Strain wave elastography for evaluation of renal parenchyma in chronic kidney disease.

OBJECTIVE: Chronic kidney disease (CKD) is an important and costly health problem in developed countries and has a tendency to progress to end-stage renal disease regardless of the aetiology. This progress ends in interstitial fibrosis, which decreases the elasticity of tissue. Elastography is a developing technique to assess tissue elasticity. The aim of this study was to determine the difference of strain index (SI) value of renal parenchyma between patients with CKD and healthy individuals. In addition, SI differences of inter-stages were studied. METHODS: Toshiba (Toshiba Medical Systems Corporation, Otawara, Japan) Aplio™ 500 ultrasound device and 3.5- to 5.0-MHz convex probe were used for the elastography examinations. RESULTS: A total of 58 patients with CKD from nephrology and endocrinology clinics (30 males and 28 females; mean age, 56.14 ± 11.60 years) and 40 normal healthy individuals (19 males and 21 females; mean age, 51.70 ± 11.71 years) were included in this prospective study. The mean SI of normal healthy individuals and patients with CKD (regardless of stages) was 0.42 ± 0.30 and 1.81 ± 0.88, respectively (p < 0.001). SI values were not statistically significant among the CKD stages (except CKD Stages 1 and 3). The area under the receiver operating characteristic curve was 0.956 for SI. The optimal cut-off value for the prediction of CKD was 0.935 (sensitivity, 88% and specificity, 95%). CONCLUSION: SI value of sonoelastography can be used to differentiate patients with CKD and healthy individuals. Sonoelastography is an acceptable technique to approach patients with CKD, but we have not shown that it can reliably differentiate different stages. ADVANCES IN KNOWLEDGE: Determining a cut-off SI value between normal and diseased renal parenchyma can help in the diagnosis of CKD.

The value of real-time ultrasound elastography in chronic autoimmune thyroiditis.

OBJECTIVE: Chronic autoimmune thyroiditis (CAT) (chronic lymphocytic thyroiditis-Hashimoto's thyroiditis), which is the most common inflammatory disorder of the thyroid gland, causes hypothyroidism. Ultrasound elastography is a newly developed sonographic technique that provides an estimation of tissue elasticity by measuring the degree of tissue displacement under the application of an external force. In this study, our aim was to evaluate the accuracy of strain index ratio with real-time ultrasound elastography and to calculate the cut-off point for the diagnosis of CAT. Our aim was also to lead further studies on other pathological changes such as lymphoma, malign nodules etc. based on CAT by using this cut-off point. The gains from this study and further studies will assist clinical diagnoses and follow-up. METHODS: Aplio™ 500 ultrasound machine (Toshiba Medical Systems Co. Ltd, Otawara, Japan) with linear 4.8-11.0 MHz transducers and elastography software was used. Routine B-mode (dimensions and parenchymal echogenicity) ultrasound evaluation was performed prior to the ultrasound elastography. RESULTS: A total of 31 randomized patients (3 males, 28 females) with a mean age of 39.13 ± 10.16 years (range, 16-58 years) with CAT and 21 healthy controls (6 males, 15 females) with mean age of 34.67 ± 16.31 years (range, 14-81 years) were prospectively examined. The mean values of thyroid-stimulating hormone (TSH; normal TSH value is 0.27-4.20 IU ml(-1)) and anti-thyroid peroxidase (anti-TPO; normal anti-TPO value is 0-34 IU ml(-1)) were 3.40 ± 2.70 and 373.66 ± 148.94 IU ml(-1), respectively. No correlation was detected between serum TSH and thyroid tissue strain index (Spearman r coefficient of TSH was -0.290). Positive-sided correlation was detected between anti-TPO values and thyroid tissue strain index ratio (Spearman r coefficient of anti-TPO was 0.682). The median strain index ratio of patients with CAT (1.39 ± 0.72) was significantly higher than the mean ratio of the controls (0.76 ± 0.55). The area under the receiver operating characteristic curve was 0.775 (95% confidence interval). The optimal cut-off value (in which the sum of sensitivity and specificity was highest) for the prediction of diffuse thyroid pathology was 0.677. For this cut-off ratio, thyroid stiffness had 96% sensitivity and 67% specificity. A total of 30 of 31 patients (96%) and a total of 7 of 21 healthy controls (33%) exceeded the cut-off points. CONCLUSION: The strain index ratio was higher in CAT than in normal thyroid parenchyma in real-time ultrasound elastography. Thus, it seems to be a useful method for the assessment of CAT with real-time ultrasound elastography, and further studies assessing the correlation of sonoelastography findings and histopathological subtypes of CAT would enrich the findings of the present study. ADVANCES IN KNOWLEDGE: In our study, we detected the stiffness ratio of the thyroid tissue in patients with CAT. The cut-off value should be helpful for diagnosis or follow-up of the recently developed lesions such as lymphoma, malign nodule, etc. based on CAT. This study should also encourage new studies about CAT and ultrasound elastography.