Risk factors for severity of pneumothorax after CT-guided percutaneous lung biopsy using the single-needle method.

The purpose of this study is to evaluate the risk factors for the severity of pneumothorax after computed tomography (CT)-guided percutaneous lung biopsy using the single-needle method. We reviewed 91 biopsy procedures for 90 intrapulmonary lesions in 89 patients. Patient factors were age, sex, history of ipsilateral lung surgery and grade of emphysema. Lesion factors were size, location and pleural contact. Procedure factors were position, needle type, needle size, number of pleural punctures, pleural angle, length of needle passes in the aerated lung and number of harvesting samples. The severity of pneumothorax after biopsy was classified into 4 groups: "none", "mild", "moderate" and "severe". The risk factors for the severity of pneumothorax were determined by multivariate analyzing of the factors derived from univariate analysis. Pneumothorax occurred in 39 (43%) of the 91 procedures. Mild, moderate, and severe pneumothorax occurred in 24 (26%), 8 (9%) and 7 (8%) of all procedures, respectively. Multivariate analysis showed that location, pleural contact, number of pleural punctures and number of harvesting samples were significantly associated with the severity of pneumothorax (p < 0.05). In conclusion, lower locations and non-pleural contact lesions, increased number of pleural punctures and increased number of harvesting samples presented a higher severity of pneumothorax.

Visceral fat accumulation as a predictor of coronary artery calcium as assessed by multislice computed tomography in Japanese patients.

The impact of visceral adiposity on subclinical coronary atherosclerosis is unclear in Japanese patients. We investigated the sex-specific relationship between the amount of visceral fat and coronary artery calcium (CAC) using multislice computed tomography (MSCT). This is a cross-sectional study of 321 consecutive Japanese patients (213 men and 108 women) who underwent MSCT scanning for the examination of coronary heart disease. CAC score, visceral fat area (VFA), subcutaneous fat area (SFA), and waist circumference (WC) were determined by MSCT for all patients. The prevalence of detectable CAC was 73% and 57% in men and women, respectively. Using a multivariable logistic and ordinal regression analyses adjusting for traditional cardiovascular risk factors and adiposity measurements, VFA represented an independent predictor of the presence and extent of CAC (odds ratio (95% confidence interval) per one-unit-standard deviation increase in VFA: 2.48 (1.23-6.05) in logistic regression analysis; 2.05 (1.18-3.98) in ordinal regression analysis). Similar relationships were observed across the gender. We further assessed the sex-specific cut-off levels of VFA and WC to predict the presence of CAC. The results of receiver operator characteristic analysis indicated that the VFA cut-off level in men was 116cm(2); and in women, it was 82cm(2), corresponding to WC values of 87.7cm in men and 82.6cm in women. In conclusion, we found that visceral adiposity measured by MSCT is significantly associated with the presence and extent of CAC as a marker of subclinical atherosclerosis in Japanese patients.

Prospective versus retrospective ECG-gated 64-detector coronary CT angiography: assessment of image quality, stenosis, and radiation dose.

PURPOSE: To show that prospective electrocardiographically (ECG)-triggered coronary computed tomographic (CT) angiography (hereafter, prospective CT angiography) is at least as effective as retrospective ECG-gated coronary CT angiography (hereafter, retrospective CT angiography). MATERIALS AND METHODS: Institutional review committee approval and informed consent were obtained. Sixty patients with heart rates of less than 75 beats per minute who were referred for coronary CT angiography were enrolled. Both prospective and retrospective CT angiography were performed with a 64-detector scanner. Data acquisition times were recorded. Two independent cardiac radiologists evaluated subjective image quality (1, excellent; 4, poor) and severity of stenosis (0% occlusion, 1%-49% occlusion, 50%-75% occlusion, and >75% occlusion) with the 17-segment American Heart Association classification model. Discrepancies were settled by consensus. Effective radiation doses of prospective and retrospective CT angiography were calculated with volume CT dose index. Data regarding acquisition time and radiation exposure for prospective and retrospective CT angiography were compared. The Student t test was performed, and kappa statistics were calculated. RESULTS: Mean data acquisition time of prospective CT angiography was shorter than that of retrospective CT angiography (5.6 seconds +/- 1.1 [standard deviation] vs 6.7 seconds +/- 1.1, respectively; P < .01). Consensus-determined image quality in coronary artery branches was similar between prospective CT angiography and retrospective CT angiography (1.15 vs 1.13, respectively; P = .992). Excellent agreement between prospective CT angiography and retrospective CT angiography was observed in the detection of significant (>or=50% occlusion) coronary artery stenoses per segment (kappa = 0.882) and in the grading of stenoses per patient (kappa = 0.829). Calculated effective dose with prospective CT angiography was 79% lower than that with retrospective CT angiography (4.1 mSv +/- 1.8 vs 20.0 mSv +/- 3.5, respectively; P < .001). CONCLUSION: Prospective CT angiography can reduce radiation dose below that of retrospective CT angiography with dose modulation, while maintaining image quality and the ability to assess luminal obstructions in patients with heart rates of less than 75 beats per minute.

