The role of nuclear medicine in clinical practice
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The role of nuclear medicine in clinical practice

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The role of nuclear medicine in clinical practice The role of nuclear medicine in clinical practice Presentation Transcript

  • THE ROLE OF NUCLEAR MEDICINE IN CLINICAL PRACTICE Dr.Damayanthi Nanayakkara MBBS(SL), MPhil-Nucl.Med(UK) Senior Lecturer Nuclear Medicine Unit Faculty of Medicine
  • WHAT IS NUCLEAR MEDICINE?• Nuclear Medicine is a Medical specialty that uses• safe,• painless and• cost effective techniques• both to image the body and treat diseases
  • THE HISTORY OF NM• NM has a complex and multifaceted heritage• A land mark event of NM occurred in 1946 when a thyroid cancer patient treated with radioiodine caused complete cure• In 1970’s they start nuclear imaging• > 50 years , we are able to develop this up to Forensic NM
  • NUCLEAR MEDICINE IMAGING IS UNIQUE!• NM imaging documents the organ function in contrast to the radiological imaging which shows mainly the anatomy• NM imaging allows us to identify abnormalities in very early stage• Early treatment and successful follow up
  • DIFFERENCE BETWEEN RADIOLOGY AND NUCLEAR MEDICINENuclear Medicine RadiologyIonizing radiation X-rayWhole body irradiation Interested areaNo accumulation AccumulationOrgan function AnatomyLess radiation Radiation ++
  • HOW SAFE RADIATION IS?• Among the diagnostic imaging procedures, NM is the safest diagnostic method• A patient receive an extremely small amount of a radio pharmaceutical just enough to get sufficient information
  • RULES AND REGULATIONS –IONIZING RADIATION• ICRP – International Commission of Radiation Protection• Local rules and regulations by a parliamentary act• To protect unnecessary radiation to the patients, relatives and the general public• To protect the staff
  • LEGISLATIONS• Regulations establish the basic safety standard for the protection of workers, general public including patients against the risk of ionizing radiation• 3 principles1.No practice shall be adopted unless its introduction produces a net benefit2.The ALARA principle3.The equivalent dose to individuals shall not exceed the limits recommended for the appropriate events by ICRP
  • CORE KNOWLEDGE OF RADIATION PROTECTION• Nature of ionizing radiation and its interaction with tissues• Genetic and somatic effects• Basic safety standards (time, distance and shielding)• Quality assurance and QC applied to both equipments and techniques• Appropriate training, certificates(licenses) and guidelines
  • UNNECESSARY DOSE TO A PATIENT• Clinically unhelpful investigation (it has been estimated that approximately 20% of radiological examinations requests are inappropriate & unnecessary and 30% of investigations are unnecessary repeats because the previous study has been lost )• Unnecessary large patient dose• All doctors are responsible for minimize the patient dose
  • GUIDELINES FOR DOCTORS• A useful investigation which gives the results positive / negative will alter management/ add confidence to the physician’s diagnosis• Prevent • Unnecessary waiting list • Delay in initiating treatment • Waste of limited resources • low standards • Unnecessary radiation
  • DOCTOR’S DILEMMA(MEDICAL DECISION MAKING)• May be a rule of thumb for detecting whether a test should be done or not, could depend on the following dialogue between a patient and a doctor“What will you do if the test is negative?”“Nothing is indicated then”“What will you do if the test is positive?”“Nothing again , because nothing is possible.”“Why do you want to investigate, then?”Late Dr.R.D.Ganatra, former Head/IAEAWJNM Jan 2003
  • NM APPLICATIONS• As an integral part of patient care NM is used in thea) Diagnosis (invitro/ invivo)b) Treatmentc) Preventiond) Follow upe) Research
  • NUCLEAR MEDICINENM application in medical practice• Non imaging• Imaging• Treatment(therapy)
  • NON IMAGING• Radioimmuno assay(RIA/IRMA)1.Thyroid function tests (TT4,TT3,FT4 & TSH)2.Sex hormones (FSH/LH/Oerstrogen/Progestrogen & testosteron)3.Pituitary hormones TSH/ Prolactin/FSH/LH4.Steroids Cortisole• Uptake studies (radioiodine 131)• GFR• Red cell mass• C14-urea breath test for H. pylori
