nuclear medicine in functional disorder of gastrointestinal tract, hepatobiliary system and pancreatic lesions, inflammatory bowel disease, carcinoma of colon, esophageal carcinoma, gist , carcinoid

1. Role Of Nuclear Medicine in GIT
Dr. Kamal Adhikari
MDRD NAMS

2. What is Nuclear Medicine?
• Nuclear medicine is a medical specialty which
uses very small amount of a radioactive
substance or a chemical compound labeled with
a radioactive substance , called
“radiopharmaceuticals” or tracers to image or
treat diseases.
• Type of NM Imaging:
i) Conventional – SPECT or SPECT/CT, Planar,
whole body imaging
ii) Positron emission tomography- PET/CT, PET/MRI

3. ADVANTAGES OF NM IMAGING
• Functional
• Sensitive
• Quantitative
• Very safe
• Minimally invasive
• Low radiation exposure
• Screening
• Follow-up

4. DISADVANTAGES OF NM IMAGING
• Not widely available.
• Give minimal radiation.
• Generally non specific.
• Require NM instruments and
radiopharmaceuticals.
• Higher cost than routine x-ray or USG

5. IDEAL PROPERTIES OF RADIOISOTOPES
• Available.
• Low cost.
• Pure gamma emitter.
• Optimal gamma energy (100-200kev).
• Optimal physical half life.
• Safe.
• Chemically active various
radiopharmaceuticals.
Tc-99m is the most ideal agent.

6. PHYSICAL PROPERTIES Tc-99m VS I-131
Physical Properties Tc-99m I-131
Physical T1/2 6hr 8 days
Radiation emitted gamma ray gamma and beta ray
Energy of gamma ray (keV) 140 364

7. PRINCIPLES OF NM IMAGING

9. NM INSTRUMENTS

11. RADIONUCLIDE IMAGING OF GASTRIC
MOTILITY
• ADVANTAGES:
 Non-invasive and deliver only a very small radiation dose
 Continuous observation of the stomach after a test meal
can be made over a prolonged period, commensurate with
the normal timescale of gastric emptying.
 Liquids and solid test meals used are ‘physiological’ in the
sense that their constituents can be chosen from normal
dietary components.
 Results are quantifiable, so multiple studies can be
compared within the same patient or between patients.
 Technique is simple for the patient.

12. • INDICATIONS:
Patients with persistent nausea, vomiting,
bloating or suspected dumping syndrome.
Suggestive of outflow obstruction but normal
endoscopy.
Suspected non-obstructive gastric stasis eg.
Autonomic neuropathy, thyroid disorders
Severe or resistant reflux esophagitis
Biliary gastritis

15. INTERPRETATION
• Four basic patterns may be observed:
Pattern Liquid phase(t1/2) Solid phase(t1/2)
Normal < 30 min(typically 10-
20min)
> 30 min but at least 25% of
the meal leaves the stomach
by 60min
Vagotomy Normal or rapid Delayed
Dumping pattern Abnormally rapid Abnormally rapid(<30 min )
Gastric stasis Delayed Delayed

18. Pharmacological Interventions
• May be used to help increase accuracy of scan
 Cimetidine – Blocks release of pertechnate
from ectopic mucosa
 Pentagastrin – Enhances mucosal uptake of
pertechnate
 Glucagon – Decrease small bowel motility

19. SCINTIGRAPHIC INVESTIGATION OF
GASTROINTESTINAL BLEEDING
• The indications for scintigraphic investigation
of occult GI bleeding are patient with:
Recurrent episode of bleeding
Endoscopy is inconclusive or negative.
Comorbidities in whom surgical risks are likely
to be high.
Bleeding of sufficient severity to produce
melena.

