Biomedical subjects

Thomas K Pilgram

Publications and source records attributed to Thomas K Pilgram.

At least 19 recordsLinked to original sources

PubMed2007

Comparison of standard- and low-radiation-dose CT for quantification of emphysema.

OBJECTIVE: This study was performed to compare standard- and low-radiation-dose techniques in the CT quantification of emphysema. MATERIALS AND METHODS: The study population consisted of 36 men and 20 women who were current or former heavy smokers and underwent standard-dose (effective tube current, 100-250 mAs) chest CT at our institution within 6 months of having undergone low-dose (effective tube current, 30-60 mAs) chest CT. All CT scans were reconstructed at 5-mm slice thickness with a smooth filter. CT-measured lung volume, mean and median lung attenuation, and percentage of lung volume with attenuation lower than multiple thresholds (emphysema index values) were compared by Pearson correlation, two-tailed and paired Student's t tests, and regression analysis. RESULTS: There were no significant differences in mean attenuation (-848 vs -846 H, p > 0.35) for the low dose and the standard dose or in median lung attenuation (-879 vs -878 H, p > 0.66). Low- and standard-dose emphysema indexes were correlated at all attenuation thresholds (r = 0.86-0.97). Mean emphysema indexes were higher on the low-dose scans, but the mean difference at all thresholds was less than 3%. The differences were significant (p < 0.05) only at the lower index thresholds, correlated with differences in lung volume (r < or = 0.86), and increased with greater differences in dose. CONCLUSION: Low-dose technique has minimal effect on CT quantification of emphysema.

Aged↗

PubMed2006

Effect of intraarterial papaverine and/or angioplasty on the cerebral veins in patients with vasospasm after subarachnoid hemorrhage due to ruptured intracranial aneurysms.

OBJECT: The goal in this study was to determine if there was a change in intracranial venous diameters after endovascular treatment of carotid distribution vasospasm caused by subarachnoid hemorrhage. METHODS: The venous diameters were measured in all patients who received intraarterial papaverine and/or balloon angioplasty for treatment of vasospasm during the study period of 3 years. To evaluate the veins of Labbe and Trolard, the straight sinus, and the superior sagittal sinus (SSS), measurements were performed in a blinded manner with the aid of a magnification loupe. Predetermined sites were evaluated on angiograms obtained before and after endovascular treatment. Forty-three treatments in 26 patients were included: 18 patients (33 territories) were treated with intraarterial papaverine alone, four (four territories) were treated with balloon angioplasty alone, and four (six territories) were treated with both papaverine infusion and angioplasty. The mean measured venous diameters increased significantly after addition of papaverine (10.9%), and also after combined papaverine and angioplasty (4.2%). There was no statistically significant increase in the mean venous diameters after angioplasty alone. If the initial intracranial pressure (ICP) was less than 15 mm Hg before treatment, the veins showed a greater tendency to dilate than if the initial ICP measurements were greater than 15 mm Hg. The straight sinus and the SSS increased more in diameter than the veins of Labbe and Trolard. There was no statistically significant correlation between the change in venous diameters with treatment and ICP. CONCLUSIONS: Endovascular treatment produces measurable increases in intracranial venous diameters. However, these changes do not correlate with changes in ICP.

Adult↗

PubMed2006

Numerical simulation of the plantar pressure distribution in the diabetic foot during the push-off stance.

The primary objective of conservative care for the diabetic foot is to protect the foot from excessive pressures. Pressure reduction and redistribution may be achieved by designing and fabricating orthotic devices based on foot structure, tissue mechanics, and external loads on the diabetic foot. The purpose of this paper is to describe the process used for the development of patient-specific mathematical models of the second and third rays of the foot, their solution by the finite element method, and their sensitivity to model parameters and assumptions. We hypothesized that the least complex model to capture the pressure distribution in the region of the metatarsal heads would include the bony structure segmented as toe, metatarsal and support, with cartilage between the bones, plantar fascia and soft tissue. To check the hypothesis, several models were constructed with different levels of details. The process of numerical simulation is comprised of three constituent parts: model definition, numerical solution and prediction. In this paper the main considerations relating model selection and computation of approximate solutions by the finite element method are considered. The fit of forefoot plantar pressures estimated using the FEA models and those explicitly tested were good as evidenced by high Pearson correlations (r=0.70-0.98) and small bias and dispersion. We concluded that incorporating bone support, metatarsal and toes with linear material properties, tendon and fascia with linear material properties, soft tissue with nonlinear material properties, is sufficient for the determination of the pressure distribution in the metatarsal head region in the push-off position, both barefoot and with shoe and total contact insert. Patient-specific examples are presented.

