Comparison of 18F-FDG avidity at PET of benign and malignant pure ground-glass opacities: a paradox? Part II: artificial neural network integration of the PET/CT characteristics of ground-glass opacities to predict their likelihood of malignancy.

AIM: To assess the ability of artificial neural networks (ANNs) to predict the likelihood of malignancy of pure ground-glass opacities (GGOs), using observations from computed tomography (CT) and 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) images and relevant clinical information. MATERIALS AND METHODS: One hundred and twenty-five cases of pure GGOs described in a previous article were used to train and evaluate the performance of an ANN to predict the likelihood of malignancy in each of the GGOs. Eighty-five cases selected randomly were used for training the network and the remaining 40 cases for testing. The ANN was constructed from the image data and basic clinical information. The predictions of the ANN were compared with blinded expert estimates of the likelihood of malignancy. RESULTS: The ANN showed excellent predictive value in estimating the likelihood of malignancy (AUC = 0.98±0.02). Employing the optimal cut-off point from the receiver operating characteristic (ROC) curve, the ANN correctly identified 11/11 malignant lesions (sensitivity 100%) and 27/29 benign lesions (specificity 93.1%). The expert readers found 23 lesions indeterminate and correctly identified 17 lesions as benign. CONCLUSION: ANNs have potential to improve diagnostic certainty in the classification of pure GGOs, based upon their CT appearance, intensity of FDG uptake, and relevant clinical information, and may therefore, be useful to help direct clinical and imaging follow-up.

Comparison of the 18F-FDG avidity at PET of benign and malignant pure ground-glass opacities: a paradox?

AIM: To determine if pure ground-glass opacities (GGOs) and the subgroup of ground-glass nodules (GGNs) typically demonstrate higher 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) uptake at positron-emission tomography (PET) when benign than when malignant. MATERIALS AND METHODS: Informed consent was waived for this institutional review board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA) compliant, retrospective study. A review of all 1,864 combined PET/computed tomography (CT) examinations performed in 2011 on a single system to identify pure GGOs with mean diameter ≥1 cm yielded 166 GGOs. Two blinded subspecialty-trained thoracic radiologists independently assessed GGO size, morphology, attenuation, and location on CT. A blinded nuclear radiologist procured the SUVmax for each GGO. Final diagnosis of malignancy (n=21) was made based on histopathology or upon increased size and attenuation; a final diagnosis of benignity (n=106) was made if GGO resolved, was new within 3 months, evolved in a manner consistent with pulmonary fibrosis, or was stable for ≥60 months; 29 were indeterminate and were excluded, along with 10 cases with unreliable SUVmax measurements, yielding 127 GGOs, of which 68 were GGNs, in 76 patients. RESULTS: The SUVmax was significantly higher in benign than malignant GGOs (p=0.0017) and in the GGN subgroup (p=0.03). A threshold SUVmax >1.5 for GGOs, including GGNs, assured benignity in this cohort. CONCLUSION: Benign GGOs and the benign GGN subgroup demonstrated significantly higher FDG uptake at PET than malignant GGOs/GGNs. Awareness of this finding may prevent misinterpretation of highly 18FDG-avid pure GGOs/GGNs as definitively malignant, which could lead to unnecessary thoracic surgery and its associated risks.

Location-weighted CTP analysis predicts early motor improvement in stroke: a preliminary study.

