Enhancement Index Research Articles

ENHANCEMENT EVALUATION CRITERIA FOR POOL BOILING ENHANCEMENT STRUCTURES IN ELECTRONICS COOLING: CHF ENHANCEMENT RATIO (ER-CHF) AND ENHANCEMENT INDEX (EI)

Extensive research shows the necessity of efficient cooling systems to enable electronic components to operate at high performance levels for a sustained period. While conventional methods have served the cooling needs so far, rising computational power, energy efficiency, and sustainability requirements call for improved techniques. The literature shows the effectiveness of two-phase systems in cooling electronic components like microprocessors. The literature further describes various enhancement mechanisms to elevate the critical heat flux (CHF) and heat transfer coefficient (HTC) in these systems. While a high CHF is desired, having a high HTC is equally important to keep the operating temperatures below a permissible limit. The present article summarizes enhancement structures found in the literature suitable for electronic cooling to provide this dual enhancement in CHF and HTC. New enhancement evaluation criteria that also consider the surface temperature limit imposed by the electronic components are introduced. The CHF enhancement ratio (ER<sub>CHF</sub>) represents the ratio of CHF for enhancement structures to the CHF for a plain surface, and the enhancement index (EI) represents the ratio of wall superheat at CHF with the enhanced structures to the wall superheat at its respective CHF condition for a plain surface. It is desirable to have a high value of ER<sub>CHF</sub> coupled with a low value of EI (lower the better), preferably below 1.0.

Patterns and Implications of Intracranial Atherosclerosis in Anterior and Posterior Circulation Identified by High-Resolution Vessel Wall Imaging

Introduction: Anterior and posterior circulation atheroscleroses differ in vascular risk factors and stroke patterns. Posterior circulation stroke has worse clinical outcomes. However, few studies described the differentiation of plaque features between anterior and posterior circulation atheroscleroses via high-resolution vessel wall imaging (HR-VWI). We aimed to compare the plaque imaging features between anterior and posterior circulations to highlight the relevance of plaque imaging features to clinical events of ischemic stroke. Methods: Prospective data from a HR-VWI cohort of adult patients with acute ischemic stroke or transient ischemic attack were retrospectively analyzed. Quantitative and qualitative measurements of atherosclerotic plaques along the middle cerebral arteries (MCAs), the basilar artery (BA), and the vertebral arteries (VAs) were conducted on HR-VWI. Vessels with stenotic degrees over 30% were identified on the matched time-of-flight magnetic resonance angiography (TOF-MRA) and visually classified into normal, irregular, stenotic, and occluded. The sensitivity, specificity, positive and negative predictive values for TOF-MRA in detecting abnormal vessels were calculated by using quantification on the basis of HR-VWI findings as the reference standard. Results: One hundred and one patients (median age, 64 years old; 62.4% males) were included in this study. A total of 292 plaques were identified, with 152 in the MCAs, 35 in the BA, and 105 in the VAs. The VAs possessed significantly higher enhancement index (EI) (median 38.37 vs. 18.40, p <0.001), more plaques with positive remodeling (76.2% vs. 57.2%, p = 0.002) and intraplaque hypo-intensity (43.8% vs. 12.5%, p <0.001) than the MCAs. The MCAs presented with more intraplaque hemorrhage (IPH) (20.4% vs. 8.6%, p = 0.014) than the VAs. The sensitivity and specificity of TOF-MRA for evaluating luminal stenosis were 89.0 (82.5–93.4) and 66.7 (24.1–94.0) in anterior circulation, respectively, and were 75.2 (66.7–82.2) and 27.3 (7.3–60.7) in posterior circulation, respectively. Conclusion: Our findings might elucidate the clinical events and outcomes in anterior and posterior circulation stroke. Posterior circulation atherosclerosis had higher EI and more plaques with hypo-intensity, suggesting a heavier atherosclerosis burden. Positive remodeling pattern in posterior circulation atherosclerosis might create an impression of “wider” vascular lumen, leading to possible underestimation of atherosclerosis burden of posterior circulation on TOF-MRA as compared to HR-VWI. Besides, anterior circulation atherosclerosis with IPH might be associated with plaque rupture and artery-to-artery embolism. Future studies are needed to verify these findings.

Early adjunctive diagnostic value of contrast-enhanced ultrasound-related quantitative parameter and its relationship with micro-perfusion of nontraumatic necrosis of femoral head.