20. Advantages over contrast angiography include :
Noninvasive
Can detect lower rates of bleed – 0.1 (0.2)cc/min
vs. 1 cc/min with angiography
 Can detect intermittent bleeding
• Disadvantages-
limited to lower GI bleed due to overlaying
activity from liver, spleen

21. GI Bleeding
• Radiopharmaceuticals:
i)Tc 99m sulfur colloid – Rapidly cleared from blood
with a ½ time of 2-3 minutes – Decreased
background – Have to be actively bleeding at time
of injection – Usually not used
ii) Tc 99m labelled RBC
Major advantage over Tc-99sulfur colloid is that
images can be acquired for a longer length of time.
This increases the likelihood of intermittent
bleeding.

22. METHODS OF Technitium-99m RBC
LABELLING

24. SUMMARY PROTOCOL
• Patient preparation : None
• Radiopharmaceuticals : Tc-99m-labelled RBCs
• Instrumentation
-gamma camera : large field of view
-collimator : high resolution , parallel hole
-computer setup : 1 second frames for 60 seconds;
1 minute frames for 60-90 minutes
-as needed upto 24 hours : delayed image
sequence as 1 min frames per 30 minutes.

25. • Patient position
- Supine : anterior imaging with abdomen and pelvis in field
of view
• Imaging Procedure
- Inject patients Tc-99m-labelled erythrocytes intravenously
- Acquire flow images, followed by static images for 60-90
minutes
- Acquire image of neck for thyroid and salivary uptake and
left lateral view of pelvis
- If study is negative or bleeding is recurrent , may repeat 30
minute acquisition.

26. GI BLEEDING SCINTIGRAPHY
(RBC scan)
• Interpretation: Positive = extravasation of the
radiotracer into bowel lumen.
• Bleeding pattern:
i) Central abdomen Small bowel
ii) Peripheral abdomen  Large bowel

29. • Criteria for diagnosis of GI bleeding:
i) Focal activity appears where none was
initially and conforms to bowel anatomy.
ii) Activity increases overtime.
iii) Activity movement along the bowel loop.
iv) Movement may be anterograde or
retrograde.

30. INTERPRETATION OF GI BLEEDING
False Positive
• Free Tc-99m pertechnetate
• Urinary tract activity
• Uterine or penile blush
• Accessory spleen
• Accessory kidney
• Hemangioma
• Varices
False Negative
• Bleeding rate too low
• Intermittent bleeding

31. Tc-99m RBC SCAN VS ANGIOGRAPHY
RBC Scan
• For diagnosis only
• Less anatomical details
• More sensitivity (bleeding
rate 0.04cc/min)
• Good for intermittent
bleeding
• Less invasive
Angiogram
• For diagnosis and
treatment.
• Better anatomical details
• Lower sensitivity (bleeding
rate 0.5cc/min)
• Needs active bleeding
• More invasive

32. MECKEL’S DIVERTICULAM SCAN
• Remnant of omphalomesenteric duct
• Common presentation : Painless lower GI bleeding in small children.
• Imaging:
- Principle : To detect ectopic gastric mucosa
- Patient preparation:
 NPO at least 4 hr
 can perform when when bleeding is inactive
 avoid barium /laxatives/endoscope on the day prior the study.
 pharmacologic augmentation- Cimetidine, ranitidine
• Radiopharm : Tc-99m pertechnetate IV.
• Sequential imaging for 1-2hr.
• Sensitivity 85%, specificty95% .
• Positive : Focal increase activity appears at the same time as stomach,
most common at RLQ.

35. CAUSES OF FALSE POSITIVE RESULTS IN
MECKEL SCAN
1.Urinary tract
- ectopic kidney
- Extrarenal pelvis
- Horseshoe kidney
2. Vascular
- Atriovenous malformation
- Hemangioma
3. Other areas of ectopic gastric mucosa
- Gastrogenic cyst
- Enteric duplication
- Barrett esophagus

36. 4. Hyperemia and inflammatory
- Peptic ulcer
- Crohn disease
- Ulcerative colitis
- Abscess
- Colitis
5. Neoplasm
- Carcinoma of sigmoid colon
- Carcinoid
6. Small bowel obstruction
- Intussception
- volvulus

37. GI bleeding scan
• Generally for adults
• Tc-99m labelled RBC
• Mechanism : Extravasation
of the radiotracer into
bowel lumen.
• Results: Not specific.
• Active bleeding during the
scan is required.
Meckels scan
• Generally for children with
suspected for Meckel’s
bleeding.
• Tc-99m pertechnatate.
• Mechanism : ectopic gastric
mucosa localization.
• Results : Specific.
• Active bleeding during the
scan is unnecessary.