OBJECTIVE: To develop multivariate models for prediction of early motor deficit improvement in acute stroke patients with focal extremity paresis, using admission clinical and imaging data. METHODS: Eighty consecutive patients with motor deficit due to first-ever unilateral stroke underwent CT perfusion (CTP) within 9 hours of symptom onset. Limb paresis was prospectively assessed using admission and discharge NIH Stroke Scale (NIHSS) scoring. CTP scans were coregistered to the MNI-152 brain space and subsegmented to 146 pairs of cortical/subcortical regions based on preset atlases. Stepwise multivariate binary logistic regressions were performed to determine independent clinical and imaging predictors of paresis improvement. RESULTS: The rates of early motor deficit improvement were 18/49 (37%), 15/42 (36%), 8/25 (32%), and 7/23 (30%) for the right arm, right leg, left arm, and left leg, respectively. Admission NIHSS was the only independent clinical predictor of early limb motor deficit improvement. Relative CTP values of the inferior frontal lobe white matter, lower insular cortex, superior temporal gyrus, retrolenticular portion of internal capsule, postcentral gyrus, precuneus parietal gyri, putamen, and caudate nuclei were also independent predictors of motor improvement of different limbs. The multivariate predictive models of motor function improvement for each limb had 84%-92% accuracy, 79%-100% positive predictive value, 75%-94% negative predictive value, 83%-88% sensitivity, and 80%-100% specificity. CONCLUSIONS: We developed pilot multivariate models to predict early motor functional improvement in acute stroke patients using admission NIHSS and atlas-based location-weighted CTP data. These models serve as a "proof-of-concept" for prospective location-weighted imaging prediction of clinical outcome in acute stroke.

Predicting language improvement in acute stroke patients presenting with aphasia: a multivariate logistic model using location-weighted atlas-based analysis of admission CT perfusion scans.

BACKGROUND AND PURPOSE: Prediction of functional outcome immediately after stroke onset can guide optimal management. Most prognostic grading scales to date, however, have been based on established global metrics such as total NIHSS score, admission infarct volume, or intracranial occlusion on CTA. Our purpose was to construct a more focused, location-weighted multivariate model for the prediction of early aphasia improvement, based not only on traditional clinical and imaging parameters, but also on atlas-based structure/function correlation specific to the clinical deficit, using CT perfusion imaging. MATERIALS AND METHODS: Fifty-eight consecutive patients with aphasia due to first-time ischemic stroke of the left hemisphere were included. Language function was assessed on the basis of the patients admission and discharge NIHSS scores and clinical records. All patients had brain CTP and CTA within 9 hours of symptom onset. For image analysis, all CTPs were automatically co-registered to MNI-152 brain space and parcellated into mirrored cortical and subcortical regions. Multiple logistic regression analysis was used to find independent imaging and clinical predictors of language recovery. RESULTS: By the time of discharge, 21 (36%) patients demonstrated improvement of language. Independent factors predicting improvement in language included rCBF of the angular gyrus GM (BA 39) and the lower third of the insular ribbon, proximal cerebral artery occlusion on admission CTA, and aphasia score on the admission NIHSS examination. Using these 4 variables, we developed a multivariate logistic regression model that could estimate the probability of early improvement in aphasia and predict functional outcome with 91% accuracy. CONCLUSIONS: An imaging-based location-weighted multivariate model was developed to predict early language improvement of patients with aphasia by using admission data collected within 9 hours of stroke onset. This pilot model should be validated in a larger, prospective study; however, the semiautomated atlas-based analysis of brain CTP, along with the statistical approach, could be generalized for prediction of other outcome measures in patients with stroke.

Comparison of squamous cell carcinoma and adenocarcinoma of the lung by metabolomic analysis of tissue-serum pairs.

The prospect of establishing serum metabolomic profiles offers great clinical significance for its potential to detect human lung cancers at clinically asymptomatic stages. Patients with suspicious serum metabolomic profiles may undergo advanced radiological tests that are too expensive to be employed as screening tools for the mass population. As the first step to establishing such profiles, this study investigates correlations between tissue and serum metabolomic profiles for squamous cell carcinoma (SCC) and adenocarcinoma (AC) in the lungs of humans. Tissue and serum paired samples from 14 patients (five SCCs and nine ACs), and seven serum samples from healthy controls were analyzed with high-resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS (1)HMRS). Tissue samples were subjected to quantitative histological pathology analyses after MRS. Based on pathology results, tissue metabolomic profiles for the evaluated cancer types were established using principal component and canonical analyses on measurable metabolites. The parameters used to construct tissue cancer profiles were then tested with serum spectroscopic results for their ability to differentiate between cancer types and identify cancer from controls. In addition, serum spectroscopic results were also analyzed independent of tissue data. Our results strongly indicate the potential of serum MR spectroscopy to achieve the task of differentiating between the tested human lung cancer types and from controls.

