed at 1-week follow-up. Magnetic resonance (MR) images were used to calculate the growth rate of the VX2 tumor. RESULTS: All animals underwent successful embolization. Both total and free plasma platinum mean concentrations within the first 24 hours remained lower in the cisplatin-loaded SAP group, although without statistical significance (P > .05). The mean tumor growth rate was significantly lower in the cisplatin-loaded SAP group than the control group (20% vs 116%; P = .049). Histopathologic examination revealed coagulative necrosis to nontumorous liver parenchyma in two rabbits in the cisplatin-loaded SAP group, although no deaths occurred. CONCLUSIONS: These results suggested that chemoembolization with cisplatin-loaded SAP was a safe and tolerable treatment and was more effective in suppressing the tumor growth.

Transarterial chemoembolization with cisplatin as second-line treatment for hepatocellular carcinoma unresponsive to chemoembolization with epirubicin-Lipiodol emulsion.

PURPOSE: The purpose of this retrospective study was to investigate the efficacy of transarterial chemoembolization (TACE) using cisplatin as a second-line treatment for advanced hepatocellular carcinoma (HCC) unresponsive to TACE using epirubicin-Lipiodol emulsion at our institution. MATERIALS AND METHODS: Between January 2006 and March 2009, 51 patients with unresectable HCC underwent TACE using cisplatin. All patients had shown persistent viable tumor or tumor progression after at least 2 sessions of TACE using epirubicin-Lipiodol emulsion. TACE procedures consisted of arterial injection of a mixture of Lipiodol and cisplatin (30-100 mg [mean 57 ± 21]) (n = 29) or arterial infusion of cisplatin (30-100 mg [mean 87 ± 19]) solution (n = 22) followed by injection of 1-mm porous gelatin particles. Early tumor response was assessed by contrast-enhanced computed tomography (CT) according to Response Evaluation Criteria in Solid Tumors (RECIST) and European Association for the Study of the Liver (EASL) criteria. Overall survival and progression-free survival was calculated using the Kaplan-Meier method. Toxicity was assessed according to NCI-CTCAE version 3 criteria. RESULTS: Response rates were 11.8 and 27.5% by RECIST and EASL criteria, respectively. Overall survival rates were 61.9, 48.2, and 28.9% at 1, 2, and 3 years, respectively, and the median survival time was 15.4 months. Progression-free survival rate was 35.2% at 1 year, and median progression-free survival time was 3.1 months. No major complications were observed, and the occurrence of postembolization syndrome was minimal. Grade 3 to 4 toxicities included thrombocytopenia (5.8%), increased aspartate aminotransferase (AST) level (35.3%), and increased alanine aminotransferase (ALT) level (23.5%). CONCLUSION: Switching the TACE anticancer drug from epirubicin to cisplatin might be the feasible option for advanced HCC, even when considered resistant to the initial form of TACE.

Detection of pulmonary nodules by C-arm CT using a phantom lung: comparison with CT.

BACKGROUND: Evaluation of detection of lung nodules by C-arm CT (CACT) is important before this procedure can be used to guide percutaneous lung interventions. PURPOSE: To compare the efficacy of CACT with CT in the detection of pulmonary nodules using a phantom lung. MATERIAL AND METHODS: A phantom lung containing 12 phantom nodules in four sizes (5 mm/8 mm/10 mm/12 mm) and three CT values (one solid nodule, +100 HU; two ground glass nodules, -630 and -800 HU) was used. Six sessions of CACT (slice thickness 4.5 mm) and CT (slice thickness 5 mm) were performed. In each session, the locations of nodules were arbitrarily changed in the phantom. Three radiologists assessed the detection of a total of 72 nodules. Statistical analysis was performed for the sensitivity and positive predictive value of lung nodules between CACT and CT by the McNemar test and paired t-test (P < 0.05). RESULTS: Sensitivity did not differ between CACT and CT, respectively (reader 1, 82% vs. 88%, P = 0.22; reader 2, 82% vs. 78%, P = 0.37; reader 3, 79% vs. 83%, P = 0.48). For nodules of 8 mm or larger, the sensitivity increased for each reader and showed no significant difference between CACT vs. CT. The positive predictive value did not differ between CACT and CT. CONCLUSION: In this phantom study, CT and CACT show similar sensitivity for the detection of pulmonary nodules. CACT could be used in percutaneous interventional procedures in the lungs.

Lung perfused blood volume images with dual-energy computed tomography for chronic thromboembolic pulmonary hypertension: correlation to scintigraphy with single-photon emission computed tomography.