Optimal cardiac phase for coronary artery calcium scoring on single-source 64-MDCT scanner: least interscan variability and least motion artifacts.

OBJECTIVE: The purpose of our study was to investigate the cardiac phase with the least interscan variability and motion artifacts on coronary artery calcium studies using a 64-MDCT scanner. SUBJECTS AND METHODS: Ninety-one patients with suspected coronary artery disease were scanned twice on retrospective ECG-gated helical scans. Images with 2.5-mm thickness and 1.25-mm interval at nine cardiac phases (center of cardiac phase: 40-80% in 5% increments) were reconstructed. The interscan variability of coronary artery scores (Agatston, volume, and mass) per patient and motion artifact scores per branch, subjectively assigned by motion artifact grading (1, none; 2, minor; and 3, major), were compared between cardiac phases for all patients, low (< 65 beats per minute [bpm]) and high (>or= 65 bpm) heart rate patient groups. RESULTS: For all patients, two-factor factorial analysis of variance revealed that the interscan variability was different between cardiac cycles (p < 0.01); however, this was not statistically significant between scoring algorithms (p = 0.46). The least variability was obtained at 70% on Agatston (8%) and volume (7%) and at 75% on mass (7%). Adjacent categories logit model analysis revealed that the motion artifact score was the least at 75% (left anterior descending coronary artery, 1.3; left circumflex coronary artery, 1.4; and right coronary artery, 1.9 in all patients) and that a smaller difference in calcium scores between the scans led to a smaller motion artifact score (p < 0.05). CONCLUSION: Middiastole reconstruction (center of cardiac phase: 70-75%), with the least interscan variability and the least motion artifacts, is recommended on 64-MDCT.

Variability of repeated coronary artery calcium measurements by 1.25-mm- and 2.5-mm-thickness images on prospective electrocardiograph-triggered 64-slice CT.

High reproducibility on coronary artery calcium scoring is a key requirement in monitoring the progression of coronary atherosclerosis. The purpose of this prospective study is to assess the reproducibility of 1.25-mm- and 2.5-mm-thickness images on prospective electrocardiograph-triggered 64-slice CT with respect to 2.5-mm-thickness images on spiral overlapping reconstruction. One hundred patients suspected of coronary artery disease were scanned twice repeatedly, both on prospective electrocardiograph-triggered step-and-shoot and retrospective electrocardiograph-gated spiral scans. Using 1.25-mm-thickness collimation, 1.25-mm- and 2.5-mm-thickness image sets on prospective scans and 2.5-mm-thickness image sets with 1.25-mm increment (overlapping) on retrospective scans were obtained. Coronary artery calcium scores, interscan variability and interobserver variability were evaluated. The mean interscan variability in coronary artery calcium measurement on 1.25-mm prospective/2.5-mm prospective/2.5-mm overlapping retrospective scans were Agatston: 10%/18%/12%, volume: 10%/12%/10% and mass: 8%/13%/11% for observer 1 and Agatston: 8%/14%/10%, volume: 7%/9%/10% and mass: 7%/10%/9% for observer 2, respectively. The mean interobserver variability was 5% to 14%. In conclusion, prospective electrocardiograph-triggered 64-slice CT using the 1.25-mm prospective scan shows the lowest variability. The 2.5-mm prospective scan on volume or mass scoring shows variability of around 10%, comparable to 2.5-mm-thickness spiral overlapping reconstruction images.

