New scan aims to tell two types of hand arthritis apart

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Karnofsky index \> 70% * Obtaining written, signed and dated informed consent * Affiliation to a health insurance plan * For women of childbearing age (fertile, after menarche and until postmenopausal unless sterile after surgery) including on GnRH agonist for ovarian suppression: serum pregnancy test negative at baseline (within 7 days before injection of 99mTc-NTP 15-5). Menopause is defined as amenorrhea for at least 12 consecutive months with no other cause and FSH and oestradiol levels consistent with those of the post-menopausal period. * Ability and willingness to respect study visits, exams as well as protocol. RA Group: * certain diagnosis of rheumatoid arthritis less than 5 years old, according to the ACR/EULAR criteria, * symptomatic (finger pain \> 4 /10 on a numerical scale), * active synovitis (clinical and ultrasound), Group DOA: * certain diagnosis of symptomatic DOA less than 5 years old (finger pain \> 4 /10 on a numerical scale), * stopping NSAIDs for at least 8 days before the injection, Exclusion Criteria: * Ongoing use of non-steroidal anti-inflammatory drugs, * Treatment by local joint corticoid infiltration at the hand level in the month preceding the administration of 99mTc-NTP 15-5, * History of osteoarticular hand surgery. * History of hand soft tissue surgery in the past 6 months * Patients or patients 18 years old, * Pregnant or breastfeeding patient, * IMC\>30, * History of known allergy to excipients contained in the 99mTc-NTP 15-5 solution, * Persons deprived of their liberty, under guardianship/curatorship, or safeguarding of justice, * Inability to submit to the medical follow-up of the trial for geographical, family, social or psychological reasons. These conditions must be discussed with the patient before registration in the study. RA Group: * Use of biotherapies (anti-TNF alpha, rituximab, abatacept, anti-IL6 and anti-JAK) as background treatment. * Patients with a history of hand DOA