Biomechanical Phenomena↗

PubMed2006

Comparison of adjunctive use of rofecoxib versus ibuprofen in the management of postoperative pain after uterine artery embolization.

PURPOSE: The primary purpose of the present study was to compare the antiinflammatory effectiveness of rofecoxib with that of ibuprofen in the first 5 days after uterine artery embolization (UAE). The secondary aim was to compare pain levels and narcotic use among patients treated with different embolic agents. MATERIALS AND METHODS: From July 2003 to June 2004, 68 UAE procedures were performed by one of the authors (D.M.H.). Of this group, 50 women agreed to participate in this study. Exclusion criteria were limited to contraindication to either drug or current steroid or nonsteroidal antiinflammatory drug use. In a randomized, double-blinded fashion, patients received a numbered pill box that contained one of the two agents and its placebo counterpart. Four times per day for 5 days, patients recorded their level of pain on a visual analog scale and the amount of narcotic analgesic drug needed at that time. Score sheets were returned by mail after completion. During the course of the study, three embolic agents (Gold Embospheres, Contour SE particles, and Embospheres) were used in succession, with similar numbers of patients in each group. RESULTS: Four patients were excluded from analysis: two who were readmitted to the hospital for treatment of pain (one treated with each antiinflammatory medication) and two who failed to complete their score sheets. Subject demographics were very similar with respect to antiinflammatory drug treatment and embolic agent, except that the average age of patients in the Embosphere group was 6 years older than in the Embosphere Gold and Contour SE groups (P= .02). There was no difference in the pain level and narcotic drug intake between the two drug arms, but among embolic agents, the Embosphere Gold group tended to have a higher overall average pain score (P = .12), and the two patients readmitted were in this group. Patients in the Contour SE group tended to use a lower amount of narcotic drug than those in the other two embolic agent groups (P = .09). CONCLUSIONS: There was no difference between rofecoxib and ibuprofen with respect to postprocedural pain or narcotic use after UAE. Embolic agent appeared to have a greater impact, with patients in the Embosphere Gold group reporting higher pain scores and those in the Contour SE group requiring a lower amount of narcotic drug than those in the Embosphere Gold or Embosphere groups.

Adult↗

PubMed2006

Angioplasty balloon inflation pressures during treatment of hemodialysis graft-related stenoses.

PURPOSE: This two-part prospective investigation was designed to determine the balloon inflation pressures required to dilate stenoses associated with hemodialysis grafts and evaluate the burst pressures of five different angioplasty balloons. MATERIALS AND METHODS: Eighty-nine patients with dysfunctional hemodialysis grafts were enrolled and underwent fistulography. The diagnostic studies revealed 104 stenoses, which were treated with balloon angioplasty. The characteristics of these stenoses and the balloon inflation pressures required to dilate the lesions were recorded. In part two of this investigation, the burst pressures of five different angioplasty balloons were evaluated immediately after their use during angioplasty procedures. Twenty-five balloons of each type were inflated until the balloon burst or 30 atm of pressure was achieved. Several different statistical tests were used to analyze the data set. RESULTS: The mean balloon inflation pressure required to dilate all 104 stenoses was 17.2 atm. Subgroup analysis revealed that the mean balloon inflation pressure required to dilate 75 venous anastomotic stenoses was 17.9 atm and that a mean pressure of 15.6 atm was required to dilate 29 stenoses located within the native outflow veins. The angioplasty balloon burst pressure experiments revealed that the majority of the tested balloons can be inflated to pressures 5-6 atm greater than the manufacturers' rated burst pressures. However, the margin of safety for overinflation was variable among the balloons tested, and angioplasty balloons experience fatigue with repeated inflations. CONCLUSION: The majority of stenoses associated with hemodialysis grafts can be successfully dilated with use of available high-pressure angioplasty balloons.

Adult↗

PubMed2006

A prospective comparison of the impact of uterine artery embolization, myomectomy, and hysterectomy on ovarian function.

