THE USE OF I$sup 125$ LABELED DIIODOFLUORESCEIN IN THE DETECTION OF HUMAN INTRAOCULAR NEOPLASMS

Journal Article · Wed Aug 01 04:00:00 EDT 1962 · American Journal of Ophthalmology (U.S.)

DOI:https://doi.org/10.1016/0002-9394(62)93275-0· OSTI ID:4774642

Goren, S B; Newell, E W; Brizel, H E; Harper, P V

The new method which is described is believed to be superior to the usual method for detection of intraocular tumors using P/sup 32/. Because of the limited penetration of beta rays, the use of P/sup 32/ imposes relatively strict geometric restrictions and its usefulness in posterior-segment tumors is limited. The patient receives a single intravenous injection of 5.0 mu c/kg body weight of diiodofluorescein-I/sup 125/, the specific activity of which is 17 mg/mc. External counting over each closed eye is carried out with a hand scintillation counter 1, 5, 8, and 24 hr after injection. Ocular counts are performed by resting the window of the counter against the closed lids; the cavernous sinus is measured by placing the counter just above the bridge of the nose. ln the 17 patients studied, eyes with neoplasms contained at least 23% more radioactivity after 8 hr than did the healthy eye. Control eyes, not containing neoplasms (idiopathic retinal detachment, retinoschisis, benign nevus, macular degeneration, phthisis bulbi, absolute glaucoma), showed less than a 13% differential. One false negative test was obtained, a patient with a metastatic bronchogenic adenocarcinoma to the choroid; no false positives were seen. Diiodofluorescein labeled with I/sup 131/ has been widely used as a diagnostic aid in suspected intracranial neoplasms. However, since the gamma rays of I/sup 131/ have a half-value layer in tissue of 6.9 cm, it has not been helpful in ocular disease; the gamma rays arising from the cavernous sinus interfere with accurate counting of intraocular radiation. I/sup 125/ decays by a complicated scheme, the most important as far as ocular studies are concerned being soft photons of 27.3 and 35.4 kev energies. It has a half-value layer in tissue of 1.9 to 2.5 cm. Therefore, it is feasible to measure radiation of the posterior globe with only minimal interference from radiation arising in the brain sinuses. Its half-life of 60 days results in a greatly increased shelf-life of tagged compounds than when I/sup 131/ is used. Additionally, it has a lower energy of radiation than I/sup 131/ which reduces shielding requirements and permits more efficient detector design. These factors permit enhanced counting efficiency and scanning resolution and lead to a decreased dosage of radiation to the patient. It is thus permissible to use the compound in children in whom P/sup 32/ counting is generally considered contraindicated. However, although the total-body irradiation received during this test is not excessive, it has not been used in pregnant women. The administration of Lugol's solution prior to the test prevents excessive concentration of any free circulating radioactive iodine in the thyroid gland. Diiodofluorescein-I/sup 125/ is not retained by intraocular neoplasms for prolonged periods of time, the most significant counts appearing 8 hr after intravenous injection. About 50% of the injected dose is excreted in the urine and feces within the first 24 hr after injection. The absolute count found in the eye after 8 hr is in the order of 40,000 cpm. After 24 hr, this decreases to approximates 15,000 cpm. The ratio of counts over liver, thyroid, eye, and cavernous sinus is about 4 : 2 : 1 : 0.4. The ratio of counts between the 2 eyes is more significant than the absolute number of counts. This may limit the usefulness of this procedure in monocular patients. (H.H.D.)

• Research Organization: Univ. of Chicago
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-001180
• OSTI ID: 4774642
• Journal Information: American Journal of Ophthalmology (U.S.), Journal Name: American Journal of Ophthalmology (U.S.) Vol. Vol: 54; ISSN AJOPA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ADENOCARCINOMAS
AGE
BETA DECAY
BETA PARTICLES
BIOLOGY AND MEDICINE
BLOOD VESSELS
BODY
BONES
BRAIN
BRONCHI
CANCER
CHOROID
COUNTERS
DECAY
DIAGNOSIS
DIAGRAMS
DISEASES
DISTRIBUTION
DYES
EFFICIENCY
ENERGY
EYES
FLUORESCENCE
FREQUENCY
GAMMA RADIATION
GLANDS
HALF-LIFE
INJECTION
IODINE
IODINE 125
IODINE 131
IODINE COMPOUNDS
IRRADIATION
LABELLED COMPOUNDS
LAYERS
LIVER
LUGOL
LUNGS
MAN
MEASURED VALUES
MEDICINE
METASTASES
PHOSPHORUS 32
PHOTONS
PLANNING
POTASSIUM IODIDES
PREGNANCY
QUANTITY RATIO
RADIATION DETECTORS
RADIATION DOSES
RADIATION PROTECTION
RADIOACTIVITY
RETINA
SCINTILLATION COUNTERS
SCINTILLATIONS
SEX
SHIELDING