Keywords:
Head and neck, Thyroid / Parathyroids, CT, Audit and standards, Endocrine disorders
Authors:
L. M. Loy1, S. W. Kheok2, L. E. McAdory2; 1SINGAPORE, SINGAPORE/SG, 2Singapore/SG
DOI:
10.26044/ecr2019/C-0206
Results
14 patients (11 Chinese,
2 Malays,
1 Indian) met our inclusion criteria.
The mean age of the patients was 60.1 ± 9.7 years,
with 78.6% of the patients female.
All 14 patients had elevated serum PTH and calcium levels prior to surgery.
Sestamibi and US results were negative and discordant in 3 and 5 patients respectively.
4 patients had concordant,
positive sestamibi and US results but were referred for 4D CT scan for further confirmation.
2 patients did not have both sestamibi and US results available prior to 4D CT scan.
The performance of 4D CT in localization of parathyroid lesions poorly localized by sestamibi and US (Table 1) as well as pre-operative localization of all 14 patients (Table 2) was comparable to results from similar studies on Caucasian patients.
[2,
6,
7]
Statistical parameter
|
Lateralization
|
Localization
|
95% CI
|
Lateralization
|
Localization
|
Sensitivity (%)
|
100
|
83
|
54.1 - 100.0
|
35.9 - 99.6
|
Specificity (%)
|
80
|
85
|
44.4 – 97.5
|
65.1 - 95.6
|
Positive predictive value (%)
|
75
|
56
|
46.5 - 91.2
|
32.2 - 76.7
|
Accuracy (%)
|
88
|
84
|
61.7 - 98.5
|
67.2 - 94.7
|
Table 1: Diagnostic parameters for the 8 patients whose sestamibi and US results were negative or discordant
Statistical parameter
|
Lateralization
|
Localization
|
95% CI
|
Lateralization
|
Localization
|
Sensitivity (%)
|
92
|
83
|
61.5 - 99.8
|
51.6 - 97.9
|
Specificity (%)
|
81
|
84
|
54.4 - 96.0
|
69.9 - 93.4
|
Positive predictive value (%)
|
79
|
59
|
56.6 - 91.2
|
40.9 - 74.7
|
Accuracy (%)
|
86
|
84
|
67.3 - 96.0
|
71.7 - 92.4
|
Table 2: Diagnostic parameters for all 14 patients
The accompanying figures show the scan results of a patient who had negative sestamibi and US results but had a parathyroid adenoma subsequently localized by 4D CT.
Fig 1) Tc-99m Sestamibi images of the neck and chest were obtained up to 25 minutes after intravenous injection.
A delayed image was also obtained at 1.5 hours.
Early sestamibi images demonstrated increased tracer uptake at the lower pole of the right thyroid but this washed out together with the rest of the thyroid gland in the 1.5hour delayed image.
Ultrasound (not shown) did not reveal an extrathyroidal nodule,
particularly at the right lower pole.
Hence,
no suspicious parathyroid adenoma was identified in the combined Tc-99m Sestamibi and US scans.
Fig 2) Non contrast phase of CT neck revealed a small,
isodense,
extrathyroidal nodule posterior to the upper pole of the right thyroid gland.
Fig 3) Arterial phase of CT neck demonstrated avid contrast uptake of the nodule.
Fig 4) Venous phase of CT neck showed that the nodule had contrast washout.