Neuroendocrine Tumor Imaging:
 ¹¹¹In-Octreotide

•  PATIENT PREPARATIONS 
   
  • Patient must be very well hydrated before the dose and for up to 48 hr afterward to minimize radiation dose
     
  • Patient must take a mild laxative the evening before administration of the drug and continue for 2 days.

   

• ADMINISTERED DOSE

   

  • For Planar/pediatric imaging: 3 mCi = 111 MBq
     
  • For SPECT imaging: 6 mCi = 222 MBq
     
  • Must perform visual inspection to insure absence of particulates

   

• CONTRAINDICATIONS

  §         Sensitivity to somatostatin and its analogues

   

• ADVERSE REACTIONS
   

          OCCURRING IN  <1% OF ALL PATIENTS

  dizziness	fever	flushing	headache	hypotension
  increased liver enzymes	joint pain	nausea	sweating	weakness

  
          OCCURRING IN  <3% OF ALL PATIENTS

  diarrhea and vomiting

  abdominal pain/discomfort

  injection site pain

  
   

• CLINICAL PHARMACOLOGY

  • Pentetreotide is a long acting analog of the hormone somatostatin
     

  • The ¹¹¹In complex binds avidly to somatostatin receptors throughout the body.
     

  • Initially concentrates in Plasma.
     

  • Within 1 hr, most of the ¹¹¹In octreotide  distributes to extravascular body tissues and in tumors containing a high density of somatostatin receptors.
     

  • After background clearance via the kidneys, visualization of somatostatin-rich receptors is achieved.
     

  • t_1/2 of clearance from blood is 7-8 min
     

  • By 20 hr post injection, <1% of ¹¹¹In activity remains in blood.
     

  • Whole body biological half-life of  ¹¹¹In Octreotide is 6 hr
    
     

• NORMAL DISTRIBUTION OF ¹¹¹In-Octreoscan

   

  • Normal pituitary gland
     
  • thyroid gland
     
  • liver
     
  • spleen
     
  • kidneys
     
  • urinary bladder
     
  • bowel (occasionally)

   

   

•           RADIATION DOSE       (Rads/6 mCi)

   

  Kidneys	10.8
  Liver	2.4
  Spleen	14.8
  Bone Marrow	0.7
  Bladder Wall	6.1
  Stomach Wall	1.1
  Upper GI	1.2
  Lower GI	1.6
  Adrenals	1.5
  Thyroid	1.5

   

   

• CLINICAL IMPACT OF OCTREOSCAN IMAGING

   

  • Yielded information about localizations not previously identified: 27.9% (57/104)
     
  • Demonstrated uptake in lesions known to exist, but not verified as neuroendocrine tumors 28.2% (55/195)
     
  • Localized neuroendocrine tumors in patients with clinical and hormonal evidence of tumor, but no prior localizations 37.5% (21/56)
     
  • Produced a change in patient management-31.1% (64/206)