PURPOSE: To prospectively compare uterine artery embolization (UAE) versus myomectomy and hysterectomy with regard to ovarian function as measured by postprocedure follicle-stimulating hormone (FSH) levels and symptoms. MATERIALS AND METHODS: Fifty-five patients were prospectively enrolled in the study: 33 patients who underwent UAE, seven who underwent myomectomy, and 15 who underwent hysterectomy. Patients had serum FSH and estradiol levels measured on the third day of the menstrual cycle before their procedure and at regular follow-up visits for as long as 6 months. At these intervals, patients were also surveyed regarding menopausal symptoms. RESULTS: Although a mild transient increase in mean FSH level after UAE was noted at 3 months, there were no statistically significant differences among the three groups in mean FSH levels at 1 month, 3 months, or 6 months of follow-up. Menopausal symptoms arose in the UAE and hysterectomy groups, but there was no statistically significant difference or permanent effect in either group. CONCLUSION: There is no significant difference in impact on ovarian function after UAE, hysterectomy, or myomectomy at follow-up for a maximum of 6 months.

Adolescent↗

PubMed2006

Osteoporotic compression fractures: outcomes after single- versus multiple-level percutaneous vertebroplasty.

PURPOSE: To compare single- and multiple-level percutaneous vertebroplasty (PV) in terms of pain relief, activity level, and analgesic use in patients with osteoporotic vertebral compression fractures (VCFs). MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained, and the study was HIPAA compliant. One hundred seventy-three patients (mean age at treatment, 73.8 years +/- 11.9 [standard deviation]) with 422 symptomatic osteoporotic VCFs underwent 204 treatment sessions for over 4 years. Pain immediately before and after PV was measured by using a visual analogue scale (VAS). Pain degree, activity level, and analgesic use were assessed at 2 weeks and 1, 3, 6, 12, and 24 months after PV by using telephone interview questionnaires. Data were analyzed by using a combination of paired t tests, analysis of variance, contingency tables, and chi2 tests. RESULTS: Findings of 172 PV treatment sessions for 149 patients (mean age at treatment, 73.4 years +/- 12), 110 (74%) of whom were women, were assessed; 32 treatment cases were lost to follow-up or lost owing to death. A single fracture level was treated at 65 sessions; two fracture levels, at 52 sessions; and three or more fracture levels, at 55 sessions. The mean VAS pain score decreased significantly (P < .001), from 76 +/- 21 before to 19 +/- 27 immediately after PV. Of the outcomes reported at 24 months, 82% (64 of 78 treatment sessions) were marked to complete resolution of the initial pain, 51% were complete cessation of analgesic use, and 51% were increased activity levels. These results did not differ greatly over time or when stratified into groups according to the number of fracture levels treated. CONCLUSION: PV performed at a single fracture level and that performed at multiple fracture levels were equally effective in facilitating long-term pain relief, increased activity level, and decreased analgesic use in patients with osteoporotic VCFs.

Aged↗

PubMed2006

Response of nonmidline pain to percutaneous vertebroplasty.

OBJECTIVE: The purpose of this study was to determine the prevalence of nonmidline symptoms in patients undergoing percutaneous vertebroplasty and the response of these symptoms to vertebroplasty. MATERIALS AND METHODS: This is a retrospective study performed through examination of patient records, baseline questionnaires, demographic sheets, follow-up questionnaires, reports from telephone follow-up, and pain location diagrams completed before and after percutaneous vertebroplasty. Data were gathered from 350 patient encounters, 686 vertebroplasty procedures, and 288 patients. After determining the prevalence of nonmidline pain, analysis of acquired data was performed to determine the efficacy of vertebroplasty in relieving nonmidline pain. RESULTS: Nonmidline pain was present in 240 of 350 patient encounters. Major symptom areas were the ribs; hip, groin, and buttocks; and legs and thighs. Lesser areas of nonmidline symptoms were the abdomen, shoulders, and waistline. Overall there was improvement in nonmidline pain in 83% of the procedures. CONCLUSION: Most patients presenting for percutaneous vertebroplasty have nonmidline pain. Vertebroplasty reduced or eliminated nonmidline pain in 76-92% of the patients in whom it was reported. Procedures involving lumbar vertebrae tended to be successful less often than others, but even in these patients the procedure was successful in approximately 75%.

