A set of high-quality US images of synovitis of wrist, PIP, knees and MTP joints from patients with RA was evaluated using images from the same register and applying the same approach as described in step 1.
After the exercise on static images, the experts performed bilateral US scanning of the wrist, PIP,2–5 (link) knee and MTP1–5 (link) joints in six different patients twice in two rounds over 2 days (first day wrist and PIP joints, second day knee and MTP joints), using predefined joint positions as follows:

Wrist joints (ie, radiocarpal and midcarpal joints were evaluated as a single site): palms facing down and wrist positioned flat on the examining table, as neutral as possible but relaxed; shoulder and elbow relaxed; elbow rested on the table. Scanning at the level of the radio-lunate joint.

PIP joints: palms facing down and wrist positioned flat on the examining table, as neutral as possible but relaxed, scanning on the dorsal midline aspect.

Knee joints (ie, suprapatellar and parapatellar recesses were scored as a single site): knee 30° flexed and scanning on suprapatellar midline for the suprapatellar recess; knee extended and scanning the parapatellar areas using the retinacula as a landmark for the parapatellar medial and lateral recesses. Doppler signal was recorded only in the medial and lateral parapatellar recesses.

MTP joints: foot placed resting (with knee 30° flexed) over its plantar aspect. Scanning recorded on the dorsal midline aspect.

For all examinations, identical ESAOTE Technos MPX (Genoa, Italy) US machines with an 8–14 MHz linear array transducer were used with identical PD settings (frequency of 10.1 MHz, pulse repetition frequency of 750 Hz and Doppler gain of 50–53 dB). Each patient was assigned to one machine and the sonographers then rotated from one machine to the next in a predefined sequence with 10 min allocated for scanning and recording the findings on a standard score sheet. Participants were blinded to the patients’ clinical details (ie, presence or not of active disease).17