Changes in MRS neuronal markers and T cell phenotypes observed during early HIV infection.

OBJECTIVE: To determine if changes in brain metabolites are observed during early HIV infection and correlate these changes with immunologic alterations. METHODS: Eight subjects with early HIV infection, 9 HIV-seronegative controls, and 10 chronically HIV-infected subjects without neurologic impairment underwent 1H magnetic resonance spectroscopy. Subjects with early stage infection were identified near the time of HIV seroconversion and imaged within 60 days of an evolving Western blot, while still having detectable plasma virus. Subjects had blood drawn for viral RNA and T cell quantification. RESULTS: Both N-acetylaspartate (NAA) and Glx (glutamate + glutamine) were decreased in the frontal cortical gray matter of seropositive subjects. NAA levels were found to be decreased in the centrum semiovale white matter of chronically HIV-infected subjects, but not in those with early infection. Both HIV-infected cohorts demonstrated a lower number of CD4+ T lymphocytes and a higher number of CD8+ T lymphocytes in their blood. Lower NAA levels in the frontal cortex of subjects with early infection were associated with an expansion of CD8+ T cells, especially effector CD8+ T cells. CONCLUSIONS: These results verify metabolism changes occurring in the brain early during HIV infection. Lower NAA and Glx levels in the cortical gray matter suggests that HIV causes neuronal dysfunction soon after infection, which correlates to the expansion of CD8+ T cells, specifically to an activated phenotype. Utilizing magnetic resonance spectroscopy to track NAA levels may provide important information on brain metabolic health while allowing better understanding of the virus-host interactions involved in CNS functional deficits.

Intra-arterial nicardipine infusion improves CT perfusion-measured cerebral blood flow in patients with subarachnoid hemorrhage-induced vasospasm.

BACKGROUND AND PURPOSE: Our aim was to determine the effects of intra-arterial (IA) nicardipine infusion on the cerebral hemodynamics of patients with aneurysmal subarachnoid hemorrhage (aSAH)-induced vasospasm by using first-pass quantitative cine CT perfusion (CTP). MATERIALS AND METHODS: Six patients post-aSAH with clinical and transcranial Doppler findings suggestive of vasospasm were evaluated by CT angiography and CTP immediately before angiography for possible vasospasm treatment. CTP was repeated immediately following IA nicardipine infusion. Maps of mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were constructed and analyzed in a blinded manner. Corresponding regions of interest on these maps from the bilateral middle cerebral artery territories and, when appropriate, the bilateral anterior or posterior cerebral artery territories, were selected from the pre- and posttreatment scans. Normalized values were compared by repeated measures analysis of variance. RESULTS: Angiographic vasospasm was confirmed in all patients. In 5 of the 6 patients, both CBF and MTT improved significantly in affected regions in response to nicardipine therapy (mean increase in CBF, 41 +/- 43%; range, -9%-162%, P = .0004; mean decrease in MTT, 26 +/- 24%; range, 0%-70%, P = .0002). In 1 patient, we were unable to quantify improvement in flow parameters due to section-selection differences between the pre- and posttreatment examinations. CONCLUSIONS: IA nicardipine improves CBF and MTT in ischemic regions in patients with aSAH-induced vasospasm. Our data provide a tissue-level complement to the favorable effects of IA nicardipine reported on prior angiographic studies. CTP may provide a surrogate marker for monitoring the success of treatment strategies in patients with aSAH-induced vasospasm.

Role of recanalization in acute stroke outcome: rationale for a CT angiogram-based "benefit of recanalization" model.