The aim of this study is to explore the early diagnostic value of contrast-enhanced ultrasound (CEUS)-related quantitative parameter and its relationship with the micro-perfusion of nontraumatic necrosis of the femoral head. According to the random and double-blind method, the patients with non-traumatic femoral head necrosis diagnosed and treated in our hospital from July 2019 to January 2022 were selected as the subjects (the research group). According to the staging of the International Society of Bone Circulation for Femoral Head Necrosis, 89 patients with stage Ⅱ and Ⅲ A were included (39 patients with stage Ⅱ and 50 patients with stage Ⅲ A). 25 patients who conducted physical examination in our hospital during the same time were taken as the control group. Quantitative parameters of CEUS were analyzed. The content of serum vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) were evaluated. The relationship among the quantitative parameters of CEUS, the expression of VEGF and BMP-2 in serum and the patient's condition, and the value for assisting the early diagnosis of nontraumatic femoral head necrosis were analyzed. The body mass, body mass index (BMI), blood lipid, and cholesterol levels were much higher in the research group than in the control group (p < 0.05). The research group had a markedly higher slope of ascending branch (AS), strength enhancement index (EI), and VEGF and obviously lower decay slope (DS), mean transit time (MTT), and time to peak (TTP) than the control group (p < 0.05). In the research group, compared to stage Ⅱ, the levels of AS, EI, and VEGF in stage Ⅲ A patients were memorably higher, and the levels of DS, MTT, TTP and BMP-2 were dramatically lower (p < 0.05). Pearson's correlation test showed that AS, EI, and VEGF were positively correlated with the patients' condition, while DS, MTT, TTP and BMP-2 were negatively correlated with the patients' condition (p < 0.05). The receiver operating characteristic (ROC) curve analysis showed that the diagnostic area under the curve (AUC) of quantitative parameters of CEUS was 0.961, with sensitivity and specificity of 88.0% and 97.4%, respectively. The AUC of the combined detection of VEGF and BMP-2 was 0.945 with sensitivity and specificity of 82.3% and 87.5%, respectively, and the combined detection had a high diagnostic value (p < 0.05). The quantitative parameters of CEUS were of great value in the early diagnosis of nontraumatic necrosis of the femoral head with microvascular perfusion and the patients' condition, and provided a reference for the clinical treatment of non-traumatic necrosis of the femoral head. These parameters were expected to be useful indicators for judging the efficacy before and after treatment.

T1 and T2 Mapping for Characterization of Mediastinal Masses: A Feasibility study.

Purpose: To evaluate the feasibility and usefulness of T1 and T2 mapping in characterization of mediastinal masses. Methods: From August 2019 through December 2021, 47 patients underwent 3.0-T chest MRI with T1 and post-contrast T1 mapping using modified look-locker inversion recovery sequences and T2 mapping using a T2-prepared single-shot shot steady-state free precession technique. Mean native T1, native T2, and post-contrast T1 values were measured by drawing the region of interest in the mediastinal masses, and enhancement index (EI) was calculated using these values. Results: All mapping images were acquired successfully, without significant artifact. There were 25 thymic epithelial tumors (TETs), 3 schwannomas, 6 lymphomas, and 9 thymic cysts, and 4 other cystic tumors. TET, schwannoma, and lymphoma were grouped together as "solid tumor," to be compared with thymic cysts and other tumors ("cystic tumors"). The mean post-contrast T1 mapping (P < .001), native T2 mapping (P < .001), and EI (P < .001) values showed significant difference between these two groups. Among TETs, high risk TETs (thymoma types B2, B3, and thymic carcinoma) showed significantly higher native T2 mapping values (P = .002) than low risk TETs (thymoma types A, B1, and AB). For all measured variables, interrater reliability was good to excellent (intraclass coefficient [ICC]: .869∼.990) and intrarater reliability was excellent (ICC: .911∼.995). Conclusion: The use of T1 and T2 mapping in MRI of mediastinal masses is feasible and may provide additional information in the evaluation of mediastinal masses.

