This study is a phase Ii clinical trial aimed to evaluate the performance of 99mTc-NTP 15-5 to identify a pathological hand joint in each group ; digital osteoarthrosis and rheumatoid arthritis

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