  • NEONATAL SCREENING(CH, G6PD,CAH, PKU, GALCTOSEMIA) • Congenital hypothyroidism is the commonest cause for MR • If detected before 2-3 months and treated adequately – can prevent MR/ adequate growth and normal life • Awareness, early detection and education to parents , primary health care workers are very important
  • IMAGING• Using very small amount of radioisotope(radiopharmaceutical)• IV or oral adminstration• Nearly one hundred different NM imaging procedures are available• Almost all organs and systems in the body could be imaged
  • REQUIREMENTS• Gamma camera(planer/SPECT)/PET• NM computer system with compatible soft wares• Radioisotpe (Tc99m, I131, I123,Re 188,Y 90, P32 )• Radiophramaceutical(DMSA,DTPA, MDP,Mebrofenin,sestamibi,MIBG etc)• Radiation measuring devises(Caliberators)• Radiation monitoring devises(suervey metres, TLDs)• Trained staff
  • NUCLEAR ENDOCRINOLOGY• Thyroid Tc99m IVPeadeatrics: agenesis/ ectopic/lingual/TG cystsAdult: type of goiter(MNG/SN/DE/Retrosternal ext, cold nodules)Etiology of TT; TNMG/GD/STN/thyroiditis• Parathyroid Tc99m/ I131, sestamibi., tetrophosmine etc• Neuroendocrine, Adrenal –MIBG• Breast . Scintimammography and sentinal node detection
  • NUCLEAR ENDOCRINOLOGY• Thyroid cancer – 100% cure if treated early and adequately• Papillary/ follicular ca• TT/NTT (TG/TSH after 6/52)• I131 3 mci dose orally, 48h later WB scan for a)residual assessment b)metastases• If negative ---------- thyroxin till suppressed TSH• Residual --------- ablation with radioiodine• Metastases ablative (high dose) therapy• Regular follow up
  • BONE• Malignancies• Infections• Fractures• Avascular necrosis• Mandibular condylar hyperplasia• Child abuse
  • GASTRO-ENTEROLOGY• Meckel’s diverticulum• Chrons/ulcerative collitis• Colonic ca• Liver/spleen• hepatobiliary• GI bleeding
  • LYMPHATIC SYSTEM• Lymphoscintigraphy• Sentinal nodes ; Melanoma/ ca bresat
  • NUCLEAR CARDIOLOGY• Cardiac perfusion before angio catheterisation and dilatation• Cardiac function (ejection fraction)
  • LUNG SCINTIGRAPHY• Simple non invasive method for detecting pulmonary embolism• V/Q scan or ventilation/perfusion scan
  • NUCLEAR NEUROLOGY• Brain ischemia• Brain atrophy
  • NM IN NEPHROLOGY• NM is widely applied in nephrology• Assess renal function accuratelyThere are 2 main studies Imaging(scintigraphy) Functional (DF, GFR)• DMSA(dimercapto succinic acid) renal cortical agent – scaring, cong. Abnormalities, DF• DTPA(diehtylene triamine pentaacetic acid) renal tubular agent – obstruction, renal function, may be reflux , renal transplant etc• Captopril studies- reno vascular disease
  • COMMON RENAL PROBLEMSUrinary tract infection (upper/lower)• Acute pyelonephritis (APN)• Visico-ureteric reflux (VU reflux)• Pelvi-utreteric junction obstruction (PUJO)• Posterior urethral valve (PUV)• Chronic renal failure (CRF)/nonfunction• Renovascular hypertension (RVH)• Renal transplant
  • TYPES OF RENAL ISOTOPE STUDIES• Tc99m labeled DMSA / GHA• Tc99m labeled DTPA / MAG3• Tc99m labeled DTPA / Diuretic augmented• Tc99m labeled DTPA / captopril augmented• Tc99m pertechnetate perfusion
  • TC99M LABELED DMSA• Di-Mercapto-Succinic Acid• Renal cortical imaging agent• Binds to renal parenchymal cells and accumulate in the functional renal cortex• IV administration(2-3 mCi)• Delayed imaging(static)2-3h post injection• Well hydration/ pre void• Prone image (sedation sos)• Static imaging
  • INDICATIONS TO PERFORM A DMSA SCAN1. Diagnosis of acute pyelonephritis (APN) in children- highly sensitive2. Detection renal cortical scaring3. Detection of cong. abnormalities absent kidney dysplastic/ small kidney duplex kidney horseshoe kidney ectopic/ mal-position
  • INTERPRETATION• Generally round shaped, equal in size , position• Homogeneous tracer distribution• Variations- upper pole appearance -shape (triangular, fetal lobulaion, multicystic)• Focal defects, multifocal defects, diffusely decreased activity
  • NORMAL DMSA
  • DMSA• Highly sensitive and reliable technique for the diagnosis of renal parenchymal infection• Gold standard for the diagnosis of APN• Recommended after 6/12 of proven UTI of less than 7 years
