NUCLEAR MEDICINE:OVERVIEW

Jiraporn Sriprapaporn, M.D.Division of Nuclear Medicine

Department of RadiologySiriraj Hospital

Thyroid ScanThyroid Scan

Technique:Prep: No T4 at least 2 wksTc-99m iv. or I-131 orallyStatic imaging at 20 min or 24 hr respectively

Indications:Solitary thyroid nodule or MNG with dominant nodule (suspected CA)Congenital hypothyroid, R/O ectopic thyroidSubsternal goiter (I-131)Hyperthyroidism with single thyroid nodule; R/O toxic adenomaEvaluate thyroid remnant post thyroid surgery

Thyroid ScanThyroid Scan:: TechniquesTechniques

Tc-99m thyroid scanFor routine use !!2 mCi TcO4

- IV injectedImaging at 20 mins later

I-131 thyroid scanFor special purposes60-100 uCi I-131 is orally givenImaging at 24 hr.later

Withdraw T4 at least 2 wks before thyroid scan

Trapping Trapping + Organification

Thyroid ScanThyroid Scan

S

II--131131 TotalTotal--body Scan body Scan ((TTBSBS):):TechniquesTechniques

Patient preparation: Withdraw thyroid H (T4) 4-6wks prior to TBS, TSH > 30 mIU/LDiagnostic dose of I-131: 2-5 mCi orally givenAnterior and posterior whole-body imaging at 72hrs laterTBS can also performed after 3-7 d of RAI Rx dose

II--131 Total131 Total--body Scanbody Scan

Thyroid

Bladder

T

B

C

Lung metas.

Bone ScanBone Scan:: IndicationsIndications

Cancer patients: Bone scan is an extremely sensitive and cost effective modality for

staging Evaluate patients with bone pain, increased alkaline phosphate, or hypercalcemia to rule out osseous metastasis.

Infection: DDx cellulitis & osteomyelitisReflex sympathetic dystrophy (RSD)

Bone ScanBone Scan

R’pharm: Tc-99m MDP 20 mCi iv.Good hydration pi.Technique

Whole-body: at 3 hr pi.3-phase: Vascular, soft tissue, skeletal phases

Uptake // flow & osteoblastic activityNature: nonspecific Advantages: sensitive > X-ray, evaluate entire skeleton

Bone ScanBone Scan--Related TermsRelated Terms

3-phase bone scanSuperScanFlare phenomenonStress fractureOccult fracture

NormalNormal Bone ScanBone Scan

BONE METASTASESBONE METASTASES

Vascular phase

Soft-tissue

delayed 3-hr

33--PPhasehase BBoneone SScancan--AOMAOM

OSTEOSARCOMAOSTEOSARCOMA

Phase I : Vascular phasePhase II : Soft tissue phasePhase III : Bone phase

Brain Perfusion Study Brain Perfusion Study ((SPECTSPECT))

Tracer: Tc-99m neurolite (ECD)Dose: 20-25 mCi IV.Indications:

StrokeDementiaSeizure

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Normal Brain SNormal Brain SPECTPECT

Stroke at left temporoparietal region

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3D

BBrainrain SPECTSPECT:: SStroketroke

AlzhiemerAlzhiemer’’ss DiseaseDisease

CARDIOLOGYCARDIOLOGY

MUGA studyTc-99m RBC

Myocardial perfusion scintigraphy (MPS)Tl-201Tc-99m MIBITc-99m tetrofosmin

Myocardial infarct imagingTc-99m PYP (pyrophosphate)

Myocardial Perfusion StudyMyocardial Perfusion Study

To evaluate the presence of significant coronary artery disease (CAD).Indications

Suspected CADPreoperative evaluationEvaluate extent of myoc ischemia & infarctGuide for treatment-med or revascPre-post revascularization proceduresRisk stratification post MI

MPSMPS:: InformationInformation

1. The presence or absence of significant CAD2. The extent and severity of ischemia or scarring of the myocardium3. Functional information about resting LV wall motion and LVEF. (gated SPECT)4. Information about the stress part of the study which can be treadmill exercise or pharmacological

Single Single vvv Diseasev Disease

GI SGI Systemystem

Esophageal transit timeGE reflux studyGastric emptying timeGI bleeding study

RBC scanMeckel’s diverticulum scan

Liver-spleen scanSpleen scanHepatobiliary scanSalivary scan

GGEE Reflux StudyReflux Study

Other name: Milk scanTechnique:

NPOTc-99m phytate is orally taken.Dynamic imaging to cover E-G junction

Indications: Vomiting, failure to thrive,recurrent pneumoniaInterpretation: Regurgitation of the radioactivity from stomach into eso.