OBJECTIVE: The purpose of this study was to evaluate the feasibility and diagnostic utility of lung perfused blood volume (LPBV) images generated by dual-energy computed tomography (CT), as compared with pulmonary perfusion scintigraphy, for patients with chronic thromboembolic pulmonary hypertension. METHODS: Patients (n = 51) with chronic pulmonary thromboembolic embolism were examined by dual-source CT in dual-energy mode. Lung perfused blood volume images were generated by analysis of the iodine content of the lung parenchyma using dual-energy data. Pulmonary perfusion defects were evaluated on a segment-by-segment basis in images obtained by both LPBV and pulmonary scintigraphy. Findings suggestive of chronic thromboembolic pulmonary hypertension in CT pulmonary angiography were analyzed. RESULTS: All examinations were acquired without complications, and the contrast enhancement of the pulmonary artery was sufficient for diagnosis of vascular thromboses. In the LPBV images, in 76 (8.3%) of 918 segments, it was difficult to assess perfusion because of artifacts. The agreement between the 2 modalities was good (κ = 0.70). The sensitivity of LPBV in detecting perfusion defects was 96%; the specificity was 76%; the positive predictive value was 94%, and the negative predictive value was 29%. CONCLUSIONS: Lung perfused blood volume imaging by dual-energy CT is feasible for the evaluation of pulmonary perfusion and is comparable to pulmonary scintigraphy. It is possible to evaluate vessels and pulmonary perfusion with CT pulmonary angiography and LPBV images and to assess pulmonary perfusion more definitively in diagnosing chronic pulmonary thromboembolic embolism.

Assessment of calcified carotid plaque volume: comparison of contrast-enhanced dual-energy CT angiography and native single-energy CT.

OBJECTIVE: The purpose of this study was to compare estimates of calcified plaque volume in the carotid arteries based on contrast-enhanced dual-energy CT angiograms with volume estimates based on native CT scans. CONCLUSION: Detection of hard plaque in the carotid arteries with dual-energy CT angiography was successful in all patients. Estimates of calcified plaque volume based on dual-energy CT angiograms correlated well with those based on native single-energy CT scans but at a lower attenuation threshold (130 HU as opposed to 180 HU) were underestimates compared with those on the native CT scans.

Porous gelatin particles for uterine artery embolization: an experimental study of intra-arterial distribution, uterine necrosis, and inflammation in a porcine model.

PURPOSE: We evaluated the location of porous gelatin particles (GP; Gelpart; Nippon Kayaku/Astellas, Tokyo, Japan) within the arterial vasculature and their acute effects on uterine necrosis and inflammation after uterine artery embolization (UAE) in swine. MATERIALS AND METHODS: Adult nonpregnant pigs (n = 6) were allocated to either 1- (n = 3) or 2-mm GP (n = 3). Superselective and bilateral embolization of the uterine arteries was performed. All animals were killed 1 week after UAE. Macroscopic and microscopic findings, including the level of arterial occlusion and their effect on uterine necrosis and inflammation, were analyzed. RESULTS: All UAE procedures were completed without severe complications. The macroscopic necrosis was seen in two animals in the 2-mm group with an extent of <50%. The location of the occluded arteries did not differ significantly between groups. The median diameters of the occluded arteries were 449 microm (95% confidence interval [CI] 417-538 microm) in the 1-mm GP group and 484 microm (95% CI 370-560 microm) in the 2-mm GP group. As for microscopic necrosis, no statistically significant difference was observed. The qualitative inflammatory reaction was significantly greater in the 2-mm GP group than in the 1-mm group (p < 0.001). CONCLUSIONS: Both 1- and 2-mm GP occluded the arteries relevant to the target diameter for UAE in porcine uterus, presumably due to the plastic deformity. Both sizes of GP were associated with limited areas of necrosis; however, evaluation of inflammatory reaction was preliminary. Further study with adequate evaluation of inflammatory reactions is suggested.

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.

Dual-energy CT head bone and hard plaque removal for quantification of calcified carotid stenosis: utility and comparison with digital subtraction angiography.

We evaluated quantification of calcified carotid stenosis by dual-energy (DE) CTA and dual-energy head bone and hard plaque removal (DE hard plaque removal) and compared the results to those of digital subtraction angiography (DSA). Eighteen vessels (13 patients) with densely calcified carotid stenosis were examined by dual-source CT in the dual-energy mode (tube voltages 140 kV and 80 kV). Head bone and hard plaques were removed from the dual-energy images by using commercial software. Carotid stenosis was quantified according to NASCET criteria on MIP images and DSA images at the same plane. Correlation between DE CTA and DSA was determined by cross tabulation. Accuracies for stenosis detection and grading were calculated. Stenosis could be evaluated in all vessels by DE CTA after applying DE hard plaque removal. In contrast, conventional CTA failed to show stenosis in 13 out of 18 vessels due to overlapping hard plaque. Good correlation between DE plaque removal images and DSA images was observed (r (2) = 0.9504) for stenosis grading. Sensitivity and specificity to detect hemodynamically relevant (>70%) stenosis was 100% and 92%, respectively. Dual-energy head bone and hard plaque removal is a promising tool for the evaluation of densely calcified carotid stenosis.

