RADIONUCLIDE STUDIES OF RADIONUCLIDE STUDIES OF THE GASTROINTESTINAL SYSTEMTHE GASTROINTESTINAL SYSTEM

Jiraporn Sriprapaporn, M.D.Nuclear Medicine, Radiology,

Siriraj Hospital

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GASTROINTESTINAL SYSTEMGASTROINTESTINAL SYSTEM

Esophagus

Stomach:

Intestine

Eso transit timeGE reflux (milk scan)

Gastric emptying studyEctopic gastric mucosa localization

GI bleeding study

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GASTROINTESTINAL SYSTEMGASTROINTESTINAL SYSTEM

Liver-spleen

Biliary system

Nonspecific SOLTumor/infectionHemangioma

Hepatobiliary imaging

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THE LIVERTHE LIVERThe biggest organ, 1500 gAnatomy: 4 parts- Right, Left, Caudate, and Quadrate lobesHistology:

Hepatocytes or polygonal cellsRE cells (Kupffer’s cells)

Blood Supply: Portal vein 75 %Hepatic artery 25 %

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FUNCTIONS OF LIVERFUNCTIONS OF LIVER

Bile formation (Hepatocytes)

Phagocytosis (RE cells)Protein synthesis, eg. albumin,fibrinogenMetabolizes substances

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LIVERLIVER--SPLEEN SCAN SPLEEN SCAN (Routine Liver Scan)(Routine Liver Scan)

Tracer: 99mTc-sulfur colloid/ phytateRoute : IV injectionMechanism : Phagocytosis by RE cells (liver, spl, BM)Visualization : Liver and SpleenTechnique:

Patient preparation : noneImaging : 15-20 min. Pi.

: Static 6 views- Ant, Post, RL, LL, RAO, LAODiagnosis : Diffuse & focal lesions focal defect(s) -nonspecific (abscess, metastasis, cyst etc.)

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Colloid ParticlesColloid Particles

< 100 nm Bone marrow

200-1,000 nm Liver

1-5 um Spleen

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TcTc--99m Sulfur Colloid99m Sulfur Colloid

Size: 100-500 nm (1-5 um)Distribution of Uptake

Liver: 80-85 %Spleen: 12 %Bone marrow: The rest

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NORMAL LIVER SCANNORMAL LIVER SCAN

Liver and spleen visualizationNormal colloid distributionUniform colloid distribution (no defect)

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Evaluate shape,size,positionSOL in the liver-spleen:

Cold defect*: nonspecific(metasastases***)

Hot lesion

Diffuse hepatocellular disease : COLLOID SHIFT (Decreased hepatic, increased splenic& BM uptake) Ex. Cirrhosis

LIVER SCAN: Clinical ApplicationsLIVER SCAN: Clinical Applications

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COLLOID SHIFTCOLLOID SHIFT

PathophysiologyChange in blood flow Hepatocellular impairmentStimulation of RE system

FindingsDecreased hepatic uptakeIncreased splenic & BM uptake

Ex. Cirrhosis

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LIVER SCANLIVER SCAN

ROUTINE LIVER SCAN : Tc-99m sulfur colloid (SC) or Tc-99m phytateLIVER SCAN with other R’pharmaceuticals

Tc-99m RBC for Hepatic HemangiomaTc-99m HMPAO-WBC for infection img.Ga-67 scan for tumor/infection imagingTl-201, Tc-99m MIBI for tumor imaging

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Hepatic Blood Pool Scan (Hepatic Blood Pool Scan (99m99mTcTc--RBC)RBC)

Aim : To Dx hepatic hemangiomaSensitivity: SPECT almost 100% for > 1.5 cm lesionsTechnique :

Flow: normal or decreased Static images: may be cold initiallyDelayed images *** hot lesions

Positive : Increased activity in the lesion with time

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HEPATIC HEMANGIOMAHEPATIC HEMANGIOMA

Vascular Study 3-D image

SPECT

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HEPATIC HEMANGIOMAHEPATIC HEMANGIOMA

U/S

Tc-99m RBC Scan

Planar

RBC

SPECT

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SimpleNot operator-dependentMinimally invasiveNot expensiveLess sensitiveLess specificNature: nonspecificDiffuse & focal dis.Minimal radiationAnatomy: intrahepatic

RapidOperator-dependentAbsolutely noninvasiveNot expensiveMore sensitiveMore specificNature: Cystic vs solidFocal > diffuseNo radiationAnatomy: intra-extrahep.

LIVER SCANLIVER SCAN UU//SS

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More expensiveMore radiationGood anatomic details

IntrahepaticExtrahepatic

Mor available

Most expensiveNo radiationExcellent anatomic details

IntrahepaticExtrahepatic

Less available

CT SCAN CT SCAN MRIMRI

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CONCLUSIONCONCLUSION:: LIVER SCANLIVER SCAN

Liver metastases**Role of radionuclide study Role of U/S , CT, MR Tc-99m RBC for hemangioma !