38. RADIONUCLEIDE IMAGING OF
INFLAMMATORY BOWEL DISEASE
• Uses autologous WBC labelled either with
Technitium 99m or with indium -111.
• Advantages of Tc-99m over Indium-111 :
Less radiation hazard to the patient
So more activity and higher count rate can be
achieved
Localization is rapid and images can be
diagnostic at 1hour and delayed views being
obtained at 4 hour.

39. OPTIMAL IMAGING TIME FOR
INFECTION-SEEKING
RADIOPHARMACEUTICALS
RADIOPHARMACEUTICALS TIME(HR)
Ga-67 48
In-111 leukocytes 24
Antigranulocyte monoclonal antibody 1-6
Technitium-99m HMPAO leukocytes 1-4
Chemotactic peptides 1-4
F-18 FDG 1

40. ADVANTAGES AND DISADVANTAGES
OF Indium-111 Oxine VS Technitium-
99m HMPO labelled leukocytes
Advantages and disadvantages In-111 oxine WBC Tc-99mHMPAO
Radionucleide immediately available No Yes
Stable radiolabelled, no elution from cells Yes No
Allows labelling in plasma No Yes
Dosimetry Poor Good
Early routine imaging No Yes
Long half life allows for delayed imaging Yes No
Imaging time Long Short
Bowel and renal clearance No Yes
Image resolution Good Fair

41. • Disadvantages of Technitium-99m
Greater proportion of renal excretion, more
bone marrow uptake of the agent.
Phenomenon of migration of the agent into
the lumen of the bowel , particularly in the
colon , within few hours of injection.

42. Applications
1. Detecting inflammatory bowel disease
- may be the only positive test , particularly
in early small bowel Crohn’s disease.
2. Assessing the extent and location of
abnormal bowel
- can show which areas of the small bowel
and colon are involved and also assess the
intensity of inflammatory change in each area.

43. 3. Follow up
-in assessment of progression of the disease, WBC
scintigraphy offers a relatively non-invasive method that is
well tolerated by the patient.
4. Assessing complication
- Differentiate between infected collections and pockets of
sterile fluid or localised loops of dilated small bowel, which
may be confusing on USG/CT.
- Assessment of strictures: those with inflammatory changes
may be amenable to medical treatment whereas strictures
which are inactive on WBC scintigraphy are more likely to
need surgical intervention.

44. INTERPRETATIVE PITFALLS IN
LEUCOCYTE IMAGING
FALSE NEGATIVE
• Encapsulated , non pyogenic
abscess
• Vertebral osteomyelitis
• Chronic low grade infection
• Parasitic, myocobacterial
,fungal infections
• Hyperglycemia
• Corticosteroid therapy
FALSE POSITIVE
• GI bleeding
• Healing fracture
• Surgical wounds , stomas
• Hematomas
• Tumors
• Accessory spleens
• Renal transplant
• Pseudoaneurysm

45. Liver-Spleen Imaging
• Radiopharmaceuticals is Tc99m sulfur colloid
• Particles are phagocytized by
reticuloendothelial cells found in the Liver,
Spleen and Bone marrow
• Under normal circumstances 80-90% taken up
by the liver, (L>>>>S>>>BM)
• Uptake and distribution depends on having
functioning reticuloendothelial cells as well as
perfusion to the organs

46. CAUSES OF INCREASED FOCAL LIVER
UPTAKE ON Technitium-99m Sulfur
Colloid Imaging
• Superior venacava syndrome
• Focal nodular hyperplasia
• Budd-chiari syndrome
• Cirrhosis(regenerating nodule)

47. Splenic Imaging
• On a normal Tc99m colloid scan, spleen
exhibits homogeneous activity less than or equal
to liver.
• Isolated imaging of spleen is performed with
heat damaged Tc99m.