Revascularization character of autologous fascia lata graft following shoulder superior capsule reconstruction by enhanced magnetic resonance imaging

BackgroundFascia lata has been used for arthroscopic superior capsule reconstruction (ASCR) and verified to achieve a good clinical outcome. However, it is still not known about revascularization character of the fascia lata after ASCR. This study was performed to evaluate the revascularization of autologous fascia lata grafts after ASCR by enhanced magnetic resonance imaging (MRI).MethodsA prospective study of 19 patients with irreparable rotator cuff tears underwent ASCR with autologous fascia lata grafts from September 2019 to April 2021. Radiography examinations and clinical evaluations were performed preoperatively and postoperatively at 6 weeks and 3, 6, and 12 months. The signal-to-noise quotient (SNQ) value and enhancement index (EI) of autologous fascia lata grafts in the great tubercle insertion (GTI), midpoint of the graft (MG), and glenoid insertion (GI) were compared for radiography examination. Clinical evaluation included the American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) shoulder score, and Visual Analog Scale (VAS) score.ResultsThe SNQ values in T1WI enhancement at GI and GTI were significantly higher than those at the plain MRI scan at all postoperative observation timepoints; however, the SNQ values in T1WI enhancement at MG did not show a significant difference until 3 months postoperation. EI values at GTI and GI were significantly higher than those at MG at 6 weeks and 3 months postoperation, while there was no significant difference in the EI value between GTI and GI. At 6 months postoperation, the EI value at GI was significantly higher than those at MG. At 12 months postoperation, the EI value at GI was significantly higher than those at MG and GTI; however, there was no significant difference between GTI and MG. The EI values at GTI and MG peaked at 3 months and 6 months postoperation, respectively, and then plateaued at 12 months postoperation. However, there was no significant difference in the EI value among the different postoperative timepoints at GI. The EI value did not correlate with the VAS and ASES, UCLA scores at any time point or any postoperative observation location.ConclusionRevascularization of the fascia lata was dependent on the location of the fascia lata and plateaus at 12 months postoperation. The EI value did not correlate with the VAS and ASES, UCLA scores during12 months postoperation.

Contrast enhanced magnetic resonance imaging in early assessment of atherosclerotic lesion of abdominal aortic wall and common iliac arteries

Highlights. Early atherosclerotic changes in the abdominal aortic wall and common iliac arteries in patients without clinical manifestations of critical atherosclerotic stenosis of the lower extremity arteries were studied using contrast enhanced magnetic resonance imaging. A method for quantitative characterization of the accumulation of paramagnetic contrast in the abdominal aortic wall and common iliac arteries is presented.Aim. To study the pattern of early atherosclerotic lesions of the abdominal aortic wall and common iliac arteries in patients without clinical manifestations of critical atherosclerotic stenosis of the lower extremity arteries using paramagnetic contrast enhancement (CE-) MRI.Methods. The retrospective study included 36 patients (25 men, 11 women) who underwent MRI of the lumbar spine with CE, without signs of atherosclerosis of the lower extremities. Subsequently, 2.5 and 4 years after CE-MRI, two patients developed acute leg ischemia and required vascular surgeries. At the time of the study, both had higher levels of C-reactive protein in the blood (6.3 mg/L and 5.9 mg/L, while the other patients had &lt;4.2 mg/L). MRI included T2 – and T1-weighted spin-echo scans (T2-w and T1-w) in the axial and sagittal planes, before and in 10-15 minutes after contrast injection. The index of enhancement (IE) of T1-w was calculated based on the ratio of mean intensities of the region of arterial wall over aorta and iliac arteries in CE-MRI and pre-contrast MRI: IE = Int.T1–w. CE / Int. T1–w pre-contrast.Results. Depending on the IE of the abdominal aortic wall in CE-MRI, patients were divided into three groups: group 1 (n = 11) with IE ≤1.05; group 2 (n = 16) with 1.05 &lt;IE ≤1.15; group 3 (n = 9) with IE &gt;1.15. The aortic IE in all three groups was 1,03 (1,01;1,03); 1,10 (1,09;1,15); 1,36 (1,16;1,40) respectively (p&lt;0.001). The thickness of the abdominal aortic wall progressively increased moving up the group 1, while statistically significant differences were found only between the groups 1 and 3, and the groups 2 and 3 (p&lt;0.001). There were no differences in the wall thickness of the common iliac arteries and the diameter of all vessels studied between the groups. Two patients from the group 3 later presented with acute limb ischemia.Conclusion. The state of the abdominal aortic wall and common iliac arteries should be evaluated, and IE of T1-w should be calculated when performing CE-MRI examination of the area of the descending aorta to assess pathological neoangiogenesis as the most important component of atherogenesis.

