Properties of N-butyl cyanoacrylate-iodized oil mixtures for arterial embolization: in vitro and in vivo experiments.

PURPOSE: To examine the properties of N-butyl cyanoacrylate (NBCA) and iodized oil (lipiodol [Lip]) in vitro and in vivo for safe and effective embolization. MATERIALS AND METHODS: Viscosity, polymerization time, and diffusing capacity were evaluated according to the NBCA/Lip ratio in vitro. Additionally, the effect of the NBCA/Lip ratio on arterial embolization was evaluated in vivo; various ratios of NBCA/Lip were injected into the renal arteries of adult beagles, after which the embolization effect following transcatheter arterial embolization was quantitatively investigated histopathologically and using computed tomography (CT) volumetry. RESULTS: The viscosity of NBCA/Lip increased, polymerization time was prolonged, and diffusing capacity increased as the NBCA density decreased. As the NBCA density decreased, embolic material was recognized in smaller diameter arteries, and embolization of a larger vascular bed was accomplished. The NBCA/Lip mixture with a low density of NBCA was located more peripherally from the catheter tip, and embolization of more peripheral and smaller diameter arteries was achieved. CONCLUSIONS: The relationships of properties of NBCA/Lip in vitro and embolization effects in vivo of various ratios of NBCA/Lip were quantitatively examined and compared. The results of this study are useful for safe and effective embolization.

Endovascular aneurysmal models at the external iliac artery of dogs.

INTRODUCTION: Establishing an aneurysm model using simple and easy operative techniques is desirable to develop new endovascular treatment devices such as stent grafts. We developed an aneurysm model using the external iliac arteries (EIAs) of adult Beagles, a relatively large animal that we thought would be easy to handle, using simple and less complicated endovascular procedures. In addition, we evaluated the generated aneurysm model histologically and determined the factors that were necessary for creating more dilated aneurysms. METHODS: Experimental animals consisted of 16 beagles (average weight, 14.0 kg). The animals were divided into four groups (S, E, B+S, and B+E). Eight Beagles were in the S and E groups, without balloon dilation. S group Beagles were injected with normal saline into the right EIA and served as a control group. Elastase was injected into the left EIA of the same Beagles (E group). Eight Beagles were in the B+S and B+E groups with balloon dilation. After balloon dilation, normal saline was injected into right EIA of the B+S group. Elastase was injected into the left EIA of the same Beagles (B+E). After 4 weeks, we measured the EIA diameter using abdominal ultrasound imaging from a body surface. Both sides of the EIA were harvested. We evaluated the dilation rate of the EIA diameter, and histologically, evaluated the disappearance of the internal elastic lamina, degeneration and disappearance of medial smooth muscle and the external elastic lamina, and neointimal thickening. RESULTS: Inner diameters were dilated more in the B+E group vs the other groups. The B+E group internal elastic lamina had almost disappeared, with significantly more severe degeneration and disappearance of external elastic lamina. CONCLUSIONS: We developed a muscular artery aneurysm model using the EIA arteries of adult Beagles and a simple endovascular procedure. Histologically, internal and external elastic lamina degeneration was an important factor to create significantly dilated aneurysms in this muscular artery model.

The fatal risk in hepatic artery embolization for hemostasis after pancreatic and hepatic surgery: importance of collateral arterial pathways.

PURPOSE: To assess retrospectively the cause of hepatic failure related to hepatic arterial embolization (HAE) for hemostasis after pancreaticoduodenectomy or hepatic lobectomy. MATERIALS AND METHODS: Between June 1993 and March 2006, Twenty HAEs in 17 patients (15 men, two women; mean age, 64 years) were performed. Angiographic findings, including portal vein stenosis, collateral arterial pathways after HAE, and the difference of embolic materials, were recorded. The morbidity (hepatic failure and abscess) and mortality were detailed according to collateral arterial pathways, portal vein stenosis, and embolic material used. RESULTS: Bleeding was controlled in all patients, although two patients required repeat embolization. Hepatic failure (n = 8) and abscess (n = 2) arose in nine of 20 HAEs. Death occurred after six of eight HAEs complicated by hepatic failure. The morbidity and mortality rates of HAE were 45% and 30%, respectively. Hepatic complication was eight times more likely to occur (P = .005) in cases with no hepatic collaterals involving hepatic, replaced, or accessory hepatic arteries. Death was observed only in the cases without hepatic collaterals (P = .011). The correlation between the embolization outcome and the presence of portal vein stenosis or the difference of embolic materials was not significant (P > .61). CONCLUSIONS: HAE can be used to successfully control bleeding secondary to hepatic arterial rupture. In the absence of hepatic collaterals, collateral circulation distal to the occlusion from nonhepatic sources may be inadequate and lead to hepatic failure after HAE.