Adult↗

PubMed2006

Efficacy and mechanism of orthotic devices to unload metatarsal heads in people with diabetes and a history of plantar ulcers.

BACKGROUND AND PURPOSE: Total-contact inserts (TCIs) and metatarsal pads (MPs) frequently are prescribed to reduce excessive plantar stresses to help prevent skin breakdown in people with diabetes mellitus (DM) and peripheral neuropathy. The first purpose of this study was to determine the effect of a TCI and an MP on metatarsal head peak plantar pressures (PPP) and pressure-time integrals (PTI). The second purpose of this study was to determine a possible mechanism of pressure reduction by measuring contact area and loaded soft-tissue thickness (STT) under the metatarsal heads and second metatarsal shaft. SUBJECTS: Twenty subjects (12 men and 8 women; age [mean+/-SD]=57+/-9 years) with DM (duration [mean+/-SD]=16+/-11 years), peripheral neuropathy, and a history of plantar ulcers participated. METHODS: A repeated-measures research design was used, and outcome measures are reported for 3 footwear conditions: shoe, shoe with TCI, and shoe with TCI and MP. In-shoe plantar pressures were collected during walking and during spiral x-ray computed tomography (SXCT). The STT and identification of the pressure sensor and location of the MP in relationship to the metatarsal heads were determined by use of SXCT. RESULTS: The PPP and the PTI were 16% to 24% lower at the metatarsal heads in the TCI condition than in the shoe condition. The PPP and the PTI decreased an additional 15% to 28% (for a total reduction of 29% to 47%) with the addition of the MP. The contact area increased 27% with the TCI but not with the MP. The STT did not increase under the metatarsal heads in the TCI condition (compared with the shoe condition) but did increase 8% to 22% at metatarsal heads 2 to 5 with the addition of the MP. The PPP increased substantially (308%) and the STT decreased 14% under the shaft of the second metatarsal with the addition of the MP to the TCI-plus-shoe condition. DISCUSSION AND CONCLUSION: The TCI and the MP caused substantial and additive reductions of pressures under the metatarsal heads. The TCI reduces excessive pressures at the metatarsal heads by increasing the contact area of weight-bearing forces. Conversely, the MP acts by compressing the soft tissues proximal to the metatarsal heads and relieving compression at the metatarsal heads. These findings can assist in the design of effective orthotic devices to relieve excessive plantar stresses that contribute to skin breakdown and subsequent amputation in people with DM and peripheral neuropathy.

Biomechanical Phenomena↗

PubMed2005

Coronary artery calcification and risk factors for atherosclerosis in patients with venous thromboembolism.

BACKGROUND: Venous thromboembolism (VTE) and atherosclerosis may be associated and may share common risk factors. We conducted a retrospective case-control study to investigate the association between VTE and coronary atherosclerotic disease (CAD) by means of measuring coronary artery calcification and evaluating clinical risk factors. METHODS: From 385 consecutive patients suspected of VTE, we randomly selected 89 cases with idiopathic VTE and 89 controls without VTE, frequency matched on gender and age. Risk factors for atherosclerosis were noted for both groups. Coronary artery calcification was quantified on pulmonary computed tomography (CT) angiographic images. The coronary artery calcification and risk factors were compared between the case and control groups. The associations between VTE and the presence of coronary artery calcium and risk factors were assessed with logistic regression analysis. RESULTS: A higher prevalence of coronary artery calcium was found in the case group (51.7%) than in the control group (28.1%) (p=0.001). The presence of coronary artery calcium was significantly associated with VTE with an odds ratio of 4.3 (95% confidence interval, 1.9-10.1) in a multivariable model. Diabetes mellitus and hypertension were also significantly associated with VTE. CONCLUSION: A significant association between VTE and CAD suggests that CAD is an independent risk factor for VTE. Diabetes and hypertension are also independent risk factors for VTE.

Adult↗

PubMed2005

Quantitative assessment of coronary artery plaque vulnerability by high-resolution magnetic resonance imaging and computational biomechanics: a pilot study ex vivo.