Symptomatic plaque enhancement is associated with early-onset post-stroke depression

BackgroundThe association between imaging features closely associated with symptomatic intracranial atherosclerotic plaques and early-onset post-stroke depression (PSD) is currently unclear. Materials and methods76 ischemic stroke patients who underwent high-resolution vessel wall magnetic resonance imaging (HR-VWI) were divided into PSD and non-PSD groups according to their DSM-V diagnoses and HAMD-17 scores at 14 days after onset. Clinical data and the imaging features associated with symptomatic plaques (including the enhancement index (EI), remodeling index, and plaque surface irregularity) were compared between groups. Multifactorial logistic regression analysis was used to find independent predictors of early-onset PSD. Spearman rank correlation analysis explores the association between clinical data, symptomatic plaque imaging features, and HAMD-17 in patients. ResultsThe sample comprised 36 patients with early-onset PSD. The symptomatic plaque EI and infarct volume were significantly higher in depressed patients than in patients without depression (P < 0.05). Multivariate logistic regression showed that symptomatic plaque EI could be used as an independent predictor of early-onset PSD after correcting for the confounding factor of infarct volume (OR = 1.034, 95% CI:1.014–1.055, P = 0.001). In the total sample, symptomatic plaque EI, infarct volume, and HAMD-17 had a significant positive correlation with each other (P < 0.05). LimitationsThis study focused only on the patients' symptomatic plaques and did not monitor patients' systemic inflammation levels at the time of HR-VWI. ConclusionsThe degree of symptomatic plaque enhancement is an independent predictive imaging marker of early-onset PSD and can be used the early diagnosis of early-onset PSD.

Renal denervation may attenuate the severity of MRI-signs of vascular wall damage in diabetic patients with resistant hypertension due to the anti-inflammatory effect

Objective . The aim of this study was to investigate the long-term effect of renal denervation (RDN) on MRIcharacteristics of renal artery (RA) wall in diabetic patients with resistant hypertension (RHTN). Design and methods . We included 19 diabetic patients with RHTN (mean age 61,9 ± 6,8 years; 6 men; HbA1c 6,6 ± 1,4 %; mean blood pressure (BP) 24h 159,5 ± 18,9 / 82,2 ± 13,7 mm Hg) who underwent MRI of the RA before and 12 months after RDN. The measurement of signal intensity (SI) of RA wall based on two-dimensional T1-weighted spin-echo images was done before and after the administration of a gadolinium-based contrast agent. The index of enhancement (IE) was calculated as ratio of SI post-to-precontrast enhancement. All patients underwent ambulatory 24-hour (24h) BP monitoring, lab tests (serum hsC-reactive protein (CRP), tumor necrosis factoralpha (TNF-α)) at baseline and 12-month follow-up. On average, patients were taking 4 (3–6) antihypertensive drugs. The mean number of ablations was 13 ± 1,8 (10–16). Patients were instructed not to change the treatment regimen throughout the study. At 12-month follow up MRI of RA was available for 16 patients. Results . After RDN there was a significant comparable decrease in IE of RA wall for both sides (IE mean values for right and left sides: from 1,7 ± 0,4 to 1,4 ± 0,3, p = 0,02 for the main RA; from 1,7 ± 0,5 to 1,4 ± 0,2, p = 0,04 for the middle parts of RA; from 1,9 ± 0,4 to 1,4 ± 0,3, p = 0,001 for distal branches of RA). In addition, RDN reduced the 24h BP (systolic / diastolic) by –15,1/–10,0 mm Hg, p &lt; 0,001 as well as reduced the level of TNF-α (from 4,6 ± 3,8 to 3,4 ± 2,5 pg/ml, p = 0,03) and the level of hsCRP (from 6,5 ± 3,4 to 5,9 ± 3,2mg/L, p = 0,003). There was no direct relation between the IE and BP reduction. At the same time, the change in IE of middle part of RA after RD was directly related to decrease in both hsCRP level (R = 0,62, p = 0,03) and TNF-α level (R = 0,56, p = 0,04). Conclusions . The beneficial effect of RDN on the RA wall is associated with the attenuation of systemic subclinical inflammation.