Usefulness of measuring coronary lumen density with multi-slice computed tomography to detect in-stent restenosis.

BACKGROUND: A method to objectively detect in-stent restenosis (ISR) with multi-slice computed tomography (MSCT) has not been established yet. We aimed to evaluate the usefulness of measuring coronary lumen density with MSCT to detect ISR. METHODS: Forty-seven coronary stented lesions in 38 patients were evaluated with 16-slice CT (collimation thickness, 0.625 mm). In each assessable lesion, the stent lumen was visually evaluated, and reference CT density proximal to the stent (RCTD) and minimum CT density of the in-stent lumen (SCTD) were measured. ISR was defined as >50% diameter stenosis measured by quantitative coronary angiography (QCA). RESULTS: Of 47 stented lesions, 35 (74%) were assessable, and there were 12 ISR (+) and 23 ISR (-) lesions. Mean DeltaCTD (RCTD-SCTD) of the ISR (+) group was significantly greater than that of the ISR (-) group (196+/-101 vs. 7+/-30 HU, p<0.001). Predictive accuracy of quantitative evaluation of ISR using our best cutoff value of DeltaCTD was higher than that of visual evaluation (97% vs. 83%, p<0.05). The DeltaCTD showed a higher correlation with percent diameter stenosis (r=0.85, p<0.001) than with SCTD (r=-0.73, p<0.001). CONCLUSIONS: Measuring differences of CT densities between reference vessel lumens and in-stent lumens using MSCT is a convenient and useful technique to detect ISR.

Evaluation of hepatocellular carcinoma supplied by the right inferior phrenic artery at initial treatment.

OBJECTIVES: Recurrent hepatocellular carcinoma (HCC) often occurs with extrahepatic supply because of various factors. The right inferior phrenic artery (RIPA) is the most frequent extrahepatic feeding artery, however, it is rarely found that the RIPA supplies the tumor in patients with HCC at initial treatment. The purpose of this study is to evaluate the radiological findings of untreated cases of HCC fed by the RIPA. MATERIALS AND METHODS: Medical records, computed tomography scans, and angiograms in 14 patients with HCC fed by the RIPA at initial therapy were reviewed. We evaluated growth pattern, size, location of tumors, and patency of the hepatic artery. RESULTS: In all cases, tumors showed exophytic growth. Eleven cases (79%) were massive type. Tumor size ranged from 4.5 cm to 16.8 cm (mean, 11.1 cm). In 11 cases (79%), tumors were mainly located in liver segment 7. The patency of the hepatic arteries was intact in all cases. CONCLUSIONS: Regardless of initial therapy, HCC with exophytic growth pattern, especially located in the hepatic areas directly beneath the diaphragm and of massive type, can be supplied by the RIPA.

Comprehensive evaluation of noncalcified coronary plaque characteristics detected using 64-slice computed tomography in patients with proven or suspected coronary artery disease.

BACKGROUND: Multislice computed tomography has recently been shown to have the potential to characterize noncalcified coronary atherosclerotic lesions (NCALs). We evaluated the relationship among computed tomography (CT) density, arterial remodeling, and the adherent calcium morphology of NCALs detected using 64-slice CT. METHODS: We studied 138 patients with proven or suspected coronary artery disease who underwent contrast-enhanced 64-slice CT examination. For each NCAL detected within the vessel wall, we determined the minimum CT density, remodeling index (RI = lesion/reference vessel area), and the presence or absence of coronary calcium in or adjacent to each NCAL and its morphology. Intravascular ultrasound (IVUS) was additionally performed in a subset of 21 patients. RESULTS: A total of 202 NCALs were detected in 97 patients. The mean CT density of 98 lesions with positive remodeling (PR) (RI >1.05) was significantly lower than that of 104 lesions without PR (25 +/- 23 vs 56 +/- 28 Hounsfield units, P < .001); and spotty calcium was more frequently observed with the PR lesions than non-PR lesions (59% vs 22%, P < .001). The mean CT density of the PR lesions with spotty calcium (n = 58) was substantially lower than that of the non-PR lesions without adherent calcium (n = 45) (20 +/- 20 vs 67 +/- 24 Hounsfield units, P < .001). Evaluation of the components, RI, and adherent calcium morphology of 38 NCALs by 64-slice CT was in close agreement with the IVUS findings. CONCLUSIONS: Lower CT density, PR, and adherent spotty calcium, which may indicate plaque vulnerability, are intimately co-related in NCALs detected using 64-slice CT; these findings are consistent with those of IVUS.