The risk of atherosclerotic plaque disruption is thought to be closely related to plaque composition and rupture triggers such as external mechanical forces. The purpose of this study was to integrate MR imaging and computational techniques for the quantification of plaque vulnerability with morphologic data and biomechanical stress/strain distributions that were all based on high-resolution MR images of coronary artery plaque specimens ex vivo. Twenty-two coronary artery plaque specimens were selectively collected from 10 cadavers. Multislice T(2)-weighted spin echo images were acquired with a resolution of 100 x 100 microm(2). Histopathological images were used as the gold standard for the identification of plaque components and vulnerability. Plaque components were classified on MR images, and the stress/strain components were calculated with a two-dimensional computational model with fluid-structure interactions. As expected, vulnerable plaques appeared to result from a large lipid pool, a thin fibrous cap, and some critical stress/strain conditions. An empiric vulnerability marker was derived and was closely related to the vulnerability score that was determined through pathologic examination. Noninvasive quantification of the MR contrast and mechanical properties of plaque may provide a comprehensive biomarker for the assessment of vulnerability of atherosclerotic plaques.

Biomechanical Phenomena↗

PubMed2005

Feasibility of combining MR perfusion, angiography, and 3He ventilation imaging for evaluation of lung function in a porcine model.

RATIONALE AND OBJECTIVE: To assess the feasibility of combining magnetic resonance (MR) perfusion, angiography, and 3He ventilation imaging for the evaluation of lung function in a porcine model. MATERIALS AND METHODS: Fourteen consecutive porcine models with externally delivered pulmonary emboli and/or airway occlusions were examined with MR perfusion, angiography, and 3He ventilation imaging. Ultrafast gradient-echo sequences were used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast-agent injections. 2D multiple-section 3He imaging was performed subsequently via the inhalation of hyperpolarized 3He gas. The diagnostic accuracy of MR angiography for detecting pulmonary emboli was determined by two reviewers. The diagnostic confidence for different combinations of MR techniques was rated on the basis of a 5-point grading scale (5 = definite). RESULTS: The sensitivity, specificity, and accuracy of MR angiography for detecting pulmonary emboli were approximately 85.7%, 90.5%, and 88.1%, respectively. The interobserver agreement was very strong (k = 0.82). There was a clear tendency for confidence to increase when first perfusion and then ventilation imaging were added to the angiographic image (Wilcoxon signed ranks test, P = 0.03). CONCLUSION: The combination of the three methods of MR perfusion, angiography, and 3H ventilation imaging may provide complementary information on abnormal lung anatomy and function.

Administration, Inhalation↗

PubMed2005

Computed tomography to visualize and quantify the plantar aponeurosis and flexor hallucis longus tendon in the diabetic foot.

BACKGROUND: The purposes of this report were to describe a three-dimensional computed tomography based method to visualize and quantify the thickness of the plantar aponeurosis and flexor hallucis longus tendon and determine the reliability of thickness measures. Given reliable measures, a secondary purpose was to compare plantar aponeurosis and flexor hallucis longus thickness in subjects with diabetes mellitus and peripheral neuropathy to an age and weight matched group without diabetes. METHODS: CT data from 16 people with diabetes mellitus and peripheral neuropathy (mean age 55.2 (SD 10.5), 4 female, 12 male, body mass index 31.7 (SD 7.6)) and 10 people without diabetes mellitus (mean age 53.8 (SD 9.1), 2 female, 8 male, body mass index 37.0 (SD 8.6)) were analyzed. Length and thickness of the plantar aponeurosis and flexor hallucis longus tendon were measured twice for five subjects from each group in a blinded single observer reliability study. FINDINGS: The average mean difference of the linear measurements was 0.12 mm (average SD=1.00 mm). Significant differences for measures of plantar aponeurosis thickness (p=0.044) were found between diabetic, 4.2 mm (SD 0.9), and control groups, 3.6 mm (SD 0.8), and approached significance for tendon thickness measured at the midfoot (diabetic group 4.8 mm (SD 0.8), control group 4.3 mm (SD 0.8), p=0.051). INTERPRETATION: CT was shown to be a reliable imaging technique for visualizing and quantifying soft tissue structures in diabetic feet. The methods and the quantitative description of the plantar aponeurosis and tendon thickness reported in this paper may be useful to those developing three-dimensional computational models of the foot.

Diabetic Foot↗

PubMed2005

Speech, cognitive, and behavioral outcomes in nonsyndromic craniosynostosis.

