Functional Imaging of Digital Osteoarthritis and Rheumatoid Arthritis Using 99mTc-NTP 15-5 in Nuclear Medicine

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