Treatment of in-stent restenosis with beraprost sodium: an experimental study of short- and intermediate-term effects in dogs.

1. The aim of the present study was to evaluate the inhibitory effects of the short-term administration of beraprost sodium, a stable prostaglandin I(2) analogue, on neointimal thickening after stenting. 2. To examine the immediate and short-term effects, Z-stents were placed in the iliac veins of 12 dogs, which were randomly assigned to either a beraprost-treated or control (saline) group. Beraprost (0.35 microg/kg per min) or saline (1.5 mL/min) was administered 30 min before stenting and was continued for 5 h thereafter. Platelet aggregation was measured before and after drug administration. At 3, 7 and 14 days after stenting, dogs were killed and immunohistochemical staining for proliferating cell nuclear antigen was used to quantify the proliferation of vascular smooth muscle cells (SMC). To evaluate intermediate-term effects, a Z-stent was placed in the right iliac vein in 10 dogs, followed by beraprost treatment. Three days later, a second Z-stent was placed contralaterally with saline infusion as a control. After 4 weeks, dogs were killed and neointimal thickness was measured under a light microscope to calculate the intima : media area ratio. 3. Platelet aggregation was more significantly suppressed in the beraprost-treated than in the control group (P = 0.01). In addition, SMC proliferation was significantly lower in the beraprost-treated group 7 and 14 days after stenting (P < 0.05). Over the intermediate term, the intima : media area ratio was significantly lower in the beraprost-treated vein compared with control (P < 0.05). 4. In conclusion, short-term beraprost treatment during stenting suppresses in situ platelet aggregation and SMC proliferation, thus reducing neointimal thickening.

Evaluation of self-expandable, FK506-coated, covered stents in canine animal model.

This study aimed to evaluate whether drug coating of the recently developed covered SENDAI stents--self-expandable stents covered with segmented polyurethane (SPU) films--reduces neointimal thickening in animal model. FK506, which is one of the most effective immunosuppressants, was used. Bare stents; non-coated, covered stents; and FK506-coated, covered stents were placed bilaterally in the external iliac arteries of beagle dogs. After 1-month observation period, angiography did not show significant stent-induced stenosis. Histological evaluation revealed a completely endothelialized intravascular lumen and the absence of thrombus formation. The area of the intimal thickening induced by the FK506-coated stents was significantly smaller than that induced by the non-coated stents, whereas it was larger in the case of both the covered stents than that in the case of the bare stent. In conclusion, FK506 treatment of the self-expandable, covered stents was confirmed to effectively inhibit intimal thickening, although the SPU film used for covering functioned as a drug carrier in addition to a scaffold for intimal formation.

Correct diagnosis of vascular encasement and longitudinal extension of hilar cholangiocarcinoma by four-channel multidetector-row computed tomography.

Accurate diagnosis of local invasion of hilar cholangiocarcinomas is challenging due to their small size and the anatomic complexity of the hepatic hilar region. On the other hand, the correct diagnosis of local invasion is essential for assuring the possibility of curative surgery. The purpose of this study was to evaluate the feasibility of four-channel multidetector-row computed tomography (MDCT) in the assessment of vascular and bile duct involvement, by which we could obtain useful information for the surgical management of hilar cholangiocarcinoma. The subjects were 18 patients for whom the extent of tumor invasion was surgically and pathologically confirmed. All patients underwent preoperative multiphasic CT scanning by MDCT. Arterial and portal dominant phases were acquired using a detector configuration of 1.25 mm X 4 mm, and both axial and multiplanar reconstructed images were interpreted. Longitudinal extension was evaluated up to second-order branches. Vascular invasion is considered to be the degree of tumor contiguity to the hepatic arteries and portal vein and was graded by CT. The longitudinal extension was correctly diagnosed in 14 patients (77.8%). Hepatic artery invasion was correctly diagnosed in 17 patients with sensitivity of 100% and specificity of 90%, respectively. Portal vein invasion was correctly diagnosed in 47 of 51 branches with sensitivity and specificity of 92.3% and 90.2%, respectively. Multiplanar reconstructed images contributed to the correct diagnosis for both vascular encasement and longitudinal tumor extension. In conclusion, MDCT is useful in preoperative evaluation of hilar cholangiocarcinoma, especially when combined with multiplanar reconstructed images.

Differentiation of pathologic subtypes of papillary renal cell carcinoma on CT.

