Radionuclide imaging in patients with fever

Otto Lang MDDept Nucl Med

3rd School of MedicineCharles University

Prague

materials for medical students

Fever

• Non-specific reaction of the body (T>38oC)

• Most frequent cause inflammation (tumors)

• Inflammation – Infective and non-infective

• Usually fever with other signs of imflammation

• Clinical picture very important

• Other laboratory tests including imaging methods (NM, sono, CT, MRI) are essential

Fever • Probable etiology should be taken into account

– Fever in patient post surgery

– Fever in patient with renal failure

– Fever in patient with HIV positivity

– Fever in patient with septicaemia

– Fever of unknown origin• Fever for 3 weeks with unknown origin despite 1 week intensive hospital

evaluation

– Fever in children

– Fever in soft tissue inflammation

– Fever in bone infection

– Fever in patient with abdominal sepsis

– Fever in patient with different tumors

Fever • Radiopharmaceuticals

– organ specific – show damage of appropriate organ (defect of functioning tissue)

• Tc-99m diphosphonates – bone scan

• Tc-99m DMSA - kidneys

– organ non-specific – accumulates directly in inflammed tissue (little bit tumors, wounds, hematomas)

• Ga-67 citrate – infective, non-infective, tumors

• labeled leukocytes – pyogenic infection

• Tc-99m IgG – non-infective

• F-18 FDG

Ga-67 - properties• Used in a form of citrate• Binds to plasmatic proteins, excretion by

kidneys (24 h) and then intestinal mucosa• Degree of accumulation correlates with

process activity• Basic principles of accumulation:

– Complexes with plasma transferrin– Binds to intracellular lactoferrin inside leukocytes– Can binds directly to some parts of bacteria

• Patient preparation:– Laxatives - fast elimination from the bowel

Ga-67 - procedure

• Injection of 150-180 MBq – high energy, long half-life, high absorbed

dose, worse spatial resolution (image qual)

• Acquisition 4-6 h p.i., then from 24 h to 3-4 days

• Collimator for medium energy

• Whole-body study, spot view (larger frame matrix), SPECT

Ga-67 – clinical significance

• High sensitivity (90%) but low specificity –

used as a locating agent – it locates site of damage so other more specific methods can be used

• More suitable for chronic inflammation

• Not very good for abdominal inflammation evaluation due to physiological excretion via intestinal mucosa

Ga-67 – clinical indications

• Specific inflammation (sarcoidosis, tuberculosis)

• Imunocompromised patients (lung inf)

• Thoracic inflammation (fibrosis, vasculitis)

• Non-infective inflam – process activity (kollagenosis)

• Fever of unknown origin– wide spectrum of possible causes

• Osteomyelitis

• Abdominal and retroperitoneal inflamation (pyelonefritis, absces)

Labeled leucocytesproperties

• Basic pinciples of accumulation– positive chemotaxis (no injury during

labeling process)– also healing wounds and tumors

• Labeling process– in vitro - separation, laboured– in vivo - monoclonal antibodies

• Patient preparation– fasted (blood processing)

Labeled leucocytes procedure

• Labeling – 60 ml venous blood (kids min. 12 ml) – separation, washing up, labeling – cca 1.5 h– Labeling with Tc-99m HMPAO (300 – 500 MBq)

or In-111 oxin (20-40 MBq)

• Data acquisition – 30 min, 4-6, 24 (48 In) h post injection– Whole-body study, spot view (larger frame

matrix), SPECT

Labeled leucocytes clinical indication

• Unspecific bowel disease (Crohn, UC)

• Diabetic foot syndroma

• Musculosceletal infection

• Fever of unknown origin (within 2-3 w)

• Imunocompromised patients

• Joint prosthesis infection

• Acute arthritis

• Vascular prosthesis infection

Tc-99m IgG

• Non-specific polyclonal

• Labeled with In-111 or Tc-99m.

• Accumulates predominantly within interstitial space

• Physiological accumulation – blood-pool, liver, spleen, kindeys, bone marrow and nasal mucosa

• Main indication

– Revmatic (non-infective) inflamation

F-18 FDG• Metabolic analog of glucose

– enter cells but no metabolism – accumulates according to degree of metabolic turnover

• Imaging by PET

• Metabolically active processes (inflam, tumors) - more glucose than other tissue

• Mainly used as a locating agent (like Ga-67) and mark of activity

• PET – much better spatial resolution (better image quality)

New ways

• Imaging of bacteria– labeled chemotherapeuticals (chinolony)

• dependent on antibiotics therapy

• Chemotactic peptides– interleukin 2 – non-infective inflammation

(autoimmune)

• Combined methods– Streptavidin (tissue senzibilization) and then

labeled biotin

Ga-67 citrate

physiological distribution

male and female

Ga-67 - sarkoidosis

Ga-67 – sarkoidosispanda-sign

Ga-67 – sarkoidosispanda and delta sign

Ga-67 – lung fibrosis

Ga-67 - tuberculosis

Ga-67 - urosepticaemia

Ga-67 – thyroiditiscomparison with Tc-99m pertechnetate

Labeled leucocytes

physiological distribution

Labeled leucocytes ulcerative colitis

Labeled leucocytes ulcerative colitis or Crohn´s disease?

Labeled leucocytes ulcerative colitis

Labeled leucocytes infection of hip prosthesis

Diabetic foot syndroma

Patient JU 1961, X-ray chron. OM

Patient JU 1961, bone scan posit.

Patient JU 1961, leu scan negative

F-18 FDGphysiological distribution

FUO

Fever of unknown origin(all methods failed)PET revealed:- aortitis/vasculitisAs a bonus:- Breast cancer(vasculitis as a paraneoplastic sign)

Vascular prosthesis infection PET FDG

Joint prosthesis infectionPET FDG