The reproducibility of shear wave and strain elastography in epidermal cysts

Purpose@#This study evaluated epidermal cyst elasticity using multiple parameters of strain elastography (SE) and shear wave elastography (SWE) and assessed the reproducibility of each parameter. @*Methods@#This retrospective study included 73 patients with epidermal cysts who underwent SE and SWE. SE scores were classified as 1-4 according to elasticity. The strain ratio was evaluated using the elasticity ratio of lesions and adjacent subcutaneous fat tissue. For SWE, the shear wave velocity (m/s), elasticity (kPa) according to the Young modulus, velocity ratio, and elasticity ratio were evaluated. All values were measured twice. The reproducibility of SE and SWE measurements was assessed. The relationships among SE and SWE measurements were evaluated. @*Results@#The strain ratio on SE images showed good reproducibility (intra-class correlation coefficient [ICC]=0.789), and SE scores showed substantial reproducibility (kappa=0.753 and kappa=0.758 for readers 1 and 2, respectively). Moderate reproducibility was found for shear wave velocity and elasticity (ICC=0.750 and ICC=0.648, respectively), as well as for the shear wave velocity of the reference tissue and velocity ratio (ICC=0.747 and ICC=0.713, respectively). All SE scores were positively correlated with the strain ratio (P<0.001). The strain ratio in the second SE session was significantly correlated with the elasticity ratio and velocity ratio in the first SWE session (r=0.245, P=0.037; r=0.243, P=0.038, respectively). Other variables were not correlated. @*Conclusion@#SE and SWE parameters of epidermal cysts showed moderate to good reproducibility. The strain ratio on SE showed good reproducibility and could provide relatively objective and consistent measurements of epidermal cyst elasticity.

Inter- and Intra-Observer Variability of the Volume of Cervical Ossification of the Posterior Longitudinal Ligament Using Medical Image Processing Software

OBJECTIVE: Computed tomography (CT)-based method of three dimensional (3D) analysis (MIMICS®, Materialise, Leuven, Belgium) is reported as very useful software for evaluation of OPLL, but its reliability and reproducibility are obscure. This study was conducted to evaluate the accuracy of MIMICS® system, and inter- and intra-observer reliability in the measurement of OPLL. METHODS: Three neurosurgeons independently analyzed the randomly selected 10 OPLL cases with medical image processing software (MIMICS®) which create 3D model with Digital Imaging and Communication in Medicine (DICOM) data from CT images after brief explanation was given to examiners before the image construction steps. To assess the reliability of inter- and intra-examiner intraclass correlation coefficient (ICC), 3 examiners measured 4 parameters (volume, length, width, and length) in 10 cases 2 times with 1-week interval. RESULTS: The inter-examiner ICCs among 3 examiners were 0.996 (95% confidence interval [CI], 0.987–0.999) for volume measurement, 0.973 (95% CI, 0.907–0.978) for thickness, 0.969 (95% CI, 0.895–0.993) for width, and 0.995 (95% CI, 0.983–0.999) for length. The intra-examiner ICCs were 0.994 (range, 0.991–0.996) for volume, 0.996 (range, 0.944–0.998) for length, 0.930 (range, 0.873–0.947) for width, and 0.987 (range, 0.985–0.995) for length. CONCLUSION: The medical image processing software (MIMICS®) provided detailed quantification OPLL volume with minimal error of inter- and intra-observer reliability in the measurement of OPLL.

Treatment of Polyostotic Fibrous Dysplasia of the Thoracic Spine with Intravenous Pamidronate: Result from 9 Months Follow Up

Fibrous dysplasia of the spine is very rarely observed. We reported a case of a 57-year-old woman, who presented with neck and bilateral shoulder pain with histologically confirmed fibrous dysplasia, involving the first and second thoracic vertebrae. Clinical and radiological findings were not specific for fibrous dysplasia. The histological biopsy was required for a confirmed diagnosis. Endocrine and metabolic evaluations are required to rule out diseases such as hyperthyroidism, Cushing syndrome and osteomalacia. Fibrous dyplasia can be managed by appropriate medical and surgical treatments based on the patient's neurological status and symptoms. Our patient was given intravenous pamidronate 60mg/day for 3 days. After 9 months, her initial symptoms were improved, but computed tomography scan of the thoracic spine showed no change of the lesions.