Automatic radiographic quantification of hand osteoarthritis; accuracy and sensitivity to change in joint space width in a phantom and cadaver study

Abstract

ObjectiveTo validate a newly developed quantification method that automatically detects and quantifies the joint space width (JSW) in hand radiographs. Repeatability, accuracy and sensitivity to changes in JSW were determined. The influence of joint location and joint shape on the measurements was tested.MethodsA mechanical micrometer set-up was developed to define and adjust the true JSW in an acrylic phantom joint and in human cadaver-derived phalangeal joints. Radiographic measurements of the JSW were compared to the true JSW. Repeatability, systematic error (accuracy) and sensitivity (defined as the smallest detectable difference (SDD)) were determined. The influence of joint position on the JSW measurement was assessed by varying the location of the acrylic phantom on the X-ray detector with respect to the X-ray beam and the influence of joint shape was determined by using morphologically different human cadaver joints.ResultsThe mean systematic error was 0.052 mm in the phantom joint and 0.210 mm in the cadaver experiment. In the phantom experiments, the repeatability was high (SDD = 0.028 mm), but differed slightly between joint locations (p = 0.046), and a change in JSW of 0.037 mm could be detected. Dependent of the joint shape in the cadaver hand, a change in JSW between 0.018 and 0.047 mm could be detected.ConclusionsThe automatic quantification method is sensitive to small changes in JSW. Considering the published data of JSW decline in the normal and osteoarthritic population, the first signs of OA progression with this method can be detected within 1 or 2 years.

OARSI Clinical Trials Recommendations: Hand imaging in clinical trials in osteoarthritis

“…Most clinical trials of rheumatoid arthritis (RA) have overcome this error by utilizing positioning frames with permanently embedded left-right markers designed in such a way as to make it impossible to image a hand with the wrong marker. As with knee radiography, changes in the position of the hand can change JSW values 8,9 and are likely to affect measurements of osteophytes. The use of a hand positioner is therefore recommended so that consistency is maintained both cross-sectionally and longitudinally.…”

“…There are no published reports that quantify the effect of radiographic technique (mA and kVp) on measurement error; however these factors are unlikely to alter measurements of JSW or osteophytes unless the quality is significantly compromised. Huetink et al 9 reported no systematic change in JSW as a function of the film-to-focus distance (FFD) for FFD covering 110e120 cm. Indeed as long as the hand is placed directly on top of the detector and the FFD is consistent at all time points for all patients, the magnification factor will change negligibly as a function of FFD.…”

“…Finckh et al 12 reported an average JSW change of 0.16 mm in RA subjects with a 4 year median follow-up time. In a phantom study Huetink et al 9 reported a smallest detectable distance of 0.028 mm for JSW measured using a "standard digital X-ray imaging system". Angwin et al 8 reported a value of 0.11 mm to represent a threshold for "an actual physical change in joint space width".…”

“…Most of the methods include software that puts a grid (mesh) over the hand x-rays and calculates the distance of joint space. More recently these methods have been evaluated on OA subjects to measure reliability 9 , correlation with semi-quantitative scoring 48 , and in a caseecontrol study, a comparison to clinical features 49 . With these techniques the software automatically delineates the opposing margins of the joint and calculates the JSW as the distance between the bone margins.…”

Identification of factors associated with the development of knee osteoarthritis in a young to middle-aged cohort of patients with knee complaints

“…During follow-up visit after 10 years standardized weight bearing posterior-anterior knee radiographs in a semiflexed position and lateral radiographs of the knee were made. Knee radiographs of the initially affected knee were scored for the presence and severity of OA using the 0-4 Kellgren and Lawrence (KL) scoring system [29]. Radiographic knee OA was considered to be present in patients with a KL score of 2 or higher.…”