Traumatic mesenteric bleeding managed solely with transcatheter embolization.

We report a rare case of mesenteric bleeding following blunt abdominal trauma successfully treated solely with transcatheter arterial embolization (TAE) of the right colic marginal artery. A 56-year-old woman presented with mesenteric bleeding after being involved in a car accident. Computed tomography (CT) showed a large mesenteric hematoma and hemoperitoneum with no associated major injuries to other organs. There was a pseudoaneurysm with extravasation inside the hematoma. TAE was attempted to control bleeding during the preparation for surgical laparotomy. A superior mesenteric angiogram revealed a right colic marginal artery pseudoaneurysm. After successful TAE with microcoils, the affected colon perfusion was preserved via collateral circulation from the ileocolic artery. No ischemic gastrointestinal complications have occurred, and laparotomy has not been necessary during the 6 months after TAE. In isolated mesenteric injury cases, TAE may be a reasonable alternative to emergency laparotomy.

The impact of motion artifacts on the reproducibility of repeated coronary artery calcium measurements.

The purpose of this study is, using a 16-section multidetector-row helical computed tomography (MDCT) scanner with retrospective reconstruction, to compare variability in repeated coronary calcium scoring and qualitative scores of the motion artifacts. One hundred forty-four patients underwent two subsequent scans using MDCT. According to Agatston and volume algorithms, the coronary calcium scores during mid-diastole (the center corresponding to 70% of the R-R cycle) were calculated and the inter-scan variability was obtained. Motion artifacts from coronary artery calcium were subjectively evaluated and classified using a 5-point scale: 1, excellent; no motion artifacts; 2, fine, minor motion artifacts; 3, moderate, mild motion artifacts; 4, bad, severe motion artifacts; 5, poor, doubling or discontinuity. Each reading was done by vessels (left main, left descending, left circumflex and right coronary arteries) and the motion artifact score (mean of the scales) was determined per patient. The variability in the low (1.2+/-0.2) and high (2.4+/-0.6) motion artifact score groups was 7+/-6 (median, 6)% and 19+/-15 (16)% on the Agatston score (P<0.01) and 7+/-7 (6)% and 16+/-13 (14)% on the volume score (P<0.01), respectively. In conclusion, motion has a significant impact on the reproducibility of coronary calcium scoring.

Pseudoaneurysm embolization and vasopressin infusion for lower gastrointestinal bleeding due to recurrence of urinary bladder carcinoma.

We report a case that was successfully treated for massive lower gastrointestinal (LGI) bleeding due to a recurrent urinary bladder carcinoma. Treatment consisted of combination therapy including embolization of an inferior gluteal artery (IGA) pseudoaneurysm and low-dose arterial vasopressin infusion via a sigmoid artery (SA). A 57-year-old man presented with life-threatening sudden, massive LGI bleeding due to an obturator lymph node (LN) metastasis from a urinary bladder carcinoma. Computed tomography showed that the LN recurrence had invaded all the way to the sigmoid colon, and there was a pseudoaneurysm with extravasation inside the recurrence. An angiogram revealed a left IGA pseudoaneurysm. We therefore excluded the pseudoaneurysm by embolization with microcoils. Following this treatment the bleeding decreased, but intermittent LGI bleeding continued. Endoscopic examination showed the tumor with a huge ulcer inside the colonic lumen, and continuous oozing was confirmed. A second angiogram showed no recurrence of the IGA pseudoaneurysm and no apparent findings of bleeding. Then a 3F microcatheter was placed in the SA selectively using a coaxial catheter system, and vasopressin was infused at a rate 0.05 U/min for 12 h. Bleeding completely ceased 2 days later. There were no signs of ischemic gastrointestinal complications. Massive LGI bleeding has not recurred in 5 months.