OBJECTIVE: We reviewed the CT findings of the subtypes of papillary renal cell carcinoma (RCC), which behave differently clinicopathologically. CONCLUSION: The CT features of the two pathologic subtypes of papillary RCC differ, probably reflecting their different pathologic features. Type 1 tumors have more distinct margins than type 2 tumors and have homogeneous density. Although type 2 tumors in the early stages show findings similar to those of type 1 tumors, they are at more advanced stages on the whole, with CT features showing indistinct margins, frequent centripetal infiltration, and tumor thrombi in all pT3b cases. Radiologists should be familiar with the CT features of papillary RCC that suggest different pathologic behaviors, such as tumor stage, tumor proliferation, and microvascular or vascular invasion.

Development of self-expandable covered stents.

We newly developed self-expandable covered stents by combining two of our original technologies. Of these, the first is the dip-coating covering method that was developed previously for balloon-expandable stents; the other is the newly developed self-expandable Nitinol stents, namely, Sendai stents. The three types of covered stents with the expansion diameter of 4.5, 5.0, or 6.0 mm thus obtained had a laser-processed microporous elastomeric cover film (pore diameter: 100 microm, interpore distance: 250 microm). Although the film was extremely thin (approximately 15 microm), the film could be expanded without causing any damage, the strut was completely embedded within the film, and the luminal surface of the film was smooth and flat. Mechanical properties such as ideal flexibility to follow the shapes of arteries were almost retained even after covering. As appropriate drugs, the blood-contacting inner and tissue-contacting outer surfaces of the film were differentially coated with argatroban for antithrombogenicity or FK506 for anti-inflammation, respectively. The preliminary in vivo study indicated that the covered stents mounted in the delivery catheter were navigated and placed to appropriate position in the arteries, and permissible neointimal thickening after 1-month implantation was observed similarly in noncovered stents.

Primary aldosteronism: a pictorial essay.

Primary aldosteronism is defined as secondary hypertension accompanied by aldosterone hypersecretion that leads to suppressed plasma renin, hypokaremia and hypertension. Primary aldosteronism occurs in 3-15% of hypertensive patients and is commonly caused by aldosterone-producing adenoma (APA) or bilateral idiopathic hyperaldosteronism (IHA). APA is usually treated by adrenalectomy, whereas IHA is best managed medically. Therefore, it is important to distinguish between unilateral and bilateral disease. Computed tomography (CT) is used to differentiate the subtypes. Even when multidetector CT is used, the detection rate of APAs of 1 cm or less is lower than 60% for the following reasons: (a) aldosterone secretion does not depend on tumor size, (b) a tumor may exist without lipid-rich cells, and (c) non-functioning unilateral adenomas are not uncommon, especially in older patients. Adrenal venous sampling is the gold standard for the differentiation of unilateral from bilateral disease in patients with primary aldosteronism. It is important to compare the laterality of aldosterone secretion by performing simultaneous bilateral blood collection 15 min following adrenocorticotropic hormone stimulation. The value of (aldosterone/cortisol)(side)/(aldosterone/cortisol)(contralateral side) provides the best discrimination between patients with and without APA.

Time-related changes in computed tomographic appearance and pathologic findings after radiofrequency ablation of the rabbit lung: preliminary experimental study.

PURPOSE: To evaluate correlations between computed tomographic (CT) appearance and pathologic findings after radiofrequency (RF) ablation of lungs and to determine whether CT appearance could predict the extent of the effective therapeutic area. MATERIALS AND METHODS: The lungs of 14 rabbits were subjected to RF ablation and CT scans were obtained immediately and at various intervals thereafter. Four rabbits were killed immediately after the initial CT imaging (n = 4). The remaining 10 rabbits were killed after additional CT scans at intervals of 3 days (n = 2), 1 week (n = 4), 2 weeks (n = 2), and 3 weeks (n = 2) after RF ablation. Pathologic findings were correlated with CT appearance. RESULTS: Immediately after RF ablation, a restricted area of central dense opacity enclosed by an extensive area of ground-glass opacity was noted in the ablated region on CT images. Pathologically, the former corresponded to destructive tissue and the latter corresponded to tissue with some degree of injury. After 1 week, the entire ablated region appeared as a well-demarcated homogeneous dense opacity on CT that corresponded to necrotic tissue and its surrounding rim of granulation tissue on histopathologic examination, indicating that the enclosing extensive area of ground-glass opacity on the initial CT scan represented an ongoing necrosis. Within 2-3 weeks, the ablated region gradually contracted on the CT images, representing a tissue repairing process in which the granulation tissue was encroaching on the inner necrotic tissue. CONCLUSION: Ground-glass opacity of the ablated region on CT immediately after RF ablation represents an ongoing necrosis.