BACKGROUND AND PURPOSE: In acute middle cerebral artery (MCA) stroke, CT angiographic (CTA) source images (CTA-SI) identify tissue likely to infarct despite early recanalization. This pilot study evaluated the impact of recanalization status on clinical and radiologic predictors of patient outcomes. MATERIALS AND METHODS: Of 44 patients undergoing CT/CTA within 6 hours of developing symptoms of proximal MCA ischemia, 19 patients achieved complete proximal MCA (MCA M1) recanalization. Admission National Institutes of Health Stroke Scale (NIHSS) score, onset-to-imaging time, CTA-SI Alberta Stroke Program Early CT Score, MCA M1 occlusion, cerebrovascular collaterals score, and CTA-SI lesion volume were correlated with 3- to 6-month follow-up modified Rankin Scale (mRS). We developed 2 stepwise regression models: one for patients with complete MCA M1 recanalization and one for patients without complete recanalization. RESULTS: Complete and incomplete recanalization groups had similar median admission NIHSS scores (19 versus 19) and mean onset-to-imaging times (2.3 versus 1.9 hours) but different proportions of patients achieving mRS scores 0-2 (74% versus 40%; P = .04). The only independent predictors of clinical outcome in patients with complete recanalization were onset-to-imaging time and admission CTA-SI lesion volume (total model R(2) = 0.75; P = .01). The only independent predictors of outcome in patients with incomplete recanalization were admission CTA-SI lesion volume and NIHSS score (total model R(2) = 0.66; P = .007). CONCLUSION: Regardless of recanalization status, admission CTA-SI lesion volume was associated with clinical outcome. Recanalization status did, however, affect which variables in addition to CTA-SI volume significantly impacted clinical outcome: time with complete recanalization and NIHSS with incomplete recanalization. This finding may support the development of a model predicting the potential clinical benefit expected with early successful recanalization.

Renal manifestations of tuberous sclerosis complex: Incidence, prognosis, and predictive factors.

Tuberous sclerosis complex is a genetic disorder characterized by hamartomatous lesions in multiple organs, frequently involving the kidney. We conducted a retrospective review of the clinical and radiographic records of 167 patients with tuberous sclerosis to determine the frequency of renal disease, the likelihood of significant renal morbidity, and the effects of genotype (TSC1 vs TSC2) and gender on renal phenotype. Renal lesions were seen in 57.5% of patients. Of these, angiomyolipoma (AML) occurred in 85.4%, cysts in 44.8%, and renal cell carcinoma in 4.2%. Both AML and cysts were significantly more common and more numerous in TSC2 than in TSC1. AML was significantly more common in female than in male patients, but cysts showed no correlation with gender. Eleven patients developed renal abnormalities during their care in this practice at an average age of onset of 11.3 years (range 3.8-23 years). The frequency and number of renal lesions were positively correlated with age. Interventions, including arterial embolization and nephrectomy, were performed in 11 (6.6%) patients. Among female patients with lymphangioleiomyomatosis, renal AML was universally present. Our findings confirm a high rate of renal involvement; a low rate of serious complications; significant associations between renal involvement, genotype, and gender; and a significant association between renal and pulmonary involvement in female patients.

Improved detection of metastatic melanoma by T2*-weighted imaging.

