ROLE OF 18F-FDG PET-CT IN ASSESSING TREATMENT RESPONSE TO DISEASE MODIFYING ANTI RHEUMATOID DRUGS (DMARDs) IN RHEUMATOID ARTHRITIS.

Dr. SANTOSH NANDIGAM, RADIATION MEDICINE CENTER, TATA MEMORIAL HOSPITAL , MUMBAI

MANIFESTATIONS OF RHEUMATOID ARTHRITIS

ARTICULAR EXTRA ARTICULAR 1)LARGE JOINTS 1)SUBCUTANEOUS NODULES 2)SMALL JOINTS 2)NEUROLOGICAL COMPRESSION 3)PULMONARY : NODULES, EFFUSION, 4)CARDIAC: MYOCARDITIS 5)LYMPHADENOPATHY, 6)SPLENOMEGALY AND MANY OTHERS ORGAN INVOLVEMENT

**TREATMENT: DMARDS**

EVALUATION OF TREATMENT RESPONSE

1) CLINICAL – Joint pains, swelling, rise of temperature, morning stiffness.

2) SEROLOGY - RA factor, ESR, CRP, anti CCP antibodies.

3) SYNOVIAL JOINT FLUID EXAMINATION- Volume, Color, WBC, Polymorphs, Culture, Glucose.

4) EULAR SCORE – Joint distribution(0-5), clinical symptoms(0-1), serology (0-3), acute phase reactants(0-1).

*Total > or = 6 Definite RA*

5) X RAY 6) MRI

ROLE OF FDG PETCT IN RA:

1) DIAGNOSING THE INFLAMMATION IN JOINTS.

2) QUANTIFICATION OF INFLAMMATION IN JOINTS. QUANTITIVE PARAMETERS IN PET CT: 1)SUVmax-STANDARD UPTAKE VALUE maximum. The SUV is the ratio of the image derived radioactivity concentration to the injected radioactivity. 2)MVP-METABOLIC VOLUMETRIC PRODUCT (NEW PARAMETER). The sum total of individual products of SUVmax & ROI volume. 3) COMPARISON OF POST TREATMENT SCAN FINDINGS WITH BASELINE SCAN FOR ASSESSING TREATMENT RESPONSE(GOOD, MIXED, NO RESPONSE).

4) DIAGNOSIS OF EXTRAARTICULAR LESIONS (LYPMHATIC, PULMONARY Etc).

IMPORTANCE OF PETCT in RA:

1) Assessing the baseline (pretreatment) inflammation in the joints involved.

2) After starting DMARDS, assessing the inflammation response( reduction / no response) at 3 months.

GOOD RESPONSE MIXED RESPONSE NO RESPONSE

3) Continuation of same DMARDS if response is good, change or add other DMARDS if response is mixed or poor.

4) Assess the inflammation again after 3 months with PETCT and assess the overall response .

ROLE OF 18F-FDG –PET CT TIME OF FLIGHT SCAN IN RA

GOOD RESPONSE

MIXED RESPONSE

NO RESPONSE

CORRELATION ANALYSES:

CLINICAL SYMPTOMS / JOINTS INVOLVED.

INDIVIDUAL TOTAL EULAR SUVmax and MVP SEROLOGY SCORE. product on PETCT scan. PARAMETERS. THESE PARAMETERS WERE EVALUATED PRETREATMENT, 3 MONTHS POST TREATMENT AND 6 MONTHS POST TREATMENT.

PERCENTAGE CHANGE IN THESE PARAMETERS at 3RD MONTH & 6TH MONTH POST TREATMENT WERE COMPARED TO BASELINE (PRETREATMENT).

Analysis made in the following aspects:

1. The concordance with clinical symptomatic response and MVP response evaluation observed in the PETCT scan. (The decrease or increase in the MVP observed is correlating with the decrease or increase in the symptoms and thus the clinical response respectively.

2. The discordance with EULAR score, individual serological parameters to clinical response. The EULAR score components in the inverse relation with the clinical symptoms.

3. The significance of assessing the MVP along with SUV in the management with DMARDS, (response evaluation, change of treatment, adding extra drug, dose etc-Step up therapy)

ADVANTAGES:1) Easy diagnosis.2)Quantification.3)Early intervention and treatment modification.

LIMITATIONS:1) Cost. 2) Radiation.