Endovascular model of rabbit hindlimb ischemia: a platform to evaluate therapeutic angiogenesis.

PURPOSE: Current animal hindlimb ischemia models involve surgical ligation of the femoral artery and delivery of therapeutic angiogenic agents into the adductor compartment. The authors hypothesize that an endovascular model of hindlimb ischemia would be a more appropriate platform, closely resembling atherosclerosis by occluding the vessel from within, causing less inflammation, wound healing and subsequent collateralization. MATERIALS AND METHODS: The left superficial femoral artery in 17 rabbits was occluded by endovascular coil embolization (n=9) or surgical ligation (n=8). Animals (n=3; in each group) were sacrificed on day 3 to determine the arteriolar luminal area, number of arterioles, microsphere determined perfusion, and degree of inflammation. On day 28, the remaining animals underwent calf blood pressure measurements and angiography to determine the number of collaterals and diameter of vessels supplying the hindlimb. RESULTS: Immediate postprocedure (day 0) and presacrifice (day 3 or 28) occlusion rates were 89% (eight of nine rabbits) and 100% for the endovascular model; 100% and 100% for the surgical model, respectively. Hindlimb paralysis and muscle atrophy was found in one surgical animal. On day 3, there was an increase in hindlimb perfusion (surgery, 0.04+/-0.01; endovascular, 0.02+/-0.01; P=.02), an increase in arteriolar luminal area (surgery, 481 microm+/-240; endovascular, 345 microm+/-151; P=.04), and a trend toward more inflammation (surgery, 5.5+/-3.8; endovascular, 2.5+/-3.0; P=.08) in the surgical group. There was no difference in number of vessels between both groups. On day 28 there was no difference in the calf blood pressure ratios or in the number of collaterals. However, there was enlargement of the distal profunda femoris artery, the vessel closest to the surgical incision, in the surgical group (L/R ratio: immediate post-occlusion, 1.06+/-0.11; day 28, 1.27+/-0.08; P=.02). CONCLUSION: The endovascular model was efficacious in providing occlusion of the superficial femoral artery, and induced less of an arteriogenic response compared with the surgical model. The authors believe that this endovascular model is a superior platform for studying therapeutic angiogenic agents.

Low-dose CT of the thorax in cancer follow-up.

PURPOSE: To evaluate the quality of low-dose computed tomography (CT) images in the follow-up of cancer patients. MATERIALS AND METHODS: We selected patients with urogenital (n = 7) or esophageal cancer (n = 13) who were attending routine follow-up between April and July 2001. After water and chest phantom studies to decide the scan parameters, postcontrast low-dose CT scans were obtained at 60 mA (45 mA s) with a smoothing kernel. Three radiologists reviewed the CT scans of the thorax independently for overall image quality and anatomic detail in both mediastinal and lung windows. They subjectively rated the images on a four-point scale (0: poor, 1: fair, 2: good, 3: excellent) according to graininess and sharpness. RESULTS: The average score of the low-dose CT for the lung window was 2.85, which was equivalent to control images. The average score for the mediastinal window was 1.77, which was lower than that of the control CT scan (2.62, P < 0.001) and almost identical to that of the chest phantom experiment. Nine of the 20 cases had abnormal findings; low-dose CT scans depicted them well and offered sufficient information for diagnosis. The radiation exposure was reduced by about half. CONCLUSION: The image quality of low-dose thoracic CT was satisfactory for both mediastinal and lung windows in the follow-up of cancer patients.

Comparison of screen-film and full-field digital mammography in Japanese population-based screening.

PURPOSE: To investigate how the greater contrast of full-field digital mammography (FFDM) affects the detection of suspicious lesions in Japanese population-based screening. MATERIALS AND METHODS: Screen-film mammography (SFM) and FFDM were performed in 480 women aged 50 years or more. A set of mediolateral oblique views was obtained with each modality. All mammograms were independently double-read. The five-scale category assessment and type of finding using the Breast Imaging Reporting and Data system (BI-RADS) nomenclature were given. Intraobserver variance, recall rates, and positive predictive value were calculated. RESULTS: The findings between the two modalities were discordant. kappa-values for each reader were 0.619 and 0.385, respectively. Almost half of the microcalcifications were called with both modalities. The detection of masses was less concordant between the readers (27%). The masses were detected more frequently with FFDM (73%). Other findings were only detected with one modality. The recall rate was not significantly different (2.9% with SFM vs. 4.2% with FFDM; p=0.253). The positive predictive value was not significantly different (14% with SFM vs. 10% with FFDM; p=0.69), either. Two patients with breast cancer were detected with both modalities. CONCLUSION: Recall rates and positive predictive value were not significantly different between SFM and FFDM. Cancers were detected with both modalities.