Gynecologic abscess: CT-guided percutaneous drainage.

A 42-year-old woman with recurrent bilateral endometrial ovarian cystoma presented with fever and pelvic pain caused by a tubo-ovarian abscess (TOA), which was resistant to several varieties of intravenous and oral antibiotics for 2 weeks (Case 1). Computed tomography (CT)-guided diagnostic aspiration for a rapid enlarged right ovarian cystoma through a transabdominal route confirmed that it had developed into a TOA. Subsequent percutaneous abscess drainage (PAD) and irrigation for 3 days were successful. One-year follow-up revealed no recurrence of TOA. A 58-year-old woman with recurrent cervical cancer after external radiation therapy (RT) presented with fever, confusion and tremor caused by pyometra (Case 2). Since transvaginal drainage was impossible due to cervical os obstruction, the patient had undergone CT-guided transabdominal PAD and irrigation for a month. Thereafter, the clinical findings improved and a tracheloplasty was performed to prevent recurrence. CT-guided PAD may be a useful treatment option for gynecologic abscess as a diagnostic aspiration, a temporizing procedure until surgery, or an alternative surgery.

Variability of repeated coronary artery calcium measurements on low-dose ECG-gated 16-MDCT.

OBJECTIVE: High reproducibility on coronary artery calcium (CAC) scoring is a key requirement in monitoring the progression of coronary atherosclerosis. Retrospective ECG-gated helical CT has been shown to be superior to prospective gating helical CT in the reproducibility of CAC measurements. However, it brings with it a high level of radiation exposure. The purpose of this study was to compare low- and standard-dose protocols in the variability of CAC scores and in image quality, thereby assessing the feasibility of low-dose retrospective ECG-gated helical CT in CAC measurements. SUBJECTS AND METHODS: Eighty-six patients with CAC were scanned using a tube current setting of 100 mA once and then a tube current setting equivalent to the patient's body weight twice. CAC scores (Agatston and volume) and interscan variability were evaluated. The mean and SD of the CT attenuation values in regions of interest in the aorta were measured, and the value (mean + 2 x SD) was obtained. RESULTS: A high correlation of log(10) (Agatston score + 1) was observed between sequential helical CT scans (r = 0.998). The variability in CAC measurements ranged from 11% to 12% for both the Agatston and volume scores. With the tube current equivalent to body weight, the value (mean + 2 x SD) did not exceed a CT attenuation value of 130 H. CONCLUSION: Low-dose retrospective ECG-gated helical CT-yielding low variability and achieving the level of image quality needed to measure CAC-can be used to monitor patients with coronary atherosclerosis.

Complications of transfemoral removal of percutaneous transfemorally implanted port-catheter systems.

Our purpose is to evaluate the feasibility and safety of the withdrawal procedure of percutaneous transfemorally implanted port-catheter systems. Thirty-seven patients (17.7%) underwent the withdrawal procedure of this port-catheter system among 209 patients. The reasons for withdrawal were as follows: termination of intra-arterial chemotherapy (n = 7), obstruction of hepatic artery (n = 5), port infection (n = 4), catheter infection (n = 4), catheter obstruction (n = 4), lower-limb palsy and pain (n = 2), exposure of the port due to skin defect (n = 2), patient's desire (n = 2), side effect of chemotherapy (n = 1), no effectiveness of chemotherapy (n = 1), hematoma at the puncture site (n = 1), duodenum perforation by the catheter (n = 1), intermittent claudication due to severe stenosis of right common iliac artery (n = 1), dissection of common hepatic artery (n = 1), and broken catheter (n = 1). In thirty-four of the 37 cases, the port-catheter system was successfully withdrawn without any complications. Clinical success rate was 91.9%. Complications occurred in three cases (8.1%), which were a pseudoaneurysm, thromboembolism of the right common iliac artery, and continuous bleeding from the subcutaneous pocket where the port system was placed for 1 month. In 15 cases, correction of the catheter tip or exchange for dislocation of the tip had to be done without withdrawal. It is not rare to withdraw port-catheter systems in cases of infection or hematoma around the system. Although withdrawal of a percutaneous transfemorally implanted port-catheter system is a relatively safe procedure, the port-catheter system should not be removed unless absolutely indicated.

