Correlation between clinical, histological, and ultrasound assessment of skin.
| Skin Thickness, mm | HFUS Parameters Echogenicity, Grayscale, Mean | SWE, kPa, Mean | mRSS | ||
|---|---|---|---|---|---|
| Local mRSS | Total mRSS | ||||
| SSc | |||||
| Clinical assessment (n = 53) | |||||
| Local mRSS | |||||
| Finger | +0.115 | +0.002 | +0.290* | – | – |
| Hand | +0.322* | –0.137 | +0.324* | – | – |
| Forearm | +0.410** | –0.232 (P = 0.094) | +0.236 (P = 0.088) | – | – |
| Abdomen | +0.243 (P = 0.079) | –0.084 | +0.055 | – | – |
| Total mRSSb | |||||
| Finger | –0.004 | +0.128 | +0.267 (P = 0.05) | – | – |
| Hand | +0.331* | –0.141 | +0.209 | – | – |
| Forearm | +0.357** | –0.337** | +0.154 | – | – |
| Abdomen | +0.148 | –0.163 | –0.059 | – | – |
| Histological parameters (n = 10) | |||||
| Forearm skin thickness | +0.483 | –0.444 | +0.321 | +0.506 | +0.407 |
| Forearm collagen | |||||
| Area | +0.669* | –0.098 | +0.717* | +0.650* | +0.497 |
| Mean intensity | +0.215 | –0.128 | +0.730 | +0.245 | +0.366 |
| Integrated densitya | +0.697* | –0.255 | +0.709* | +0.649* | +0.486 |
| Sum of grayscaleb | +0.697* | –0.255 | +0.709* | +0.649* | +0.486 |
| Overall cohort | |||||
| Histological parameters (n = 20) | |||||
| Forearm skin thickness | +0.417 (P = 0.067) | –0.571** | +0.229 | – | – |
| Forearm collagen | |||||
| Area | +0.697** | –0.064 | +0.307 | – | – |
| Mean intensity | +0.046 | –0.007 | +0.182 | – | – |
| Integrated densitya | +0.735** | –0.136 | +0.433 (P = 0.056) | – | – |
| Sum of grayscaleb | +0.735** | –0.136 | +0.433 (P = 0.056) | – | – |
↵aArea × mean intensity of collagen staining.
↵bSum total of staining intensity. Spearman rank correlation coefficient (ρ) is demonstrated between mRSS and ultrasound parameters at 4 regions of interest (finger, hand, forearm, abdomen) for SSc (n = 53) and with histological assessment at the forearm in a subgroup of SSc biopsy donors (n = 10). Correlation between histological assessment of forearm skin and ultrasound is also shown for combined healthy controls and SSc forearm skin donors (n = 20). Significance is illustrated by
↵*P < 0.05 and
↵**P ≤ 0.01. HFUS: high-frequency ultrasound; mRSS: modified Rodnan skin score; SSc: systemic sclerosis; SWE: shear wave elastography.