BACKGROUND AND PURPOSE: The imaging features of metastatic melanomas are distinctive due to the presence of melanin and the propensity for hemorrhage. Both hemorrhage and melanin can produce T1-weighted hyperintensity and T2*-weighted signal intensity loss. We hypothesized that T2*-weighted images would improve detection of metastatic melanoma. METHODS: The T2* and T1 characteristics of 120 newly detected metastatic brain lesions from 31 patients with malignant melanoma were compared with those of 120 brain metastases from 23 patients with lung cancer. RESULTS: Melanoma metastases were 5 times more likely to demonstrate prominent T2*-related signal intensity loss (susceptibility effect) than were lung metastases (42% vs 8%; P < .01), and 4.5 times more likely to demonstrate T1 hyperintensity (55% vs 12%; P < .01). Patients with melanoma had lesions that were either hypointense on T2*-weighted images, hyperintense on T1 images, or both, in 71% (85/120), compared with 19% (23/120) of lung carcinoma metastases (P < .01). Melanoma lesions were 16 times more likely than lung cancer lesions to show combined T2* related signal intensity loss and T1 hyperintensity (P < .01). Remarkably, 8 melanoma lesions (7%) in 3 patients were detectable principally on the T2*-weighted sequences, whereas no lung cancer lesion was detected solely on susceptibility images. We found a direct correlation between melanin content and T1 hyperintensity but no correlation between T2* intensity and melanin. CONCLUSION: T2*-weighted images improve lesion detection in patients with melanoma metastases, and in conjunction with T1-weighted sequences, can suggest melanoma as the etiology of an intracranial mass. This sequence should be employed for evaluation of possible brain metastasis in patients without a known primary malignancy and in studies for melanoma staging.

Diagnostic evaluation of patients with a brain mass as the presenting manifestation of cancer.

BACKGROUND: Patients with a newly detected brain mass and no history of cancer often undergo extensive diagnostic testing in search of a systemic primary neoplasm prior to selection of a biopsy site, potentially leading to unnecessary expense and delay. We sought patterns in the evaluation of these patients to allow rapid selection of a biopsy site. METHODS: We compared the diagnostic evaluation of 176 patients with newly detected brain masses who were ultimately determined to have a metastatic or primary lesion. RESULTS: In 88 patients presenting with brain metastasis, lung cancer was markedly overrepresented as a primary tumor, occurring in 82% of patients. Brain MRI and chest CT together identified the site for diagnostic biopsy in all except for two of the 176 patients. One-half of the patients with metastasis had brain biopsy as the primary diagnostic procedure, with 80% undergoing a craniotomy rather than needle biopsy. The initial management decision in the majority of metastasis patients was whether to perform a craniotomy for resection of tumor. Whereas patients with single and cerebellar lesions were most likely to undergo craniotomy, the extent of systemic disease did not affect the decision to recommend a neurosurgical procedure. The average time to biopsy for patients with metastatic and primary tumors was 4.7 days and 6.0 days. In this retrospective population, we estimated that evaluation with brain MRI and chest CT, followed by an early neurosurgical decision, could reduce the time to diagnosis by at least 10%. CONCLUSIONS: Chest CT and brain MRI, if used together as initial diagnostic studies, would have identified a biopsy site in 97% of patients with a newly detected brain mass.

Tumour size measurement in an oncology clinical trial: comparison between off-site and on-site measurements.

AIM: To evaluate the degree of variability between lesion measurements obtained by a single observer compared with multiple observers, and in selected cases evaluate which of the two measurements more accurately represented the lesion size. MATERIALS AND METHODS: In this study we compared the performance of a single off-site observer to multiple on-site observers during measurement of 300 abdominal and thoracic lesions. Lesion measurements that were larger than 1cm(2), differed by more than 50%, but by less than 100%, were compared by a single adjudicator, who was blinded to the measurement source (n=46). RESULTS: Measurements of the 300 lesions differed by an average of 109% (SD 251%). Of 266 lesions larger than 1cm(2), results of the single observer compared with multiple observers differed by more than 10% for 249 lesions, more than 30% for 169 lesions, more than 50% for 126 lesions, and more than 100% for 66 lesions. Forty-six lesions were compared by the adjudicator. The adjudicator selected the measurement of the single observer for 37 lesions (80.4%), and the measurement determined by one of the multiple observers for nine lesions (19.6%; p=0.00002). CONCLUSION: Measurement of lesion size by a single observer compared with multiple observers reveals a high degree of variability. An adjudicator selected the measurement of the single observer more frequently than that of multiple observers, with statistical significance. These findings suggest that studies designed to quantify imaging features should limit the number of observers.