48. Abnormal Splenic Scan
• Solitary or multiples defects are nonspecific –
Cysts, hematoma, abscess, infarct, neoplasm
• Peripheral wedge shaped defects correspond
to infarcts
• Metastatic lesions – Uncommon – Can see in
lymphoma, melanoma or soft tissue sarcoma –
Primary splenic lesions are rare

49. Abnormal Splenic Scan
• Focal decreased areas of in the spleen – Seen in
less that 1 % of scans – If no history of trauma then
etiologies 1/3 each infarct, lymphoma, and abscess.
• Nonvisualization of spleen – History of
splenectomy – Congenital asplenia – Sickle cell
anemia- atrophy secondary to repeated infarctions
(auto-splenectomy) – Transfusions with normal rbc
– Functional asplenia -post op splenic hypoxia, graft
versus host disease, lupus

51. HEPATOBILIARY SCAN
• Indications:
 Biliary tract obstruction
 Acute cholecystitis
 Choledochal cyst
 Bile leak
 Radiotracer : 99m Tc-DISIDA IV
 Patient preparation:
- NPO 4-6 hr
- Phenobarbitone : 5mg/kg/day X 5days prior to study
for biliary atresia to increase sensitivity of the test.

52. HEPATOBILIARY SCAN
• Principles of test : Uptake in hepatocytes and
then excreted via the biliary tract.
• Imaging technique:
- Dynamic study for at least 1 hour +/- delayed
imaging upto 24 hrs in cases with cholestatic
jaundice.
- Visualization Liver and biliary system
including gall bladder until excretion into small
bowel (normal=within 1 hour)

53. NORMAL HB SCAN
• Visualization : Liver and
biliary system including
- right and left hepatic ducts
- common hepatic duct
- common bile duct
- Gall bladder
- until excreted into small
bowel
• Within 1 hour

54. Biliary Obstruction
• Complete obstruction – Non-visualization of
the biliary tree – Good visualization of liver –
Liver scan sign – Mechanical or Functional –
Stones – Tumor – Ascending cholangitis
• Partial obstruction – Biliary tree visualized to
level of obstruction – Stone, stricture –
Sphincter – Tract Dysfunction

58. Post Surgical Biliary Scans
• Evaluate for biliary leaks after cholecystectomy –
Higher rate of leaks with laparoscopic
cholecystectomy – Cystic duct most common
location due to clips slipping off
• Increasing activity/compound in the GB fossa,
over the dome of liver, under the liver, pericolonic
gutters and pelvis
• If study appears negative after an hour – Have
patient move around – Reposition patient –
Delayed imaging – Include pelvis

59. Biliary Atresia and Neonatal Hepatitis
• Early diagnosis is critical because surgery must
occur within 60 days of life
• Pretreat with Phenobarbital (5 mg/kg/d for 5
days) activates liver excretory enzymes
• Biliary atresia – Demonstrates no passage of
Radiolabeled bile through the liver and biliary tract
– No GI activity seen out 24 hour – Gallbladder can
be seen
• Neonatal hepatitis – May or may not see activity
in the bowel – Can have decrease uptake by liver /
increased background

61. • Findings favor biliary atresia:
Good hepatic function
No radioactivity excretion into small bowel
upto 24 hours.

62. Acute Cholecystitis
• Rim Sign – Curvilinear band of increased activity
in the right inferior liver edge above the GB fossa –
Inflammatory changes / increase blood to Liver by
GB – 40% of these patients have a perforated or
gangrenous GB – If patient has rim sign and
decreased signs and symptoms – perforated GB
• Cystic duct sign – Small nubbin of activity in the
cystic duct proximal to the site of obstruction

65. SOMATOSTATIN RECEPTOR
SCINTIGRAPHY
• Somatostatin analogue octreotide (more
stable and longer t1/2) is used.
• 111In-DTPA octreotide is used
• Indications :
Localisation of pancreatic islet cell tumors and
their metastasis.
Investigation of gastrointestinal carcinoids,
apudomas and related tumors and their
metastases.

