Analysis of optical absorbance spectra for the determination of ZnO nanoparticle size distribution, solubility, and surface energy.

We present a model to calculate particle size distributions (PSDs) of colloidal ZnO nanoparticles from their absorbance spectra. Using literature values for the optical properties of bulk ZnO and correlating the measurement wavelengths in the UV-visible regime with distinct particle sizes by a tight binding model (TBM), an algorithm deconvolutes the absorbance spectra into contributions from size fractions. We find an excellent agreement between size distributions determined from TEM images and the calculated PSDs. For further validation, bimodal PSDs have been investigated and an approach to determine not only particle size but also solid concentration is introduced. We will show the applicability of our model by the determination of temperature-dependent ripening rates, which enables the calculation of solubilities, surface tensions, and the activation enthalpy of ripening. In principle, our methodology is applicable to different semiconductor nanoparticles in various solvents as long as their bulk properties are known and scattering is negligible.

Diagnostic accuracy of cardiac 64-slice computed tomography in detecting atrial thrombi. Comparative study with transesophageal echocardiography and cardiac surgery.

OBJECTIVES: Atrial thrombi are a potential source for cerebral and peripheral emboli. Objective of this study was to evaluate the diagnostic accuracy of 64-slice cardiac computed tomography (CT) for detection of atrial thrombi in comparison with transesophageal echocardiography (TEE) and cardiac surgery. MATERIAL AND METHODS: Sixty-four patients were examined with ECG-gated multidetector CT coronary or pulmonary vein angiography. All patients underwent TEE. Cardiac surgery was performed in 31 patients. The Hounsfield units (HU) of atrial lesions were measured. RESULTS: The diagnostic accuracy of 64-slice CT for the detection of atrial thrombi was 77%: sensitivity 100% (9/9), specificity 73% (40/55), positive predictive value (PPV) 38% (9/24), and negative predictive value (NPV) 100% (40/40). All 15 false positive (FP) findings by CT were located in the left atrial appendage (LAA). Four characteristic imaging features suggesting incomplete filling of the LAA were noted in FP: "hypostatic layering," 5/15 (33%); "flow phenomenon," 9/15 (60%); "HU-run-off," 8/15 (53%); higher intralesional HU in FP when compared with thrombi (153.8 HU +/- 71 vs. 46.6 HU +/- 10; P < 0.0001). The diagnostic accuracy of CT in detecting atrial thrombi improved significantly (P = 0.03) to 86% after defining "typical filling defects" as "flow phenomenon/>180 HU" (sensitivity 100%; specificity 84%; PPV 50%; NPV 100%). On receiver operating curve (ROC) analysis, a threshold of 60.7 HU showed a specificity of 100% and a sensitivity of 86.7% to distinguish between FP and thrombi. CONCLUSIONS: Cardiac ECG-gated 64-slice CT is accurate to exclude atrial thrombi, which can be applied eg, in patients before radiofrequency (RF) ablation. Left atrial appendage "filling defects" cause a high number of false positive findings, and there are radiologic features, which are helpful to differentiate them from true thrombi.

Assessment of the intratesticular resistive index by colour Doppler ultrasonography measurements as a predictor of spermatogenesis.

OBJECTIVE: To investigate the value of the resistive index (RI) of intratesticular arteries, and to establish diagnostic criteria for normal and pathological sperm counts on the basis of quantitative colour Doppler ultrasonography (CDUS), as the assessment of the testicular RI is widely used to measure intratesticular blood flow. PATIENTS AND METHODS: In all, 160 men (aged 22-43 years, 320 testicles) were prospectively investigated; 80 had a normal and 80 a pathological sperm count, the latter having mild oligoasthenozoospermia. The RI was measured using a high-frequency Doppler ultrasound probe (14 MHz), three times on each testicle at an intratesticular artery in the upper, middle and lower testicular pole. The testicular volume was also measured by US. The RI values were compared between patients with normal and pathological sperm counts, and were compared statistically with testicular volumes. In addition, blood samples were obtained for DNA extraction, chromosome analysis and hormonal evaluations. RESULTS: Patients with normal sperm counts had a mean (sd) RI of 0.54 (0.05) and a mean testicular volume of 18.7 (5.2) mL, the respective values in those with pathological sperm counts were 0.68 (0.06) and 16.8 (6.0) mL, with a significantly greater RI in the latter (P < 0.001), but with no statistically significant difference in testicular volume between the groups (P > 0.05). CONCLUSION: These preliminary data suggest that an RI of >0.6 might be suggestive of a pathological sperm count in andrological patients. The intratesticular RI as measured by CDUS seems to be a reliable indicator for routine clinical use to identify subfertile men.

