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Selective Arterial Injection for the Localization of Gastrinomas and Insulinomas

INDICATION

This investigation is performed in conjunction with highly selective angiography for patients with proven gastrinomas or insulinomas, whose tumours are too small (usually less than 1 cm) to be detected by CT or USS. This comprises about 50% of patients with these syndromes. Gastrinomas can be stimulated with intra-arterial secretin or calcium; insulinomas with intra-arterial calcium.

CONTRAINDICATIONS

(Discuss with radiology S.R.)
Allergy to contrast dye.
Ischaemic Heart Disease
Orthopnoea
Bleeding tendencies (severe)

PREPARATION

Order Secretin (Kabi) or 10% calcium gluconate in advance from Pharmacy.
Warn fasting gut hormone lab (34549/33949) or endocrinology lab (34681) 48 hours in advance.
Stop diazoxide 24 hours before procedure.
Consent patient (may have flushing, nausea and hypoglycaemia following calcium injection, risks of bleeding from sheath sites, thrombosis/dissection of femoral artery and visceral arteries, dye allergy).
Blood for U+Es, clotting, and G+S.
Fast for at least 4 hours and run in 5% dextrose to maintain blood glucose at about 3.0 mmol/l.
2 people to attend to assist sample processing.
7 tubes per arterial run (prepare 4 runs and have more tubes to hand):
7 ml Lithium Heparin tubes (green top Vacutainers) containing 200 µl Trasylol marked before the study starts for gastrinoma.
7 ml plain bottles (red top Vacutainers) for insulinoma.
Syringes.
Ice.
Stopwatch.
Arrangements to transfer for immediate spinning.

SIDE EFFECTS

No serious complications of this procedure have been reported in the 30 patients reported in the literature. Flushing and nausea may follow calcium injection. One of our insulinoma patients had a hypoglycaemic episode following injection of calcium and so BMs should be monitored and the glucose maintained at 3 - 5 mmol/l with dextrose infusion if necessary. The other potential side effects are those of the angiography itself.

METHOD

  1. A catheter is placed in the right hepatic vein prior to routine highly selective visceral angiography.
  2. Following angiography each artery (usually proximal gastroduodenal, proximal splenic, hepatic and superior mesenteric) is recatheterised in turn, preferably starting with the vessels least likely to be supplying the tumour.
  3. Take two baselines at T = -120 and 0 secs.
  4. At T = 0 secretagogue is rapidly injected as a bolus into the artery - 30U secretin in 5ml normal saline or 1 ml of 10% calcium gluconate as appropriate.
  5. Blood is sampled at T = 30, 60, 90, 120 and 180 secs (give a 10 sec countdown before each sample).
  6. Samples for gut hormone assay should be stored in ice and spun within 15 minutes, and samples for insulin assay should be separated within 30 minutes. Do not store insulin samples on ice unless procedure is very prolonged.

INTERPRETATION

  • Secretin injection: localization to a specific region of the pancreas or duodenum (regionalization) is based on a gradient of greater than 50% on the 30 sec sample. Using these criteria the NIH group successfully regionalized 54% of tumours and in combination with angiography, 77% of lesions were localized.
  • Calcium injection: 4 patients have been reported in the literature (by the NIH group). All were localized using the criterion of a two-fold rise in insulin in the 30 or 60 sec hepatic vein samples. There has also been one report of a PPoma being localized by selective arterial calcium injection.

REFERENCES

Secretin: Doppman J.L. et al., Radiology 174, 25-29 (1990).
Calcium: Doppman J.L. et al., Radiology 178, 237-241 (1991), Fedorak I.J. et al., Surgery 113, 242-249 (1993), O'Shea et al., Clin Sci.. Suppl. 31:3 (1994).