66. • Results:
1. SRS is highly accurate (probably more sensitive than
CT or MRI) in detecting primary bowel carcinoids and
their metastases in mesenteric lymph nodes.
2. In differentiating carcinoids from non functioning
tumors, SRS may eliminate the need for biopsy.
3. SRS is also useful for staging of carcinoid tumors.
4. Functioning tumors which show marked uptake of
octreotide on SRS usually also respond well to
unlabelled octreotide for the relief of symptoms.

69. FDG-PET FOR GI TUMORS
• Colorectal carcinoma:
FDG PET for recurrence detection
More sensitive and specific compared to CT
More sensitive for detection of hepatic
metastasis compared to CT/MRI.
Sensitvity of FDG PET is more than CT in all
location except lungs where they are equivocal
Specificity of FDG PET is more than CT in all
location except retropertoneum

70. • The ability of PET to diagnose primary colorectal
tumors may be limited because small tumors and
cancerous polyps are not detected as high levels
of normally occurring F-18 FDG activity in the
bowel results in decreased sensitivity.
• GIST : These tumor show high level of F-18 FDG
accumulation. Tumors which responds to
Imatinib therapy, show marked decreased F18
FDG accumulation in PET within days. Helpful in
early response than CT and predicts improved
patient survival.

71. • Esophageal carcinoma
diagnosis- sensitivity >
90%(SCC>adenocarcinoma)
Accuracy of detecting lymph nodes involvement
with F-18 FDG PET (with PET/CT) has been
consistently shown to be higher than that of
CT/MRI.
PET has proven value in assessing patients during
therapy and after therapy for
recurrence(restaging and monitoring response to
therapy).

72. Esophageal transit
• Most often use compound: Tc99m Sulfur colloid
1.0 mCi
• Used to evaluate scleroderma and achalesia
• Fast for 6 hours before study
• Patient is placed supine under the gamma
camera, including esophagus and proximal stomach
• Swallow the radiopharmaceutical in 10 cc of
water then dry swallows every 15 seconds for 5
minutes

73. Esophageal transit
• Esophagus is divided into thirds with a region
of interest over each third to generate activity
curves
• Normal esophageal transit times for water is 5-
11 seconds and at least 90% should have trans
versed the esophagus by 15 seconds
• Patients with scleroderma and achalasia may
have values as low as 20-40%

74. • It is important to remember that esophageal
scintigraphy is functional and does not
provide detailed anatomic information.
• Barium or endoscopic study is necessary to
exclude the possibility of neoplasm or
infection as the cause of impaired esophageal
function.

76. C-14 Urea breath test
• The C-14 urea breath test (UBT) is an inexpensive ,
accurate , non-invasive test for active infection with
H.Pylori.
• For the UBT, a patient needs to be fasting and off
antibiotics, bismuth, and proton – pump inhibitors.
• A 1 mCi capsule of C-14 labelled urea is administrated
by mouth and then 10 minutes later a breath sample is
collected.
• H.pylori contains an enzyme , urease, which hydrolyze
the urea into ammonia and C-14-labelled CO2 that is
subsequently detected in the breath sample using
liquid scintilation techniques.

77. Ascites Scan
• Evaluate congenital communication between
peritoneal cavity and thorax
• Traumatic perforations of the diaphragm
• Intraperitoneal injection of 5 mCi Tc 99m
Sulfur Colloid
• Image abdomen and thorax

78. Salivary Scanning
• A quick look at he salivary glands of the mouth is
frequently had in conjunction with the Tc-99m
pertechnate (Tc-99m-O4).
• Salivary glands can be scanned intentionally with
Tc-99m-O4.
• The salivary scan can demonstrate salivary
obstruction and can be used as an adjunct to or
replacement for sialography.
• A salivogram can also be accomplished by
swabbing a childs mouth with radiotracer.

80. THANK YOU

81. REFERENCES:
- Textbook of radiology and imaging(7th edition)
- Nuclear medicine : the requisites (4th edition)