Plain abdominal radiography with transabdominal native tissue harmonic imaging ultrasonography vs unenhanced computed tomography in renal colic.

OBJECTIVE: To compare plain film kidney, ureter and bladder radiography (KUB) with transabdominal native tissue harmonic imaging ultrasonography (NTHI-US) vs unenhanced computed tomography (CT) for the diagnosis of urinary calculi in patients with acute flank pain. PATIENTS AND METHODS: In all, 112 patients who presented to the urological department with clinical suspicion of ureteric calculi were included. These patients had KUB with NTHI-US and unenhanced CT. Of the 112 patients, 14 were lost to follow-up and therefore excluded. For the remaining 98 patients (53 men, 45 women; mean age 43.3 years, range: 19-74) the KUB with NTHI-US findings were compared with the CT findings, which served as the 'gold standard'. RESULTS: In all, 75 patients were confirmed to have ureteric calculi. KUB with transabdominal NTHI-US detected 72 of the 75 patients with calculi (sensitivity 96%, specificity 91%, and accuracy 95%). Unenhanced CT detected urolithiasis in all 75 patients (sensitivity, specificity and accuracy of 100%). Both techniques showed further extra-urinary pathologies. CONCLUSION: This prospective study shows that CT is the most accurate technique for detecting urolithiasis. However, KUB with transabdominal NTHI-US is an alternative to unenhanced CT with comparable results.

Value of 3-dimensional transrectal/transvaginal sonography in diagnosis of distal ureteral calculi.

OBJECTIVE: In a prospective study, the feasibility of 3-dimensional (3D) transrectal/transvaginal sonography in comparison with transabdominal sonography and intravenous urography (IVU) in identifying distal ureteral calculi was evaluated. METHODS: Sixty-two patients in the urologic clinic with clinical suspicion of distal ureteral calculi were included. The patients consisted of 44 men and 18 women with a mean age +/- SD of 44 +/- 17 years. These patients underwent 3D transrectal/transvaginal sonography, transabdominal sonography with IVU, and, finally, ureterorenoscopy. RESULTS: Fifty-nine patients were confirmed to have distal ureteral calculi on the basis of urologic intervention (ureterorenoscopy). Three patients had a spontaneous stone passage immediately after imaging completion. The median size of the calculi was 3.7 +/- 2.00 mm. Transabdominal sonography detected 34 of the 62 patients with calculi (sensitivity, 55%). The median size of the calculi was calculated as 5.0 +/- 2.4 mm. The examination time was 6.5 +/- 2.7 minutes. Intravenous urography detected 44 of the 62 patients with ureterolithiasis (sensitivity, 71%). Herein, the median stone size was measured as 3.9 +/- 1.9 mm, and the examination time was 38 +/- 17 minutes. The combination of transabdominal sonography and IVU in visualization of ureterolithiasis raised the sensitivity to 81% (50 of 62 patients). Three-dimensional transrectal/transvaginal sonography showed ureterolithiasis in all 62 patients confirmed to have distal ureteral calculi (sensitivity and specificity, 100%). The median size of the calculi was calculated as 4.4 +/- 2.2 mm, and the examination took 1.9 +/- 0.6 minutes. CONCLUSIONS: The data in our prospective study show that transrectal/transvaginal sonography with 3D image assessment is superior to IVU and abdominal sonography for diagnosing distal ureteral calculi.