  • TC99M LABELED DTPA• Diethylene Triamine-Penta acetic-Acid• Renal tubular agent• Not absorbed/ secreted by tubular cells• IV administration(2-5 mCi)• Dynamic imaging for 20 min• Well hydration/ prevoid• Prone image (sedation sos)
  • INDICATIONS TO PERFORM A DTPA SCAN1. Outflow tract obstruction(PUJO)-Diuretics2. Reflux- indirect/direct MCUG3. Assessment of renal function/ DF4. Pre/ post transplant evaluation(anterior imaging)5. Renal Donor evaluation6. Renal perfusion7. Renovascular hypertension(RVH)-captopril8. Neonatal hydronephrosis
  • NORMAL DTPA SCAN/ RENOGRAM• Perfusion – kidneys should be visualized within 5-6 sec• Maximum activity is seen at 3-5 min and then the bladder (renogram)• Time/activity curve (ROI/BG) for 20min• Normal renogram -3 phases • Perfusion/vascular • Cortical extraction • Excretory
  • INTERPRETATION- DTPA• Visual analysis of the renogram • Perfusion • Uptake, size , position and the shape • Diuretic response• T/A curves • Perfusion, elimination and excretion • Shape • Tmax• Differential function (DF 40-50% normal)
  • OUTFLOW TRACT OBSTRUCTION (PUJO)• Obstruction is suspected on US.scan• Reduced renal perfusion• Gradual up sloping curve• No excretion• Long standing, no perfusion/excretion, flat• Differentiate obstruction/ dilatation with IV furosemide
  • RENAL ARTERY STENOSIS• Young hypertensive pt• Small kidney• Deteriorate renal function with ACE inhibitors• Doppler evidence• ? Functionally significant stenosis
  • CAPTOPRIL RENOGRAM• Test is highly specific for RAS• >60% narrowing• Decrease afferent arteriolar pressure• Stimulate renin by juxta GM apparatus• Renin – angiotensin 1• By Angiotensin converting enzyme(ACE) into angiotensin 11• Angiotensin 11- on efferent arteriole to increase BP to maintain GFR• CAPTORIL prevent this normal mechanism• Impaired
  • CAPTOPRIL RENOGRAMPositive scan – high probability of RVHNot suitable for screening(low prevalence of RAS )• Patient selection/ preparation is a must• Withhold capto-48h, 7 days lisinipril,enalapril• Cont. all other medication• Fasting/ well hydrated• 25-50 mg captopril orally• 1h post capto- 5-6 mCi of Tc99m-DTPA bolus• BP monitoring, IV line , emergency –hypotension/ARF• One day/ two day protocols
  • CAPTOPRIL RENOGRAM• Normal captopril study – very low probability of functionally significant RAS• Abnormal – high probability of functionally significant RAS• Need base line renogram for comparison• sensitivity/specificity is >90%(with good prep/selction)• Delay in perfusion• Reduced uptake• Prolong parenchymal transit time/ delay in time to peak (>5min compared with the baseline)• Poor excretion• Bilateral RAS , uncommon and difficult• <60% RAS may not be demonstrated
  • RENAL TRANSPLANT EVALUATION• Well established pre/ post transplant assessment using NM studies• Transplant is placed in the ant.iliac fossa(imaging anteriorly/supine)• Baseline study shortly after surgery• Radioisotope bolus- perfusion • Exactly with the iliac vessels • Parenchymal phase-3-5 min • Excretion within 5 min
  • RENAL TRANSPLANT EVALUATION• Complications• - hyper acute rejection- no perfusion (immediate after)• ATN – preserved perfusion, cortical retention and impaired excretion (first 3-4 days, resolve within few weeks)• acute rejection- decrease perfusion, uptake and excretion (first 2-3 months)• Cyclosporin toxicity- similar to ATN, several weeks after ATN, good perfusion, poor function, improve after withdrawal of drugs• Surgical- urinoma, obstruction• Renal vain thrombosis (no venous collaterals, similar to arterial obstruction, no perfusion -Photopenic defect)
  • THERAPEUTIC NMI131• therapy/ ablation• Benign thyroid diseases TT/ large MNG• Malignant thyroid diseases- Ca thyroid/ metasatasesSolid Y90 -radio-synevectomy active Rh ArthritisP32 – Polycythemia Rubra VeraSr89 –Palliative bone therapyRe 188- Lipiodol for Liver cancer
  • SINGLE PHOTONE EMISSION CT(SPECT)
  • POSITRON EMISSIONTOMOGRPAHY(PET)-DUAL PHOTON
  • NORMAL THYROID SCAN•Uniformly distributedtracer.•No labeling defectsseen.
  • HYPOFUNCTIONING NODULE•Focal labeling defect•“cold area”
  • LINGUAL THYROID
  • PARATHYROID –TC99M SESTAMIBI adenoma
  • NUCLEAR MEDICINEIs the science which apply atomic energy in a peaceful manner for the benefit of the human beingIt is not unclear Medicine
  • THANK YOU!