Multidetector CT angiography using a dual-head power injector and bolus tracking for the diagnosis of aortic aneurysms at reduced contrast material dosage.

RATIONALE AND OBJECTIVES: To establish the utility of multidetector computed tomography (CT) angiography using dual-head power injector in the diagnosis of aortic diseases. METHODS: In a prospective study, 151 patients with aortic diseases were examined by four-detector CT. Scanning was performed using bolus tracking technique. In all patients nonionic contrast was injected at the rate of 1.5 mL/sec. One hundred one patients were examined with dual-head power injector using 0.6 mL/kg contrast flushed by 30 mL of saline solution (group D). Fifty patients were examined with single-head power injector using 1.0 mL/kg contrast only (group S). We evaluated CT values at descending aorta, upper abdominal aorta, abdominal aortic bifurcation, and bilateral common femoral arteries. RESULTS: There were no statistically significant difference of CT values at descending aorta, upper abdominal aorta, abdominal aortic bifurcation, and right common femoral artery. At left common femoral artery, CT values in group D were higher than those in group S with statistically difference (P < .05). In group D, about 40% dose reduction was achieved without reducing image qualities. CONCLUSION: Multidetector CT angiography using dual-head power injector was valuable for the contrast dose reduction of aortic diseases.

Endovascular therapy of pulmonary arteriovenous malformations: Utility of 16-detector-row computed tomography pulmonary angiography as a pre-embolization survey.

The utility of computed tomography pulmonary angiography (CTPA) for coil embolization therapy of pulmonary arteriovenous malformations (PAVMs) was considered. Three consecutive patients (group A) with PAVMs underwent CTPA and coil embolization. The CTPA was performed using a 16-detector-row computed tomography scanner. After careful selection of pulmonary vessel trees, each feeding artery, nidus, and drainage vein was colored using different codes. By using the colored images, a 5-French catheter was shaped to fit to each feeding artery, the best fluoroscopic angle to select each feeding artery was chosen, and interlocking detachable coils (IDCs) were used in embolization. The procedure time and contrast material dose of group A were compared with those of the previous 3 patients (group B) who were treated by the conventional method. All PAVMs of both groups were completely embolized without coil migration. The average procedure time per lesion was 48.4 minutes for group A and 124.0 minutes for group B (P < 0.05). The average contrast material dose per lesion was 37.5 mL in group A and 76.0 mL in group B (P < 0.05). Using CTPA and IDCs, procedure time and contrast material dose were statistically significantly reduced. This combination therapy is useful in treating PAVMs less invasively.

Timing on 16-slice scanner and implications for 64-slice cardiac CT: do you start scanning immediately after breath hold?

RATIONALE AND OBJECTIVES: Slow heart rate and small changes in heart rate are factors for improving image quality on spiral cardiac computed tomography (CT). The purpose of this study is to investigate whether it is possible to improve non-enhanced cardiac CT quality by delaying the data-acquisition window after breath hold. MATERIALS AND METHODS: Electrocardiograph files (n = 240) for 16-slice non-enhanced cardiac CT scans were analyzed. Mean heart rates and maximal changes in heart rates between adjacent cardiac cycles were compared between phase 1 (defined as cardiac cycles 1-5), phase 2 (cardiac cycles 2-6), ... , and phase 6 (cardiac cycles 6-10). RESULTS: Heart rates gradually increased by phases, but were limited to a range of 66.8-68.0 beats/min. Maximal changes in heart rates were 2.5 beats/min (phase 1) at the highest and 1.3 beats/min (phases 5 and 6) at the lowest (t-test; P < .01). Maximal changes in heart rates for more than five beats/min occurred in 24, eight, and eight patients on phases 1, 5, and 6, respectively (chi-square test; P < .01). CONCLUSION: The delayed scan (four or five cardiac cycles after breath hold) has the potential to improve the quality of non-enhanced cardiac CT.