BACKGROUND: The neuropsychological morbidity of nonsyndromic craniosynostosis is incompletely understood. The purpose of this study was to establish the prevalence of speech-language, cognitive, and behavioral abnormalities in this population and to stratify the findings on the basis of the affected suture and age of diagnosis with speech-language or psychological abnormalities. METHODS: Charts of all patients with nonsyndromic craniosynostosis evaluated between 1978 and 2000 were reviewed, noting diagnoses of speech-language, cognitive, or behavioral abnormalities. Findings were statistically analyzed for variance with regard to affected suture and diagnosis of abnormalities. RESULTS: Two hundred fourteen patients with nonsyndromic craniosynostosis had documented follow-up evaluations with an average age of 6 years 4 months at last visit. Speech, cognitive, and/or behavioral abnormalities were manifest in 49 percent of the patients with specific rates for each suture as follows: right unilateral coronal, 61 percent; bilateral coronal, 55 percent; multiple, 47 percent; metopic, 57 percent; left unilateral coronal, 52 percent; lambdoid, 44 percent; and sagittal, 39 percent. This prevalence of abnormalities was a statistically significant increase from the general population. Logistic regression demonstrated that as patient age increased, the percentage of abnormal diagnoses also increased. CONCLUSIONS: Nonsyndromic craniosynostosis is often associated with cognitive, speech, and/or behavioral abnormalities. The etiopathology of this association is unknown. Furthermore, the proportion of children diagnosed with cognitive and behavioral dysfunction increases with age. Therefore, longitudinal cognitive, behavioral, and speech assessment and treatment are integral to the care of these patients.

Child↗

PubMed2005

Power injection of microcatheters: an in vitro comparison.

PURPOSE: To determine the tolerance of 0.021-inch and 0.027-inch microcatheters to power injection in an in vitro flow model. MATERIALS AND METHODS: Twenty-four microcatheters (0.021-inch, n = 13; 0.027-inch, n = 11) were injected with iothalamate meglumine through a flow model with use of a power injector and high-pressure tubing. Catheters used included Rebar (0.021-inch, n = 4; 0.027-inch, n = 4), Transit (0.021-inch, n = 3; 0.027-inch, n = 3), Renegade (0.021-inch, n = 4; 0.027-inch, n = 4), and Renegade STC-18 (0.021-inch, n = 2) models. Through the 0.021-inch microcatheters, 5-second injections were performed at an initial rate of 0.7 mL/sec. Injection rates were increased by 0.5 mL/sec and the process was repeated until the pressure approached 1,000 psi or catheter breakage occurred. A similar process was repeated for the 0.027-inch catheters starting at a rate of 3.4 mL/sec. RESULTS: The 0.021-inch catheters were injected 303 times and the 0.027-inch catheters were injected 210 times. Three catheter failures occurred, with all breaks occurring at pressures greater than manufacturer recommendations. The 0.027-inch catheters as a group tolerated significantly higher injection rates than the 0.021-inch catheters. Of the 0.021-inch catheters, the STC-18 also provided superior maximum flow and volume compared with the Renegade catheter. The Rebar catheter tolerated significantly lower maximum injection rates and volumes than the other 0.027-inch catheters. CONCLUSIONS: The majority of microcatheters can be power-injected in vitro at pressures far greater than manufacturer recommendations. When fractures occur, they are near the hub of the catheter. Significantly greater rates of injection are possible through 0.027-inch catheters.

Catheterization↗

PubMed2005

Patient factors affecting thermal lesion size with an impedance-based radiofrequency ablation system.

