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Diagnostic dilemmas in parathyroid scintigraphy.
Y Krausz1, E Shiloni, M Bocher
1Department of Nuclear Medicine, Hadassah University Hospital, Jerusalem, Israel. yodphat@hadassah.org.il
Clinical Nuclear Medicine
|November 17, 2001
Summary
Technetium Tc-99m MIBI scintigraphy aids parathyroid adenoma localization. Revising scans, especially with thyroid disease, improves accuracy by addressing rapid tracer washout and using subtraction imaging.
Area of Science:
- Nuclear Medicine
- Endocrinology
- Radiology
Background:
- Parathyroid adenoma localization is crucial for surgical planning.
- Technetium Tc-99m MIBI scintigraphy is a common imaging modality.
- Limited sensitivity and confounding factors like thyroid nodular disease can affect accuracy.
Purpose of the Study:
- To refine the interpretation of Tc-99m MIBI scintigraphy.
- To improve preoperative localization of parathyroid adenomas.
- To analyze false-negative and false-positive results in patients with concomitant thyroid nodular disease.
Main Methods:
- Prospective review of dual-phase Tc-99m MIBI scintigraphy in 77 patients with primary hyperparathyroidism and solitary parathyroid adenomas.
- Inclusion of Tc-99m pertechnetate imaging before surgery.
- Identification and revision of false-negative and false-positive scintigraphic findings.
Main Results:
- Revision of 19 false-negative scans identified adenomas in seven patients, often due to rapid tracer washout.
- Subtraction imaging could have identified two additional lesions.
- Four studies were falsely positive, three associated with thyroid nodular disease, yielding a 91% positive predictive value.
Conclusions:
- Differential washout of Tc-99m MIBI from thyroid and parathyroid tissue is inconsistent.
- Subtraction imaging and contour analysis are recommended for rapid MIBI washout cases.
- Thyroid lesions contribute to, but do not fully explain, false-positive findings.