Electron beam CT versus 16-slice spiral CT: how accurately can we measure coronary artery calcium volume?

The purpose of this study was to investigate how accurately CAC volume we can be measured using electron beam computed tomography (CT) and 16-slice spiral CT. CAC models with known volume attached to a cardiac phantom were scanned. The error of measurement, variability between measured and real volumes, and inter-scan measurement variability were obtained. For spiral CT, seven different parameters were included: (1) slice thickness (0.625 mm, 1.25 mm and 2.5 mm), (2) retrospective spiral electrocardiograph (ECG)-gated or prospective axial ECG-triggering, (3) overlapping or non-overlapping. The error of measurement was 15% on electron beam CT and 8-20% on spiral CT. CAC volumes were underestimated in 92% and overestimated in 8% of the electron beam CT scans. Volumes were underestimated in 79%, correct in 5% and overestimated in 16% of the spiral CT scans. The best measurement and the least variability was observed on 0.625-mm retrospective spiral ECG-gated CT (error of 8%), a significant result (t-test: P<0.01) when compared with electron beam CT. CAC volume measurement on CT scanners may be significantly different and often underestimates the real volume of CAC. For precise evaluation of CAC volume, thin-slice retrospective spiral ECG-gated scan using a spiral CT scanner is desirable.

Electron beam CT versus 16-MDCT on the variability of repeated coronary artery calcium measurements in a variable heart rate phantom.

OBJECTIVE: High reproducibility of coronary artery calcium (CAC) scoring is a key requirement for monitoring the progression of coronary atherosclerosis. The purposes of this study were to compare electron beam CT and 16-MDCT scanners in the variability of repeated CAC measurements and to assess the factors influencing this variability. MATERIALS AND METHODS: CAC models of different sizes attached to a cardiac phantom with a programmable variable heart rate were scanned three times, and interscan variability of the CAC measurement was calculated each time. For helical CT, different slice-thickness images of either retrospective ECG-gated or prospective ECG-triggering reconstruction were obtained. The detection of small amounts of calcium, variability of the Agatston score, and CAC measurement algorithms (Agatston, volume, and mass scores) were compared between CT scanners and protocols. RESULTS: All 1-mm-sized calcium models were detected on 0.625- and 1.25-mm helical CT, whereas some were missed on electron beam CT and 2.5-mm helical CT. Retrospective ECG-gated thin-slice helical CT showed the lowest variability. Reduction of variability by volume and mass scoring algorithms was less effective on 0.625- and 1.25-mm-thickness CT. CONCLUSION: Retrospective ECG-gated thin-slice helical CT has the potential to be a useful tool for monitoring coronary atherosclerosis.

Radiofrequency ablation therapy combined with cementoplasty for painful bone metastases: initial experience.

The purpose of this study was to assess the efficacy and safety of percutaneous radiofrequency (RF) ablation therapy combined with cementoplasty under computed tomography and fluoroscopic guidance for painful bone metastases. Seventeen adult patients with 23 painful bone metastases underwent RF ablation therapy combined with cementoplasty during a 2-year period. The mean tumor size was 52 x 40 x 59 mm. Initial pain relief, reduction of analgesics, duration of pain relief, recurrence rate of pain, survival rate, and complications were analyzed. The technical success rate was 100%. Initial pain relief was achieved in 100% of patients (n=17). The mean VAS scores dropped from 63 to 24 (p<0.001) (n=8). Analgesic reduction was achieved in 41% (7 out of 17 patients). The mean duration of pain relief was 7.3 months (median: 6 months). Pain recurred in three patients (17.6%) from 2 weeks to 3 months. Eight patients died and 8 patients are still alive (a patient was lost to follow-up). The one-year survival rate was 40% (observation period: 1--30 months). No major complications occurred, but one patient treated with this combined therapy broke his right femur 2 days later. There was transient local pain in most cases, and a hematoma in the psoas muscle (n=1) and a hematoma at the puncture site (n=1) occurred as minor complications. Percutaneous RF ablation therapy combined with cementoplasty for painful bone metastases is effective and safe, in particular, for bulky tumors extending to extraosseous regions. A comparison with cementoplasty or RF ablation alone and their long-term efficacies is needed.