PURPOSE: To evaluate factors that affect the size of the thermal lesion created from radiofrequency ablation (RFA) with an impedance-based system. MATERIALS AND METHODS: Thirty-two nonresectable liver tumors, including hepatocellular carcinomas (HCC) (N=20; 63%) or metastatic tumors (N=12; 37%) were treated in 29 patients with an impedance based RFA system. Tumor diameter was measured at pre-procedure cross sectional imaging. Follow-up imaging was obtained at 1 month and every 3 months afterward to determine the short axis of the resultant thermal lesion. Success at durable tumor destruction was tracked as well as size of the resulting thermal lesion and the resulting thermal lesion/electrode ratio. Time to impedance roll-off was also correlated with treatment success. RESULTS: Twenty-eight (88%) of the 32 tumors were durably ablated in a single session. Two patients had residual disease and two had local recurrence. All residual or recurrent lesions were in patients with cirrhosis. Three of these patients were retreated resulting in a durable result in 97% of lesions with a mean/median follow up 443/503 days. Mean tumor diameter and resulting thermal lesion size was similar for HCC and metastatic lesions. A significant difference (P=.02) was observed when comparing the thermal lesion/electrode ratios of HCC (1.01+/-0.36) with metastases (1.26+/-0.22). Nine of 20 HCC ablations (45%) resulted in a ratio>1.0, whereas 11 of 12 metastatic ablations (92%) attained a ratio>1.0 (P=.01). Thermal lesion size did not correlate with time to impedance roll-off for the entire group (r=-0.22; P=.90) or by tumor type (HCC r=0.10; P=.68; metastases r=-0.36; P=.23). CONCLUSION: Thermal lesion size and the ability to obtain a margin of normal tissue are significantly affected by the presence of cirrhosis when using an impedance-based system. Given this limitation, the majority of small hepatic neoplasms can still be successfully treated with RFA.

Adult↗

PubMed2005

Hepatic arterial chemoembolization for hepatocellular carcinoma: comparison of survival rates with different embolic agents.

PURPOSE: The optimal embolic agent for transhepatic arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) has not been identified. This study reports outcomes of TACE for HCC with Gelfoam powder and polyvinyl alcohol (PVA). MATERIALS AND METHODS: Eighty-one patients underwent 152 TACE sessions with Gelfoam powder (n = 41) or polyvinyl alcohol (PVA) and Ethiodol (n = 40) as the embolic agent. Chemotherapeutic drugs were the same for all patients (50 mg cisplatin, 20 mg doxorubicin, 10 mg mitomycin-c). The groups were compared based on number of TACE sessions, maximum tumor size, bilirubin level, aspartate and alanine aminotransferase levels, Child-Pugh score, Model for End-stage Liver Disease score, and hepatitis B or C virus positivity. The number of cases of each Child class in each group was also evaluated. Survival starting from the first TACE session was calculated according to Kaplan-Meier analysis. Forty-eight patients died during the study period, 19 received transplants, and 14 were alive at the end of the study period. RESULTS: The groups were statistically similar in all categories regarding liver function, Child-Pugh score, tumor size, hepatitis status, and percentage of patients with Child class A, B, and C disease. The number of TACE sessions was significantly greater for the Gelfoam powder group (mean, 2.2) versus the PVA group (mean, 1.6; P = .01). Overall survival was similar between groups whether patients who received transplants were included in the analysis (mean, 659 days +/- 83 with Gelfoam powder vs 565 days +/- 71 with PVA; P = .42) or were excluded (mean, 519 days +/- 80 with Gelfoam powder vs 511 days +/- 75 with PVA; P = .93). CONCLUSION: In similar patient groups, survival after treatment of HCC with TACE with Gelfoam powder or PVA and Ethiodol was similar.

Antineoplastic Agents↗

PubMed2005

Quantifying effects of plaque structure and material properties on stress distributions in human atherosclerotic plaques using 3D FSI models.

BACKGROUND: Atherosclerotic plaques may rupture without warning and cause acute cardiovascular syndromes such as heart attack and stroke. Methods to assess plaque vulnerability noninvasively and predict possible plaque rupture are urgently needed. METHOD: MRI-based three-dimensional unsteady models for human atherosclerotic plaques with multi-component plaque structure and fluid-structure interactions are introduced to perform mechanical analysis for human atherosclerotic plaques. RESULTS: Stress variations on critical sites such as a thin cap in the plaque can be 300% higher than that at other normal sites. Large calcification block considerably changes stress/strain distributions. Stiffness variations of plaque components (50% reduction or 100% increase) may affect maximal stress values by 20-50%. Plaque cap erosion causes almost no change on maximal stress level at the cap, but leads to 50% increase in maximal strain value. CONCLUSIONS: Effects caused by atherosclerotic plaque structure, cap thickness and erosion, material properties, and pulsating pressure conditions on stress/strain distributions in the plaque are quantified by extensive computational case studies and parameter evaluations. Computational mechanical analysis has good potential to improve accuracy of plaque vulnerability assessment.

Blood Pressure↗