GI Bleeding Scan รศ. พญ. มลฤดี เอกมหาชัย หน่วยเวชศาสตร์นิวเคลียร์ ภาควิชารังสีวิทยา คณะแพทยศาสตร์ มหาวิทยาลัยเชียงใหม่

GI Bleeding 1. Upper GI bleeding 2. Lower GI bleeding

Diagnostic Procedures 1. Endoscopic examination 2. Selective angiography 3. GI bleeding scan

Acute Lower GI Bleeding 1. Small bowel bleeding 2. Large bowel bleeding

Causes of Small Bowel Bleeding w Regional enteritis w Intestinal varices w Lymphoma w Heriditary telangiectasia w Meckel’s diverticulum etc.

Causes of Large Bowel Bleeding w Diverticulosis w Inflammatory diseases w Arteriovenous malformation w Angiodysplasia w CA colon, Polyps etc.

Acute Lower GI Bleeding 1. Rigid endoscopy (Proctosigmoidoscopy) 2. Selective angiography 3. GI bleeding scan

Algorithm for the Dx & Rx of Acute Lower GI Hemorrhage Acute Lower GI Bleeding Proctosigmoidoscopy Rectal fissure, Bleeding site not found Hemorrhoids, Polyps or CA etc. GI bleeding scan Surgery or Therapeutic angiography

Algorithm for the Dx & Rx of Acute Lower GI Hemorrhage GI bleeding scan Positive scan Negative scan Angiography, Medical treatment Transcatheter Rx Elective colonoscopy Persistent bleeding Barium studies, CT etc Surgery

GI Bleeding Scan 1. Tc99m-Sulfur Colloids 2. Tc99m-labeled Red Blood Cells

Tc99m-Sulfur Colloid Scan w Dose 10 mCi IV w Circulation half-time min w Active bleeding within min w Minimal bleeding rate ml/min

Mechanism w To demonstrate an acute GI bleed Extravasation of activity (increased uptake)

Time-Activity Curves

Negative Tc99m- Sulfur Colloid Scan w Normal uptake in - Liver - Spleen & - Bone marrow

Positive Tc99m- Sulfur Colloid Scan w Normal uptake in liver, spleen & bone marrow w Extravasated activity at bleeding site(s)

Tc99m-labeled Red Blood Cell Scan w Dose 20 mCi IV w Active or intermittent bleeding w Minimal bleeding rate 0.35 ml/min

Negative Tc99m- RBC Scan w High uptake in - Blood pool organs & - Great vessels of abdomen

Positive Tc99m- RBC Scan w Normal uptake in blood pool organs & great vessels w Extravasated activity at bleeding site(s)

Scintigraphic Criterias for Dx of GI Bleeding 1. Area(s) of extravasated activity (increased uptake) - Appears and - Conforms to bowel anatomy

Scintigraphic Criterias for Dx of GI Bleeding w 2. Area(s) of extravasated activity - Persistence or - Increased in intensity with time

Scintigraphic Criterias for Dx of GI Bleeding 3. Area(s) of extravasated activity can change in - Size - Configuration & - Location with time.

Scintigraphic Criterias for Dx of GI Bleeding 4. Area of extravasated activity does not initially present, but appears in later images. (intermittent bleeding)

Advantages of GI Bleeding Scan w Noninvasive w More sensitive w Low cost w Low radiation exposure w Active or intermittent GI bleeding w Venous or arterial bleeding

Tc99m-RBC Tc99m-S.Colloid w Dose 20 mCi IV w More complicated w Noninvasive w Low radiation exposure w Lower target/nontarget ratio w Active or intermittent bleeding w Bleeding rate >0.35 ml/min w Venous or arterial bleeding w Dose 10 mCi IV w Simple w Noninvasive w Low radiation exposure w Higher target/nontarget ratio w Active bleeding w Bleeding rate > 0.1 ml/min w Venous or arterial bleeding

Negative Tc-99m Sulfur Colloid Scan

Small Bowel Bleeding

Terminal Ileal Bleeding

10 min 20 min

Ascending Colon Bleeding 10 min 20 min

5 min 30 min

Ascending Colon Bleeding 5 min 30 min

Mid Descending Colon Bleeding

Descending Colon Bleeding

Sigmoid Bleeding

Rectal Bleeding

Negative Tc-99m RBC Scan 5 min 15 min 30 min 1 hour

Blood pool image Dynamic study 2sec/Frame

Active Jejunal Bleeding

1 hr 2 hrs 3 hrs 4 hrs

Small Bowel Bleeding 1 hr 2 hrs 3 hrs 4 hrs

45 min 1 hour 2 hrs 3 hrs

Small Bowel Bleeding 45 min 1 hour 2 hrs 3 hrs

Small Bowel Bleeding

15 min 1 hour 2 hrs 2:30 hrs

Intermittent Colon Bleeding 15 min 1 hour 2 hrs 2:30 hrs

1 hour 1:15 hrs 10 min 30 min

Mid Transverse Colon Bleeding 1 hour 1:15 hrs 10 min 30 min

5 min 15 min 30 min 45 min

Rectosigmoid Bleeding 5 min 15 min 30 min 45 min