Dual-energy direct bone removal CT angiography for evaluation of intracranial aneurysm or stenosis: comparison with conventional digital subtraction angiography.

Dual-energy CT can be applied for bone elimination in cerebral CT angiography (CTA). The aim of this study was to compare the results of dual-energy direct bone removal CTA (DE-BR-CTA) with those of digital subtraction angiography (DSA). Twelve patients with intracranial aneurysms and/or ICA stenosis underwent a dual-source CT in dual-energy mode. Post-processing software selectively removed bone structures using the two energy data sets. Three-dimensional images with and without bone removal were reviewed and compared to DSA. Dual-energy bone removal was successful in all patients. For 10 patients, bone removal was good and CTA maximum-intensity projection (MIP) images could be used for vessel evaluation. For two patients, bone removal was moderate with some bone remnants, but this did not inhibit the three-dimensional visualization. Three aneurysms adjacent to the skull base were only partially visible in conventional CTA but were fully visible in DE-BR-CTA. In five patients with ICA stenosis, DE-BR-CTA revealed the stenotic lesions on the MIP images. The correlation between DSA and DE-BR-CTA was good (R (2)=0.822), but DE-BR-CTA led to an overestimation of stenosis. DE-BR-CTA was able to eliminate bone structure using only a single CT data acquisition and is useful to evaluate intracranial aneurysms and stenosis.

Effects of low-dose, intermittent treatment with recombinant human parathyroid hormone (1-34) on chondrogenesis in a model of experimental fracture healing.

Recent studies have demonstrated that intermittent administration of parathyroid hormone (PTH) enhances osteogenesis (hard callus formation) and increases mechanical strength in experimental fracture healing. Thus far, however, effects of PTH on chondrogenesis (soft callus formation) during fracture healing have not been fully elucidated. In the present study, we analyzed the underlying molecular mechanism by which exogenous PTH would affect chondrogenesis in a model of experimental fracture healing. Unilateral femoral fractures were produced in 2-month-old Sprague-Dawley rats. Daily subcutaneous injections of 10 microg/kg of recombinant human PTH(1-34) [rhPTH(1-34)] were administered over a 28-day period of fracture healing. Control animals were injected with vehicle solution (normal saline) alone. The results showed that, on day 14 after fracture, cartilage area in the PTH-treated group was significantly increased (1.4-fold) compared with the controls, but this increase was not observed at days 21 and 28. In the early stage of chondrogenesis (days 4-7), cell proliferation, expressed as the rate of proliferating cell nuclear antigen-positive cells, was increased in mesenchymal (chondroprogenitor) cells but not chondrocytes in the PTH-treated group compared with controls. In addition, gene expression of SOX-9 was up-regulated in the PTH-treated group on day 4 (1.4-fold), and this was accompanied by enhanced expression of pro-alpha1 (II) collagen (1.8-fold). After 14 days, there were no significant differences between groups in either cell proliferation or the expression levels of cartilage differentiation-related genes (SOX-9, pro-alpha1 (II) collagen, pro-alpha1 (X) collagen and osteopontin). These results suggest that intermittent treatment with low-dose rhPTH(1-34) induces a larger cartilaginous callus but does not delay chondrocyte differentiation during fracture healing.

Gene expression of periostin in the early stage of fracture healing detected by cDNA microarray analysis.

To comprehensively evaluate gene expression in the early stage of fracture healing, we used a cDNA microarray with 2304 cDNA clones derived from an oligo-capped mouse embryo library. Closed mid-diaphyseal fractures were created in mouse tibiae and expression profiles were analyzed 3 days after fracture. Six genes were up-regulated in comparison to those in unfractured bones and these included three genes previously identified but never shown to be present in fractures, periostin, calumenin, and FHL-1. Cloning of these genes has been completed but their expression pattern and function during fracture healing and bone formation remain to be elucidated. Up-regulation of the six genes was reconfirmed by semi-quantitative RT-PCR analysis. Spatial and temporal expression of one of the newly identified fracture-induced genes, periostin, was analyzed using in situ hybridization, because it displayed the highest up-regulation ratio. A signal for periostin was detected in undifferentiated mesenchymal cells and immature preosteoblastic cells in the periosteal tissues between days 3 and 14 after fracture. Northern analysis showed that periostin gene expression rapidly increased by day 3, reached a peak on day 7, and declined by day 14. These findings suggest that periostin is a specific marker for preosteoblasts and may play an important role in periosteal callus formation during the early stage of fracture healing.