Sergio X. Salles-Cunha

Assessment of deep venous thrombosis by grayscale median analysis of ultrasound images.

Aim: This study aimed to determine whether grayscale median (GSM) ultrasound (US) analysis could differentiate acute from subacute femoropopliteal deep venous thrombosis (DVT) classified based on (a) the time of symptoms onset and (b) sonographers evaluation of US images. Methods: Patients who had US because of suspected DVT were included. Patients with history of previous DVT, with normal US results or US with findings of isolated calf thrombosis were excluded. A total of 128 venous segments of 63 patients were analyzed. Thrombosed veins and adjacent arteries images were recorded. Thrombi GSM were calculated. Grayscale median was compared with (a) the time of symptoms onset and (b) US image thrombi classification as acute or subacute done by 2 sonographers blinded to patient information. Statistical analysis included GSM Pearson intraobserver variability and t test comparisons of GSM means for (a) short versus long onset periods and (b) acute versus subacute US class, &khgr;2 comparison between onset history and US class, creation of GSM accuracy, predictive values, and sensitivity curves for acute versus subacute DVT. Results: Intraobserver variability correlation varied between 0.92 and 0.95. Thrombus mean GSM was 23 ± 12 versus 31 ± 16 if symptoms onset was shorter or longer than 2 weeks (P = 0.004). Mean GSM was 20 ± 11 versus 35 ± 14 for acute versus subacute thrombi (P < 0.001). Acute thrombi correlated with onset shorter than 2 weeks (P < 0.001). Grayscale median less than 13, equal to 22, or 33 or less had 85% positive predictive value (17/20), 77% accuracy (98/128), and 90% sensitivity (53/59) to differentiate acute from subacute thrombi. Conclusions: Grayscale median of US images documenting femoropopliteal DVT correlated with (a) the time between symptoms onset and US examination and (b) the sonographers interpretation of acute versus subacute thrombosis.

Ultrasonographic Tissue Characterization of Kidneys in Patients with Unilateral Renal Artery Stenosis

Introduction Ultrasound tissue characterization (USTC) has been applied to B-mode images of normal, young and transplanted kidneys, carotid, and peripheral atherosclerosis and venous thrombosis. We analyzed USTC from both kidneys of patients with severe unilateral renal artery stenosis. Seven women and 11 men, 79 ± 9 standard deviation (range = 57–96) years of age, were included. Severe, unilateral, renal artery stenosis was based on renal artery peak-systolic velocity (PSV) > 200 cm/sec and/or renal-aortic PSV ratio > 3.5. This sample population, selected sequentially by date of ultrasonographic examinations requested, was heterogeneous: kidney lengths and resistivity indices varied from 6.7 to 13.4 cm and 0.45 to 0.85. Methods USTC was applied to images selected for kidney length measurements. Pixel brightness in the 0–255 range was rescaled to zero for black and 200 for fascia brightness. Gray-scale medians (GSM) of entire kidneys were estimated for statistical comparisons between: (a) kidneys ipsilateral to stenosis (KIS), (b) kidneys contralateral to stenosis (KCS), and (c) normal, young kidneys (KN), previously published GSM = 37 ± 6 (27–48). Results Two distinct KCS subgroups were identified: (1) near-normal GSM < 54 (KCSN, n = 10, 56%); and (2) elevated GSM > 60 (KCSH, n = 8, 44%). Subgroup increasing GSM order was (1) KN, (2) KCSN (47 ± 7, > KN, p < 0.002), (3) KIS-CN (59 ± 20, >KCSN, p < 0.003), (4) KIS-CH (73 ± 20, > KCSN, p < 0.007), and (5) KCSH (78 ± 17, >KIS-CN, p < 0.05). GSM was independent of kidney length or resistivity index, with Pearson correlation coefficients < 0.5 for either KIS or KCS, respectively. Conclusions Tissue echogenicity, represented by GSM, was an independent variable characterizing effects of unilateral renal artery stenosis on the ipsilateral or on both kidneys.