MRI of the arterial wall in resistant hypertension associated with type 2 diabetes mellitus

BACKGROUND: Damage of arterial walls in diabetes mellitus associated with arterial hypertension is major factor delivering lesion of target organs. Currently, enough data is not available about imaging and quantitative evaluations of arterial wall. There is no enough data available about the relations between MRI and inflammatory and metabolic markers in patients with resistant arterial hypertension concomitant with diabetes mellitus.&#x0D; AIMS: Quantitative assessment of the intensity of paramagnetic contrast enhancement of the arterial wall, in particular renal arteries walls, in relation with inflammatory and metabolic markers in patients with resistant arterial hypertension concomitant with diabetes mellitus.&#x0D; MATERIALS AND METHODS: The study groups were comprised of 28 patients (ageing 60,76,5 years) with resistant hypertension accompanied with diabetes mellitus and 17 patients (aging 57,75,0 years) with resistant hypertension without diabetes mellitus. The average systolic/diastolic pressure obtained from a 24-h monitor study was as high as 156,816,9/81,9,013,5 mm Hg in the group with diabetes and 154,811,9/88,510,4 mm Hg in the group without diabetes. The values of glycaemia, the level of glycated haemoglobin, and C-reactive protein were determined. The MRI studies were carried out using 1,5 Т MRI Toshiba Vantage Titan scanner. After that, the intravenous contrast enhancement has been carried out (with 0,5 М paramagnetic, as 0,2 ml/Kg). The index of enhancement (IE) was then calculated from these data, as a ratio of intensities of contrast-enhanced image to the initial nonenhanced MRI scan.&#x0D; RESULTS: The correlation was obtained for IE of arterial wall and data of blood pressure. Increased IE was correlated with ageing and hemodynamic factors. Also the correlation was observed for IE proximal, medium and distal parts of renal arteries and values of glycaemia and NOMA-index were obtained. Negatively correlated values for IE and adiponectin in the group with diabetes mellitus were obtained. The association between IE and C-reactive protein remained significant in the group without diabetes mellitus.&#x0D; CONCLUSIONS: MRI with contrast enhancement of arterial walls allows evaluating the anatomy of renal arteries and allows quantifying the pathophysiologic factors of their walls in patients with resistant hypertension accompanied with diabetes mellitus. MRI characteristics of the arterial wall were associated not only with hemodynamic and metabolic data, but also with markers of inflammation.

Contrast enhanced magnetic resonance imaging in assessment of aortic atherosclerosis and its relation to severity of myocardial injury due to infarction

Aim. To study the contrast enhanced magnetic resonance imaging (CE-MRI) role in assessment of aortic atherosclerosis and its relation to severity of myocardial injury in myocardial infarction (MI) patients which underwent cardiac MRI before coronary artery bypass grafting and Dor or Menicanti procedures.Material and methods. The study included 42 patients (38 men, 4 women) who underwent CE-MRI (mean age 57,7±8,75 years). In order to analyze the aortic atherosclerosis, axial T1 weighted images before and after 10-15 minutes after CE was evaluated. Along with visual analysis, the diameter, thickness of the aortic wall, and index of enhancement (IE) of T1 weighted image (WI) (TR=400-650 ms, TE=12-20 ms), as the ratio of postand precontrast intensities of the aortic wall: IE=(Intensity T1-WI post-contrast)/ (Intensity T1-WI pre-contrast) were determined. According to the cardiac CEMRI, the proportion of left ventricle (LV) injury as the ratio of the MI injury and theLV mass was estimated.Results. Depending on aortic IE value, patients were divided into three groups: group 1 (9 people) with IE ≤1,05; group 2 (15 people) with 1,05&lt; IE ≤1,15; group 3 (18 people) with IE &gt;1,15. We compared the descending aortic wall thickness and the diameter among these groups. To identify intergroup differences one-way ANOVA with Bonferroni correction was carried out. There were no significant differences in the descending aortic diameters (F=0,15; p=0,86): group 1 — 2,41±0,33, group 2 — 2,54±0,63, group 3 — 2,53±0,51 cm. The thickness of the aortic wall in groups was 2,05±0,58 mm, 3,34±0,68 mm and 3,80±0,46 mm (F=17,39; p&lt; 0,001), respectively. The first and second, first and third groups were distinguished, and there was no significant difference between the second and third groups. Between groups 1, 2 and 3 were also noted the increase and differences in proportion of LV injury, which amounted to 0,11±0,03 with a minimum IE (group 1), with an intermediate IE (group 2) — 0,19±0,08, and with high IE — 0,25±0,15.Conclusion. CE-MRI of the aortic wall can be used as a method of visualizing atherosclerosis and predicting the complications of aortic atherosclerosis. Moreover, the assessment of aortic atherosclerosis can be used in combination with conventional heart examination. The increased CE into the aortic wall in patients with advanced atherosclerosis is usually associated with a greater severity of myocardial injury. During cardiac CE-MRI it is advisable to assess the descending aorta state by calculation of IE T1-WI MRI to clarify the atherosclerosis severity and cardiovascular risk.