GeGe Reflux Study Reflux Study (Milk Scan)(Milk Scan)

Gastric EmptyingGastric Emptying::

Technique:Tc-99m phytate, In-111 ChlorideLiquid vs solid mealDynamic imaging for 90 min curves

Indications:Dyspepsia, eating disorders DiabetesAfter GI surgery: to evaluate gastric outlet obstruction or "dumping" syndrome.

Gastric Emptying StudyGastric Emptying Study

Normal SolidNormal Solid--LLiquidiquidGastric Emptying StudyGastric Emptying Study

LIQUID SOLID

Lag phase

GI Bleeding StudyGI Bleeding Study

Technique:NPOTc-99m RBC, Tc-99m phytate iv.Dynamic imaging for at least 1 hr.

Indication: Lower GI bleedingMech: ExtravasationPositive: Active bleeding- hot spot,move along peristalsis

Positive GPositive GII Bleeding Bleeding

Extravasation of the tracer into bowel lumenFocal area of increased activity, move // bowel

movementPattern depends on site of bleeding & bowel peristalsis

•Tc-99m RBC

•Hepatic flexure

MeckelMeckel’’s Diverticulum Scans Diverticulum Scan

Technique:NPOTc-99m pertechnetate IV.Serial imaging upto 2 hrs.

Mech:Ectopic gastric localizationNo active GI bleeding required

Indication:Lower GI bleeding in small children

Positive: Abnormal intraabdominal hot spot // gastric activity

MeckelMeckel’’s Diverticulums Diverticulum

Bladder

Stomach

M

Liver Spleen ScanLiver Spleen Scan

Technique:No prep requiredTc-99m phytate iv.Static planar imaging 6 views + SPECT

Uses:Evaluate the size & shape of the liver &spleen, also function (hepatocellular dysfunction (colloid shift)To evaluate SOL-nonspecific !

Liver ScanLiver Scan

Hepatobiliary ScintigraphyHepatobiliary Scintigraphy

Technique:NPO at least 4 hr.Tc-99m DISIDA iv. Mech: HepatocytesDynamic imaging for at least 1 hr

Indications:Acute RUQ pain- acute cholecystitisBiliary tract obstruction, neonatal JxBile leak

Interpretation:Normal-visualize biliary tract,GB, small bowel within 1 hr.

Hepatobiliary ScintigraphyHepatobiliary Scintigraphy

Acute Cholecystitis

Rim signRim sign in acute cholecystitisin acute cholecystitis

curvilinear band of increased activity along the hepatic margin above the GB fossa.The rim sign is identified in about 20-30% of patients with acute cholecystitis,The PPV for acute cholecystitis is about 95% when a rim sign is identified in association with non-visualization of the GB at one hour [9].Approximately 40% of patients who demonstrate the rim sign will have complicated cholecystitis

Rim sign in acute cholecystitisRim sign in acute cholecystitis

Refers to increased pericholecystic hepatic activity without GB visualization.The rim sign appears as curvilinear band of increased activity along the hepatic margin above the GB fossaand is usually identified early in the examination.It may be due to increased flow and/or impaired hepatocyte radionuclide excretion.The rim sign is identified in about 20-30% of patients with acute cholecystitis,The PPV for acute cholecystitis is about 95% when a rim sign is identified in association with non-visualization of the GB at one hour [9].Approximately 40% of patients who demonstrate the rim sign will have complicated cholecystitis (extensive necrosis, perforated or gangrenous GB), thus the presence of this sign indicates the need for more emergent surgery.

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Cystic duct signCystic duct sign

The dilated cystic duct sign refers to a nubbin of activity projecting from the proximal end of the common bile duct medial to the gallbladder fossa.It is believed to represent the a patent cystic duct distal to the site of obstruction.This sign is observed in about 7% of patients with acute cholecystitis and should not be mistaken for a small, shrunken gallbladder.