SPECT/CT will enhance sensitivity & specificity of the test.

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SLLEEN SCAN

Radiopharmaceuticals: Tc-99m sulfur colloid, Tc-99m phytate: phagocytosis by RE cellsTc-99m heat-denatured red cell: cell sequestration (specific for splenicfunction)

Indication: Accessory spleen, splenic infarct

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A 56-year-old woman who underwent splenectomy two years ago for idiopathic thrombocytopenic purpura (ITP) continues to have thrombocytopenia

Planar and SPECT images of the abdomen ( Tc-99m in vitro-labeled heat-damaged red blood cells)

Two foci of increased activity are seen in the posterior aspect of the left upper quadrant consistent with residual splenic tissue.

http://nucmed.richis.org/case/Infec/MIRsi0201.htm

HEPATOBILIARY IMAGINGHEPATOBILIARY IMAGING

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Radiopharmaceuticals for Radiopharmaceuticals for HepatobiliaryHepatobiliary ImagingImaging

Tc-99m Iminodiacetic acid) IDA derivativesTc-99m diisopropyl IDA (DISIDA or Disofenin)Tc-99m trimethylbromo IDA (Mebrofenin)

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Tracers : Tc-99m IDA derivatives (Tc-99m DISIDA, Mebrofenin)Route : IV injectionMechnism : Carrier-mediated, non sodium dependent organic anion transport processTecnique : -Fasting 4-6 hr

-Dynamic study for at least 1 hour +/- delayed imaging

Visualization : Liver and biliary system including gallbladder until excretion into small bowel (Normal within 1 hour)

HEPATOBILIARY SCANHEPATOBILIARY SCAN

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HEPATOBILIARY SCAN:HEPATOBILIARY SCAN:IndicationsIndications

Gallgladder diseaseAcute cholecystitis*

Biliary tract obstructionDDx biliary atresia vsneonatal hepatitis

Biliary leakage

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NORMAL HEPATOBILIARY SCANNORMAL HEPATOBILIARY SCAN

Visualization :Liver and biliarysystem including

Right & left hepatic ductsCommon hepatic ductCommon bile ductGallbladder Until excreted into small bowel

Within 1 hour

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NORMAL HEPATOBILIARY SCANNORMAL HEPATOBILIARY SCAN

Tc-99m DISIDA

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NONVISUALIZED GALLBLADDERNONVISUALIZED GALLBLADDER

Acute cholecystitisSevere chronic cholecystitisProlonged fastingIntercurrent severe illnessAcute pancreatitisSevere liver disease

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BILIARY ATRESIABILIARY ATRESIA

Early images 24-hr image

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NEONATAL HEPATITISNEONATAL HEPATITIS

1 hr

4 hr

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GI BLEEDING STUDYGI BLEEDING STUDY

Lower GI tractActive bleedingTc-99m SC or Tc-99m RBC* (intermittent)More sensitive than angiography but less anatomical detailsLess specific in nature

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GI BLEEDING STUDYGI BLEEDING STUDY:: TECHNIQUETECHNIQUE

Preparation: NPOPosition: SupineRegion: Anterior- lower abdomenImaging:

Flow 1 minDynamic imaging for 1-2 hr with additional delayed images as required.

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POSITIVE FINDINGSPOSITIVE FINDINGS

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

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Bleeding 500+ ml/ 24hr.Bleeding rate 0.1-0.5ml/minIntermittent bleeding-24h F/U wo reinjectionLower T/B ratio (higher Bcg)Upper & lower GI bleeding

T1/2 in bl pool 2.5-3 minBleeding rate 0.05-0.1ml/min*Intetrmittent bleeding requires reinjection Higher T/B ratio (lower Bcg)Upper abd interfered by liver-spleen activity

TcTc--9999m RBCm RBC TcTc--9999m SCm SC

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MeckelMeckel’’ss ScanScan

Meckel’s diverticulum represents a persistence of the omphalomesenteric (vitelline) duct at its junction with the ileum.Meckel’s diverticulum is the most common cause of lower GI bleeding in small children.Meckel's are disease of “2”Most of the patients are asymptomatic (80%). Gastric mucosa is most commonly found mucosal lining in the Meckel’s.Most common Sx is painless blood per rectum-gastric mucosa was found in 95% of bleeding lesions.