Initial Evaluation of Virtual Histology Ultrasonographic Techniques Applied to a Case of Renal Transplant

Ultrasound virtual histology (USVH) techniques have been applied to B-mode images of coronary, carotid, and peripheral arteries and to deep venous thrombosis. We expanded USVH to evaluate the kidney. This case reports USVH applied to a renal transplant. A 29-year-old male with chronic renal insufficiency received his sisters kidney. B-mode images were recorded during (a) routine 1-day posttransplant US examination; and (b) a second follow-up US performed 6 days later once the patient became symptomatic. B-mode brightness of each pixel was classified into 14 ranges. USVH demonstrated high echogenicity of the kidney on day 1; gray scale median, GSM = 60, was elevated when compared with average GSM = 37 for normal, young kidneys. Muscle-like plus fiber-like echoes, 46 + 10 = 56%, were higher than expected for a normal young kidney, 34 + 3 = 37% (p = 0.0071). GSM increased to 88 on day 7. Normal resistivity indices (RI) on day 1 increased from 0.66–0.70 to 0.81–0.90. Biopsy confirmed kidney rejection. These findings confirmed the concepts that tissue changed before hemodynamics were altered and signs and symptoms developed. Ultrasonographic tissue characterization, particularly of transplanted kidneys, deserves extensive investigation focused on early changes that precede present-day detectable abnormalities.

Diastolic Ankle-Brachial Indices as a Complementary Measure to Screen for Peripheral Arterial Disease in Diabetic Patients

Introduction Ankle-brachial systolic pressure ratio or Index (ABI or ABI-S) has influenced cardiovascular screening for decades. Total or partial rigidity (i.e. calcification) of tibial arteries has hampered Doppler ABI-S measurements in patients with diabetes. Diastolic pressures are measurable with the oscillometric technique. The authors of a previous study demonstrated that ABI-D (ankle-brachial index based on diastolic pressure ratio) was less sensitive than ABI-S, but partial or total incompressibility of tibial arteries was suspected if ABI-D < ABI-S. This study examined whether ABI-D added information to screen for peripheral arterial disease (PAD) in patients with diabetes. Methods An “eye-to-foot” screening/educational program was performed at the city of Arapiraca, state of Alagoas, northeast of Brazil. A vascular surgeon, an expert on the diabetic foot, selected subjects with decreased pulse and/or older age. Bilateral arm and ankle pressures were performed in 71 diabetic patients: 47 (66%) women and 24 (34%) men, 68 ± 10 years (range, 46–86). ABI-S and ABI-D were calculated on the basis of bilateral brachial and ankle oscillometric pressures. Screening for PAD was compared on the basis of the prevalence of ABI < 0.90. Results ABI-S, ABI-D, or either ABI < 0.90 were detected in 36 (51%), 48 (68%), and 55 (77%) diabetics, respectively. ABI-S and ABI-D, only ABI-S, or only ABI-D were <0.90 in 53% (n = 29), 13% (n = 7), and 35% (n = 19) of the 55 diabetics with ABI < 0.90. The increase in frequency of ABI < 0.90 was significant if ABI-D complemented ABI-S (p < 0.001 by chi-square). ABI-D and ABI-S were 0.83 ± 0.06 (0.68–0.895) versus 1.01 ± 0.10 (0.92–1.30) in the only ABI-D < 0.90 group. Conclusions Diastolic ankle pressures were estimated successfully by use of the oscillometric technique. Diastolic ABI correlated with expert physician assessment and contributed to quantitative screening for PAD in diabetic patients with apparently falsely elevated systolic ABI caused by partial incompressibility of tibial arteries.

Technology Dependence of Intima-Media Thickness Ultrasonographic Measurements

Introduction Ultrasonographic (US) measurements of intima-media thickness (IMT), particularly of the carotid arteries, have been used as a cardiovascular risk assessment tool. Variations in manual and semiautomatic measurements were investigated in an animal model—the aorta of 10 rabbits with dyslipedemia. Methods IMT was measured in B-mode images with 256 shades of gray using a 10 MHz probe by two independent investigators: (a) three same-place manual measurements were averaged in five distinct locations of the aorta of each rabbit for a total of 50 measurements per investigator (subgroups M1 and M2); (b) experimental software allowed for alterations in blood-intima and media-adventitia brightness line definition for IMT detection; observer 1 used brightness 50–200, adaptable to all images (SA1); observer 2 started with 10–60—the usual for human carotid measurements in this package—and increased values until IMT lines were visually acceptable; IMT was measured at optimized values for each image (SA2). Mean values were compared by using the paired t-test available in Excel. Results SA1 measurements, 0.379 ± 0.112 (SD) mm, were significantly smaller than SA2, 0.403 ± 0.122 mm, M1, 0.404 ± 0.149 mm, and M2, 0.405 ± 0.140 mm (<0.001 for all three SA1 versus SA2, M1 and M2 comparisons). Conclusion/Discussion Distinct automatic technologies, including (a) selection of blood-intima and media-adventitia brightness interfaces and (b) signal processing to “improve” line images, may alter IMT measurements significantly. Assumed population variations may be affected by technology used. IMT gender and age tables may be applicable only if the same measurement technology was used consistently.