MRI with paramagnetic contrast enhancement of the arterial vascular wall in follow-up control of therapeutic effect in resistant arterial hypertension treated with radiofrequency ablation of sympathetic plexus of the renal arteries

Aim . Quantitative follow-up of the intensity of paramagnetic contrast enhancement of the aortal wall and renal arteries walls, as indicator of the pathological subinitimal and media neoangiogenesis was carried out in patients with arterial hypertension, focusing on changes after renal denervation. Material and methods . 31 patients (as old as 57.3 ± 9.8 years) with resistant hypertension comprised the study group. The average systolic/diastolic pressure obtained from 24-h monitor study was as high as 154 ± 12 / 89 ± 9 mm Hg. The MRI studies were carried out using 1.5 Т MRI Toshiba Vantage Titan scanner. After this the intravenous contrast enhancement has been carried out (with 0.5 М paramagnetic, as 0.2 ml/Kg). The radiofrequency ablation (RFA) desympathising the kidneys was performed on X-ray operating room using the Symplicity system: Symplicity Flex renal ablation electrode with a 4F end electrode as thin as 1.33 mm and with length of 1.5 mm, and also automated RF voltage generator with built-in power management algorithms temperature (Medtronic, USA) were employed. The comparison group included 28 people who were referred for MRI study of lumbar spine (average age - 53.2 ± 17.8), without any evidence that could be attributed to the pathology of the cardiovascular system. Results . Enhancement index (EI) of the aortic wall of patients with hypertension (1.57) was significantly over the aortic EI of healthy people (1.23), p < 0.0001, reflecting inflammatory neoangiogenetic changes in the vascular wall in hypertension. The correlation between EI in the wall of both renal arteries is highly reliable and linear, which confirms the idea of the systemic nature of neoangiogenesis in hypertension. Analysis of data from an MRI study of the renal arteries showed that the intensity of the accumulation of the contrast agent in their wall after RD, as a rule, decreases (the right RA distal segment 1.78, 1.61, 1.59 - at baseline, at 6 and 12 months after RD, respectively (p < 0.05). Thus, a visual MRI proves electro-induced damage to the wall of the renal artery and the development of fibrosis at the site of radiofrequency exposure. At the same time, there are no significant differences in EI between studies at the sixth (p = 0.56) and twelfth (p = 0.48) months of observation after RFA, which argues in favor of maintaining fibrosis and, respectively, the absence of reinnervation and inflammatory neoangiogenesis of the arterial wall. Conclusion. MR-tomographic examination of the aorta and renal arteries with contrast enhancement should be carried out to assess the state of the walls of these vessels and to dynamically monitor their condition after renal denervation.

Quantitative Analysis of the Characteristics of Sacral Giant Cell Tumors Using Contrast-Enhanced Computed Tomography

Background: Although CT morphological characteristics of giant cell tumors (GCTs) of the sacrum have been reported in the literature, the enhanced CT quantitative characteristics of GCTs have not been extensively evaluated. Objectives: The aim of our study was to analyze the enhancement characteristics of giant cell tumors of the sacrum. Patients and Methods: Sixty-one cases were reviewed, including 20 GCTs, 22 sacral chordomas (SCs) and 19 sacral schwannomas (SSs). The CT images of all the three types of tumors were retrospectively analyzed. The enhancement index (EI) of each mass was calculated by the formula: EI(a/v) = [D(a/v) - D(pre)]/D(pre), where D(a/v) was the density of the mass on the enhanced CT (a = arterial phase; v = portal venous phase), and D(pre) was the density of the mass on the pre-enhanced images. The maximum enhancement (Emax) was determined by the following equation: Emax = D(v) - D(pre). The parameters of the different enhancement phases among the 3 groups were compared with One-way ANOVA. Results: On the noncontrast images, the densities of the SCs were lower than those of the GCTs and SSs, but there was no difference between the GCTs and SSs (P > 0.05). In the arterial phase, the EIa of the GCTs was the highest among the three groups (P < 0.05), and that of the SCs was the lowest. In the venous phase, the EIv of the GCTs was higher than that in the arterial phase and was also the highest among the three groups (P < 0.05). A difference was found among the groups, namely, the GCTs, SCs, and SSs (P < 0.05). The EIa and EIv of the SCs were the lowest among the three groups. The Emax of the GCTs was the highest among the three groups (P < 0.05). Conclusion: Quantitative analysis of the characteristics of contrast-enhanced CT is a useful method for diagnosing sacral GCTs and differentiating these tumors from SCs and SSs.