VentilationVentilation--PPerfusionerfusion Lung ScanLung Scan

Indications:Pulmonary embolismPulmonary hypertensionRt-to-Lt shunt*

Tracer: Tc-99m MAA-Tc-99m phytate or DTPA aerosolViews: 6 planar images [+ head (brain) &posterior abdomen (kidneys)]Interpretation:Ventilation,perfusion,CXR

Multiple hot spotsTechnique:Drawing Pt’s blood into Tc-99m MAA syringe form clumping hot spots

Incorrect Incorrect InjInj TechniqueTechnique

Interpretation of V/Q Lung ScanInterpretation of V/Q Lung Scan

Perfusion lung scanVentilation lung scanCXR within 24 hrs

Criteria: Modified PIOPED criteria NormalHigh-intermediate-low probability

VENTILATION PERFUSION

Normal Lung ScanNormal Lung Scan

Pulmonary EmbolismPulmonary Embolism

RightRight--toto--Left ShuntLeft Shunt

Tc-99m MAA perfusion lung scanPresence of radiotracer in the brain and kidneysPrecaution: Limited MAA particles.

Quantitative Lung Function StudyQuantitative Lung Function Study

Radionuclide Radionuclide VenographyVenography

Tracers : Tc-99m MAA, Tc-99m phytateUses : Venous occlusion (DVT)-proximal deep veins**Technique

IV. injection of the tracer into pedal veins of both feetImaging: during on and off tourniquet over both anklesMultiple overlapping static or whole-body images upto IVC level

* If MAA RNV + Q lung scan (same setting)

Radionuclide Radionuclide VenographyVenography

Genitourinary SystemGenitourinary System

Renal scintigraphyTracers: Tc-99m DTPA (GFR), Tc-99m MAG3, I-131 OIH (ERPF), Tc-99m DMSADiuretic renography: to R/O mechanical urinary tract obstruction.Captopril renography: RVHTTc-99m DMSA scan: renal scarring

Testicular scintigraphyRadionuclide cystography

Direct vs indirect method

Renal Renal ScintigraphyScintigraphy

To evaluate renal perfusionTo evaluate split renal function-relative function (%)To evaluate urinary drainage

DDx functional vs mechanical urinary tract obstruction (good renal function!)

ADVANTAGESNo renal toxicity

Safe for Pts. with renal insufficiencyNo allergy

DISADVANTAGESLimited anatomical details

Flow: 1-2 min

Renograms or Renal time-activity curvesRenal Scan-30 min

Renal Renal ScintigraphyScintigraphy

LT RT

Posterior

L R

Poor Renal FunctionPoor Renal Function

Urinary Tract ObstructionUrinary Tract Obstruction

Diuretic Diuretic RenographyRenography

InterpretationGood response: T1/2 < 10 minEquivocal response: T1/2 10-20 minPoor response: T1/2 > 20 min

Diuretics: FurosemideDose: 0.5-1 mg/Kg IVTiming: 20-30 minutes following radiotracer injection

Tumor ImagingTumor Imaging

Tracers:Nonspecific tumor agents: Ga-67 citrate,Tl-201, Tc-99m MIBISpecific tumor agents: I-131 somatostatin receptor agent, I-131 MIBG*

Indications:Staging-Ga & lymphomaMonitoring therapy: Ga & lymphoma, MIBI & OSMDetect recurrent tumorDDx viable vs fibrosisGuide for Bx

GaGa--67 Scan67 Scan

Abnormal

Normal

DTC s/p TT & RAI Rx with Lt cervical LN metas.

TcTc--99m MIBI Scan99m MIBI Scan

Parathyroid ScanParathyroid Scan

Sensitive modality to detect parathyroid adenoma (or hyperplasia), also ectopic.Sensitivity for adenoma is > 95% and for hyperplasia is between 75 to 85%. Many patients with hyperparathyroidismpresent with bone pain, renal stones, or hypercalcemia.Technique:

Single isotope-Tc-99m sestamibi Dual isotopes- MIBI & TcO4-

Tc-99m Tc-99m MIBI

Parathyroid AdenomaParathyroid Adenoma

II--131131 MIBG SMIBG Scancan

Technique:Prep:

• Lugol’s solution to block thyroid uptake of free iodide

• Avoid drugs interfering MIBG uptakeI-131 MIBG 0.5-1 mCi iv.Whole-body imaging at 24, 48, (72) hrs

Indications:Pheo, NBM, carcinoids, MTCInterpretation:

Normal: adrenal medulla, salivary liver, kidneys,bladder, bowel, heart

II--131 MIBG Scan in NBM131 MIBG Scan in NBM

3 yo girl, NBM stage IV with multiple bone metas 2-44Pretreatment staging

ANT POST

MiscellaneousMiscellaneous

Lymphoscintigraphy

Sentinel node mapping

Bone marrow imaging