Adrenal adenomas: relationship between histologic lipid-rich cells and CT attenuation number.

OBJECTIVE: To evaluate the relationship between lipid-rich cells of the adrenal adenoma and precontrast computed tomographic (CT) attenuation numbers in three clinical groups. MATERIALS AND METHODS: Thirty-five surgically resected adrenal adenomas were used. The clinical diagnoses of the patients included 13 cases of primary aldosteronism, 15 cases of Cushing's syndrome, and 7 non-functioning tumors. The number of lipid-rich clear cells was counted using a microscopic eyepiece grid that contained 100 squares. The results were expressed as the percentages of lipid-rich areas. RESULTS: There was a strong inverse linear relationship between the percentage of lipid-rich cells and the precontrast CT attenuation number (R(2)=0.724, P<0.0001). There were significantly more lipid-rich cells in the primary aldosteronism and non-functioning tumor cases compared to cases of Cushing's syndrome (P=0.007 and 0.015, respectively). The CT attenuation numbers of the primary aldosteronism cases were significantly lower than those of Cushing's syndrome (P=0.0052). Furthermore, the CT attenuation numbers of the non-functioning tumor cases were lower than those of Cushing's syndrome cases. CONCLUSION: We showed that adrenal adenomas in primary aldosteronism and non-functioning tumors contain significantly more lipid-rich cells than those in Cushing's syndrome. They also showed significantly lower attenuation than that in Cushing's syndrome on CT scans. Our results suggest that precontrast CT attenuation numbers may be helpful in the differentiation of adenomas from non-adenomatous lesions, which include malignancies.

Comparison of screen-film and full-field digital mammography: image contrast and lesion characterization.

PURPOSE: This study compared screen-film mammography (SFM) with full-field digital mammography (FFDM) of the same patients. MATERIALS AND METHODS: Twenty-four patients underwent surgery or biopsy, including 17 with carcinoma. Patients underwent both SFM and FFDM after providing informed consent. The abnormal findings consisted of 10 masses and 15 areas of microcalcification. The optical density of the breast tissue surrounding any lesion or mass was measured. Three readers evaluated the visibility of the masses and calcifications (contrast, margin, and type) by consensus from hard copies of the images. When evaluating FFDM, SFM was used as the standard of comparison. RESULTS: FFDM showed greater contrast of mass than SFM. The contrast of mass on FFDM was judged visually superior or equivalent to that of SFM, and microcalcifications were the same in most cases. The margin of the mass was better defined by FFDM in two cases. Determination of the type of microcalcification was similar for SFM and FFDM. CONCLUSION: FFDM provided greater contrast than SFM. FFDM might be helpful for detecting masses and observing their margins. Although FFDM may be of some use for detecting calcification, it has no advantage when determining the type of calcification.

Adrenal carcinoma with a signal loss on chemical shift magnetic resonance imaging.

A case of primary adrenal carcinoma that showed a decreased signal in part of the tumor on chemical shift magnetic resonance imaging (CSI) is reported. The patient had clinical symptoms of Cushing syndrome. The tumor was a discrete right adrenal mass about 3.4 cm in largest diameter. It was surgically removed and diagnosed as adrenal carcinoma histopathologically. Two portions where clear cells were prominent were recognized. These areas probably contributed to the signal loss on CSI.

Diffuse hepatic angiosarcoma with a portal venous supply mimicking hemangiomatosis.

We report a case of diffuse hepatic angiosarcoma. Dynamic computed tomography (CT) showed gradual contrast enhancement and homogeneity in the late phase. The tumor was homogeneously hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging, mimicking hemangiomatosis. An angiogram demonstrated intrahepatic arterial encasement, which suggested malignancy. The portal venous supply to the tumor was demonstrated by CT during arterioportography. This probably reflected the continuous infiltration of atypical cells into the dilating sinusoids and may also suggest malignancy.

Case report: chronic expanding hematoma in the adrenal gland with pathologic correlations.

We report a case of chronic expanding hematoma in the adrenal gland. Mixed signal intensity in a mosaic pattern was seen on T2-weighted images. A focal area suggesting a subacute hematoma was also noted. The dynamic CT scan showed heterogeneous contrast enhancement in the arterial phase and heterogeneous spread of the enhanced area within the tumor. Awareness of this finding may prevent the misdiagnosis of a tumor as a neoplastic intratumoral hemorrhage.