Evaluation of intracoronary stenting by intravascular optical coherence tomography.

BACKGROUND: Conventional contrast cineangiography and intravascular ultrasound (IVUS) provide a limited definition of vessel microstructure and are unable to evaluate dissection, tissue prolapse, and stent apposition on a size scale less than 100 micro m. OBJECTIVE: To evaluate the use of intravascular optical coherence tomography (OCT) to assess the coronary arteries in patients undergoing coronary stenting. METHODS: OCT was employed in patients having percutaneous coronary interventions. Images were obtained before initial balloon dilatation and following stent deployment, and were evaluated for vessel dissection, tissue prolapse, stent apposition, and stent asymmetry. IVUS images were obtained before OCT, using an automatic pull back device. RESULTS: 42 stents were imaged in 39 patients without complications. Dissection, prolapse, and incomplete stent apposition were observed more often with OCT than with IVUS. Vessel dissection was identified in eight stents by OCT and two by IVUS. Tissue prolapse was identified in 29 stents by OCT and 12 by IVUS; the extent of the prolapse (mean (SD)) was 242 (156) microm by OCT and 400 (100) microm by IVUS. Incomplete stent apposition was observed in seven stents by OCT and three by IVUS. Irregular strut separation was identified in 18 stents by both OCT and IVUS. CONCLUSIONS: Intracoronary OCT for monitoring stent deployment is feasible and provides superior contrast and resolution of arterial pathology than IVUS.

Frequency and clinical context of decreased apparent diffusion coefficient reversal in the human brain.

PURPOSE: To determine the probability that regions of decreased apparent diffusion coefficient (ADC) return to normal without persistent symptoms or T2 change and the settings in which these ADC reversals occur. MATERIALS AND METHODS: Three hundred magnetic resonance (MR) imaging studies were selected at random from a database of 7,147 examinations to determine the probability of a pathologically decreased ADC. In cases with decreased ADC, the clinical history was recorded and, if available, follow-up MR imaging findings were evaluated. Five cases of ADC reversal became known during the same period and were evaluated to determine the initial ADC decrease, clinical outcome, and findings at follow-up imaging. RESULTS: Findings in 116 of 300 MR imaging studies revealed regions of decreased ADC. In 49 of 116 studies, follow-up MR imaging examinations were performed at least 4 weeks after the onset of symptoms; ADC did not reverse. Five cases of ADC reversal were identified in the same period, giving an estimated 0.2%-0.4% probability of ADC reversal. Clinical settings were venous sinus thrombosis and seizure (n = 3), hemiplegic migraine (n = 1), and hyperacute arterial infarction (n = 1). Both white matter (n = 3) and gray matter (n = 3) regions were involved. CONCLUSION: Reversal of ADC lesions is rare, occurs in complicated clinical settings, and can involve white or gray matter.

Pancreatic cancer: cost-effectiveness of imaging technologies for assessing resectability.

PURPOSE: To evaluate the cost-effectiveness of imaging strategies for the assessment of resectability in patients with pancreatic cancer. MATERIALS AND METHODS: A decision model was developed to calculate costs and benefits (survival) accruing to hypothetical cohorts of patients with known or suspected pancreatic cancer. Results are presented as cost per life-year gained under various scenarios and assumptions of diagnostic test characteristics, surgical mortality, disease characteristics, and costs. RESULTS: With best estimates for all data inputs, the strategy of computed tomography (CT) followed by laparoscopy and laparoscopic ultrasonography (US) had an incremental cost-effectiveness ratio of $87,502 per life-year gained, compared with best supportive care. This strategy was significantly more cost-effective than CT followed by magnetic resonance (MR) imaging and was significantly less expensive than other imaging strategies while providing a statistically and clinically insignificant difference in life-year gains. A strategy involving no imaging (immediate surgery) was more expensive but less effective than all imaging strategies. A hypothetical perfect test with cost equal to that of CT followed by MR had an incremental cost-effectiveness ratio of $64,401 per life-year gained, compared to best supportive care. CONCLUSION: Most available imaging tests for assessing resectability of pancreatic cancer do not differ in effectiveness, but a strategy of CT, laparoscopy, and laparoscopic US would consistently result in significantly lower costs than other imaging tests under a wide range of scenarios.