Contrast-enhanced MRI of aortal atherosclerosis: syndrome types and prediction of dissection

Methods The patients population comprised 33 patients (pts, 31 men, 2 women, aged 57±9 years) with extensive atherosclerosis and old transmural acute myocardial infarction (AMI) of the left ventricle. All pts underwent cardiac CE MRI before coronary artery bypass surgery. As a control group eight patients with tumor pathology of the chest without evidence of clinically significant atherosclerosis were employed (aged 53±8 years). In addition to the CE MRI of the heart, the CE MRI of atherosclerotic lesions of the aorta was carried out. Before and in 15-20 minutes after the injection of paramagnetic contrast agent T1weighted spin-echo images (TR=450-600 ms, TE=15 ms) were acquired. Geometric diameter and wall thickness of the aorta at the level of uptaken of contrast-paramagnetic agent to the wall, and index of enhancement (IE) were also measured.

Triple-phase dynamic MRI: A new clue to predict malignant transformation of giant cell tumor of bone

ObjectiveOur purpose was, through the comparison of the characteristics of time–intensity curve on triple-phase dynamic contrast-enhanced MRI among groups of giant cell tumor of bone (GCTB), recurrent benign giant cell tumor of bone (RBGCTB), and secondary malignant giant cell tumor of bone (SMGCTB), to find clues to predict the malignant transformation of GCTB. Subjects and methods21 patients diagnosed as GCTB were included in this study. All cases took recurrence after intralesional curettage. 9 cases were confirmed as SMGCTB and 12 cases were confirmed as RBGCTB. Cases were divided into four groups: group A, GCTB (n=9); group B, SMGCTB (n=9); group C, GCTB (n=12); group D, RBGCTB (n=12). Enhancement index(EI) of lesions on DCEMRI was calculated using formula: EI(t)=[S(t)−S(0)]/S(0), where S(0) was signal intensity of lesion on non-contrast-enhanced T1-weighted images and S(t) was signal intensity of lesion on DCEMRI (t=30, 60, 180s). Enhancement index of each group in each phase was compared using One-Way ANOVA analysis. Slope values of time–intensity curve were compared by the same way. ResultsTime–intensity curve of SMGCTB was characterized by a steep upward slope followed by an early and rapid washout phase. Time–intensity curve of GCTB and RBGCTB was characterized by a steep slope followed by a relatively slow washout phase. No significant difference in enhancement index was found in the first phase (p>0.05). There was significant difference in the second and the third phase (p<0.05). Enhancement index of group B (SMGCTB) was smaller. There was no difference in rising slope value (p>0.05). ConclusionsDynamic contrast-enhanced MRI appears a helpful method to find new clues to predict malignant transformation of GCTB.

Triple-phase dynamic MRI of intratumoral vessel density and hyalinization grade in uterine leiomyomas.