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MeckelMeckel’’ss ScanScan

Indication: bleeding per rectum in small childrenRadiopharm: Tc-99m pertechnetate, IVMechanism: Localization of ectopic gastric mucosaImaging:

Patient preparation: NPO 4 hrSequential abdominal imaging for 1-2 hr.Positive findings: Focal hot spot (RLQ) //stomach activitySen 85%, spec 95%

No need for active bleeding during the scan

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MeckelMeckel’’ss DiverticulumDiverticulum

Bladder

Stomach

M

Stomach

U. Bladder

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GASTROESOPHAGEAL STUDYGASTROESOPHAGEAL STUDY

1. Esophageal transit study : dysphagia

2. Gastroesophageal reflux study (milk scan): GE reflux

3. Gastric emptying study : dyspepsia

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DISEASES OF THE ESOPHAGUSDISEASES OF THE ESOPHAGUS

Motility disorders of the esophagus: scleroderma, achalasiaGastroesophageal reflux & related disordersStructural lesions of the esophagus: tumors, rings, webs

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GASTROESOPHAGEAL STUDYGASTROESOPHAGEAL STUDY

1. Esophageal transit study

2. Gastroesophageal reflux study (milk scan)

3. Gastric emptying study

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ESOPHAGEAL TRANSIT STUDYESOPHAGEAL TRANSIT STUDY

Indications: swallowing difficulty eg. dysphagia, heartburnRadiopharm: Tc-99m SC - neither absorbed nor secreted by esophageal mucosa, 150-500 uCiTechnique:

4-6 hr fastingLiquid*: Water = most common, 10 ml bolusPosition: Upright* ( more physiological & is preferable or supine ( no effect of gravity)Acquisition: Dynamic imaging 0.8 s x 240 s

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ESOPHAGEAL TRANSIT STUDYESOPHAGEAL TRANSIT STUDY

Interpretation:At 15 sec post bolus swallowing, >90% of radioactivity passed into the stomach

Quantification:

3 regions Time-activity curves

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GASTROESOPHAGEAL STUDYGASTROESOPHAGEAL STUDY

1. Esophageal transit study

2. Gastroesophageal reflux study (milk scan)

3. Gastric emptying study

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GE REFLUX STUDY GE REFLUX STUDY (MILK SCAN)(MILK SCAN)

Indication: To detect GE reflux:- regurgitation of gastric contents esophagusTracers : Tc-99m phytate, Tc-99m SC 300 uCiTechnique :

NPO, oral tracer adm. Within 30 sSupine imaging over EG junctionDynamic for >10-20min. Views: anterior ( & posterior)

Positive : Activity from the stomach esophagusN < 3 %, Abn >4 %

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GE REFLUX STUDY GE REFLUX STUDY (MILK SCAN)(MILK SCAN)

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GASTROESOPHAGEAL STUDYGASTROESOPHAGEAL STUDY

1. Esophageal transit study

2. Gastroesophageal reflux study (milk scan)

3. Gastric emptying study

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THE STOMACHTHE STOMACH

AnatomyFundus: reservoirBody: grinderAntrum : propeller, grinder

Pylorus: particles < 1 mm passPhysiology: Vagus N, ANS

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Rate of gastric emptyingRate of gastric emptying

Types & compositions of food: Physical state: Liq-exponential, solid-linearParticle sizeCaloric contents: Fat delays GE0Fiber contentsCaloric densityAcididy & viscosity

Volume of foodNeuro regulartory factors

Liquid

Solid

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Rate of gastric emptyingRate of gastric emptying

SexAgeObesityConcomitant

diseases eg. DM Position

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GASTRIC EMPTYING STUDYGASTRIC EMPTYING STUDY

Clinical indications: Dyspepsia, dumping syndromeTracers :

Solid: Tc-99m phytate, Tc-99m SC 1 mCi, OralLiquid: In-111 Cl 100 uCi

Technique :NPO, upright, eat within 10 min

Dynamic imaging for 120min. Views: anterior & posterior (geometric means) or LAO

CG =[CA . Cp ]1/2

CG = Counts calculated by geometric mean

CA = Counts in anterior view

Cp = Counts in posterior view

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GASTRIC EMPTYING STUDYGASTRIC EMPTYING STUDY

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INTERPRETATION OF GETINTERPRETATION OF GET

Half-emptying time (T1/2)= 50 % emptying

Normal T1/2 (min)Phase Males FemalesSolid 77 + 32 92 + 7.5Liquid 38 + 26 53.8 + 4.9

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NORMAL SOLIDNORMAL SOLID--LIQUIDLIQUIDGASTRIC EMPTYING STUDYGASTRIC EMPTYING STUDY

LIQUID SOLID

Lag phase

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GEOMETRIC MEANGEOMETRIC MEANATTENUATION CORRECTIONATTENUATION CORRECTION

CGM= [CANT . CPOST]1/2

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DUALDUAL--PHASE SOLIDPHASE SOLID--LIQ GASTRIC LIQ GASTRIC EMPTYING STUDYEMPTYING STUDY

A: Normal subject, N solid & liq emptyingB: DM, N solid & liq emptyingC: DM, delayed solid, N liq emptyingD: DM, delayed both solid & liq emptying

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DIABETIC GASTROPARESISDIABETIC GASTROPARESIS

A: Baseline study

B: 2 wk after metoclopramide Rx

C: 1 wk after cisapride Rx

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SUMMARYSUMMARY

Esophagus: Milk scanStomach: Gastric emptying studyIntestine: GI bleedingLiver-spleen: Tc-99m SC or phytate, RBCBiliary system: Hepatobiliary