Percutaneous radio-frequency ablation of hepatic metastases from colorectal cancer: long-term results in 117 patients.

PURPOSE: To describe the results of an ongoing radio-frequency (RF) ablation study in patients with hepatic metastases from colorectal carcinoma. MATERIALS AND METHODS: In 117 patients, 179 metachronous colorectal carcinoma hepatic metastases (0.9-9.6 cm in diameter) were treated with RF ablation by using 17-gauge internally cooled electrodes. Computed tomographic follow-up was performed every 4-6 months. Recurrent tumors were retreated when feasible. Time to new metastases and death for each patient and time to local recurrence for individual lesions were modeled with Kaplan-Meier analysis. Modeling determined the effect of number of metastases on the time to new metastases and death and effect of tumor size on local recurrence. RESULTS: Estimated median survival was 36 months (95% CI; 28, 52 months). Estimated 1, 2, and 3-year survival rates were 93%, 69%, and 46%, respectively. Survival was not significantly related to number of metastases treated. In 77 (66%) of 117 patients, new metastases were observed at follow-up. Estimated median time until new metastases was 12 months (95% CI; 10, 18 months). Percentages of patients with no new metastases after initial treatment at 1 and 2 years were 49% and 35%, respectively. Time to new metastases was not significantly related to number of metastases. Seventy (39%) of 179 lesions developed local recurrence after treatment. Of these, 54 were observed by 6 months and 67 by 1 year. No local recurrence was observed after 18 months. Frequency and time to local recurrence were related to lesion size (P < or =.001). CONCLUSION: RF ablation is an effective method to treat hepatic metastases from colorectal carcinoma.

Effect of multislice CT technology on scanner productivity.

OBJECTIVE: In this study we analyzed the impact of multislice CT technology on scanner productivity in a tertiary care medical center. MATERIALS AND METHODS: We compared the productivity of two diagnostic CT scanners during the periods January 1 to August 31, 1999 (when both scanners had single-slice CT capability) and January 1 to August 31, 2000 (when one of these scanners was replaced with a multislice CT scanner). The scanners were used primarily for outpatients during the day shift and for inpatients during the evening shift; the demand for CT services was stable. For this analysis, we queried the hospital's radiology information system and identified the number of CT examinations performed during the two analysis periods. We also determined the examination mix, including proportion of enhanced and unenhanced examinations and the anatomic region examined, to ensure comparable patient populations. Statistical analysis was performed. RESULTS: The number of CT studies performed on the two scanners increased by 1772 (13.1%) from 13,548 (before multislice CT) to 15,320 (when multislice CT was available). The number of examinations enhanced with contrast media increased from 52% to 65%. Between 9:00 A.M. and 5:00 P.M., the number of CT examinations was similar on the single-slice scanners in the two periods (p > 0.05). However, in the period when multislice CT was available, the number of studies performed on the multislice scanner (5919) was 51.9% higher than those performed using the single-slice scanner (3896) (p < 0.0006). CONCLUSION: Using a multislice CT scanner leads to an increase in CT productivity, even though multislice studies are performed using more complicated protocols than are used on a single-slice CT scanner.

Endovascular versus open surgical elective repair of infrarenal abdominal aortic aneurysm: predictors of patient discharge destination.