Our purpose was to clarify the relationship between the tissue vascularity shown on triple-phase dynamic MRI and the number of intratumoral vessels and degree of hyalinization, which are two histopathologic changes in leiomyoma. SUBJECTS AND METHODS. The subjects were 10 premenopausal patients with 20 leiomyomas who had undergone surgery without preoperative gonadotropin-releasing hormone analogue treatment. Intratumoral vessel density was determined by the mean number of intratumoral vessels with at least one smooth-muscle layer in the optic fields magnified 100 times. Hyalinization grade was determined by the severity of hyalinization, histopathologically classified in three grades. The enhancement index (EI) of the leiomyoma was calculated using the formula EI(t) = [S(t) - S(0)] / S(0), where S(0) is the signal intensity on pre-enhanced T1-weighted images and S(t) is the signal intensity on each dynamic phase image (t = 20, 60, and 180 sec) [corrected]. The histopathologic parameters of intratumoral vessel density and hyalinization grade were compared with the enhancement indexes obtained from the triple-phase dynamic MRI. We found positive correlations between intratumoral vessel density and EI(60) and between intratumoral vessel density and EI(180) (in both cases, p = 0.0028 and r = 0.69). We found significant differences among the mean enhancement indexes for each hyalinization grade at all dynamic phases (p < 0.01). The leiomyomas with lower intratumoral vessel densities tended to show greater hyalinization. Our results showed that leiomyomas with only slight hyalinization or with abundant vessels were well enhanced, but the leiomyomas with severe hyalinization enhanced poorly.

Microvessel density of malignant and benign hepatic lesions and MRI evaluation.

To study the difference of microvessel density (MVD) between malignant and benign hepatic lesions and study the relationship between MVD and dynamic enhanced magnetic resonance imaging (MRI) for evaluation of microvessels within malignant and benign hepatic lesions. A total of 265 specimens of hepatocellular carcinoma (HCC), 122 cirrhosis tissues and 22 hepatic benign lesions were enrolled for MVD by immunohistochemistry on tissue microarray, of which 49 underwent MRI examination before surgery, then contrast-to-noise ratios (CNR) and enhancement index (EI) in all the phases were calculated. Pearson correlation was performed for correlation analysis between CNR, EI and MVD. MVD of HCC was 22.7+/-15.8 (mean+/-SD), which was obviously higher than that of cirrhosis tissue (8.3+/-7.6, P<0.01), but was not statistically different from that of benign lesions (31.3+/-22.7, P>0.05). Among HCC, MVD of grades I-II was 29.9+/-18.6, which was much higher than those of grade III (22.2+/-18.2, P<0.01) and grade IV (22.9+/-19.0, P<0.01). MVD of HCC (P=0.018) and of benign lesions (P=0.014) were both correlative with CNR in arterial phase. Neoangiogenesis is an important feature for malignant tumor, and MVD may act as a biological marker in differentiating malignant from benign hepatic lesions. Dynamic enhanced MRI, especially image in arterial phase, may act as an MVD evaluation criterion for malignant and benign hepatic lesions.

Effect of d-limonene on the transdermal permeation of nifedipine and domperidone

The aim of this research is to study the profile of transdermal permeation of nifedipine and domperidone. Permeation studies were carried out using the skin of hairless rat and human skin as a membrane mounted in a permeation system in vitro. The influence of the type of skin used and the presence of d-limonene on the transdermal penetration of these drugs were studied. The drugs studied permeate approx. 3 times faster through rat skin than through human skin. The type of skin has no influence on the lag time. d-Limonene increases the values of the permeability constant ( K p), flux ( J) and lag time ( t 1) for both drugs, but not the lag time for domperidone when human skin is used. The effect of the enhancer on the enhancement index (EI) of domperidone varies with the type of skin used ( EI = 15.7 (rat skin) and EI = 7.7 (human skin). When human skin is used, although penetration is increased by d-limonene, the concentration values predicted at steady state are below therapeutic levels for both studied drugs.

The enhancement index concept applied to terpene penetration enhancers for human skin and model lipophilic (oestradiol) and hydrophilic (5-fluorouracil) drugs

A series of cyclic monoterpenes has been assessed as skin penetration enhancers towards a model lipophilic drug, oestradiol. In vitro permeation experiments on human epidermal membranes showed that the terpenes varied in their activities; hydrocarbon (e.g., limonene) and cyclic ether (e.g., 1,8-cineole) terpenes were effective accelerants providing approximately 4-fold increases in the permeability coefficient of aqueous oestradiol, whereas alcohols (e.g., carveol), ketones (e.g., menthone) and epoxides (e.g., pinene oxide) were ineffective. The results of this study are compared with terpene activities towards a model hydrophilic drug, 5-fluorouracil. A novel concept, the enhancement index (EI), is introduced to compare differences in terpene activities towards the two permeants; EI provides information as to the partition coefficient and maximum achievable permeation enhancement for a drug, together with a measure of a penetration enhancer's activity towards that drug expressed as a percentage of the maximum effect. This approach permits useful comparisons between the activities of various enhancers towards different drugs.