PURPOSE: To evaluate patient discharge destination after elective endovascular or open surgical repair of infrarenal abdominal aortic aneurysm and to determine predictors for discharge to home or to a rehabilitation center. MATERIALS AND METHODS: All patients electively treated for infrarenal abdominal aortic aneurysm with endovascular repair (n = 182) or open surgery (n = 274) between January 1997 and September 1999 were included. From the hospital database, information on discharge destination, patient characteristics, complications, and length of stay was retrieved. Multiple logistic regression analysis was performed to determine predictors for discharge to home or to a rehabilitation center. RESULTS: Patient characteristics did not differ significantly between the treatment groups, with the exception of age (mean age, 75.1 vs 72.9 years in the endovascular and open surgical group, respectively; P =.005). Patient discharge destinations differed significantly between the treatment groups (P =.001). After endovascular procedures, 156 (85.7%) of 182 patients went home and 19 (10.4%) of 182 patients went to a rehabilitation center. After open surgery, 187 (68.2%) of 274 patients went home and 64 (23.4%) of 274 patients went to a rehabilitation center. The odds ratio of discharge to a rehabilitation center, instead of home, following endovascular procedures versus open surgery was 0.23 (95% CI: 0.13, 0.43). CONCLUSION: Following elective repair of infrarenal abdominal aortic aneurysm, significantly more patients went home after an endovascular procedure than after open surgery. Procedure type was a significant predictor of discharge destination.

Hospital costs for elective endovascular and surgical repairs of infrarenal abdominal aortic aneurysms.

PURPOSE: To determine and compare the average in-hospital costs of elective open surgical and endovascular repairs of infrarenal abdominal aortic aneurysms. MATERIALS AND METHODS: Total actual cost data for patients undergoing elective endovascular (n = 181) or open surgical (n = 273) repair of abdominal aortic aneurysms between 1997 and 1999 were retrieved. The mean total hospital cost (including stent-graft costs and excluding attending physician fees) and mean postoperative length of stay were calculated for each treatment group. Costs were expressed in 1999 U.S. dollars. RESULTS: Endovascular repair yielded a shorter postoperative length of stay than did open surgery (mean stay, 3.4 vs 8.0 days; P <.001) and a lower proportion of patients who were admitted to the intensive care unit for 1 full day or longer (2.8% vs 36.3%; P <.001). The mean total hospital cost was significantly higher for endovascular repair than for open surgery ($20,716 vs $18,484; P <.001). CONCLUSION: Hospital costs were higher for endovascular repair than for open surgical repair. However, endovascular repair was associated with a decreased length of stay and fewer intensive care unit admissions. The increased mean hospital cost for endovascular repair was smaller than one would expect, considering the higher costs of endovascular grafts, as compared with those for surgical grafts (approximately $6,400 according to literature data).

Inpatient costs of routine endovascular repair of abdominal aortic aneurysm.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the inpatient cost of routine (ie, without emergent conversion to open repair during the hospital stay) endovascular stent-graft placement in a consecutive series of patients undergoing elective endovascular repair of abdominal aortic aneurysm (AAA) at a single institution. MATERIALS AND METHODS: Inpatient hospital costs of 91 patients who underwent initial elective endovascular repair of AAA were analyzed retrospectively. All patients had participated in clinical trials at the authors' institution during the previous 6 years. Financial data were derived from the hospital's cost-accounting system; additional procedural data were collected from a departmental database and with chart review. Stent-graft and professional costs were excluded. RESULTS: The mean total cost for endovascular repair was $11,842 (standard deviation [SD], $5,127), mean procedure time was 149 minutes (SD, 79 minutes), and mean length of stay was 3.5 days (SD, 2.3 days). Total cost depended on stent-graft type (means, $12,428 [bifurcated] vs $9,622 [tube]; P = .0002) and strongly correlated with procedure time and length of hospital stay (r = 0.78 and 0.66, respectively; P < .0001). Ninety-six percent of total costs for all patients were attributable to the following departments: operating theater (31%), radiology (31%), nursing (22%), and anesthesia (12%). CONCLUSION: Overall costs are greater with bifurcated than with tube stent-grafts. Total procedure-related costs are divided relatively equally between the operating theater, the radiology department, and the combination of the nursing and anesthesia departments.