Elizabeth J. Bernard

Comparison of pinhole and SPECT 99mTc-MIBI imaging in primary hyperparathyroidism.

ObjectiveThis study aims to compare dual tracer, dual phase pinhole technetium-99m labelled 2-methoxyisobutylisonitrile (99mTc-MIBI) imaging (including oblique imaging), with single photon emission computed tomography (SPECT) and dual phase planar 99mTc-MIBI images, and combined SPECT, dual phase planar 99mTc-MIBI images and anterior pinhole thyroid images for the localization of parathyroid adenomas in the neck in primary hyperparathyroidism. MethodsSixty-two patients underwent 99mTc-MIBI dual phase, anterior and anterior oblique pinhole images of the neck, anterior planar images of the neck and chest and early phase neck/chest SPECT followed by [99mTc] pertechnetate anterior and anterior oblique pinhole thyroid images. Images were reviewed by consensus in three combinations – dual phase anterior and anterior oblique pinhole 99mTc-MIBI images and pinhole thyroid images; SPECT and dual phase planar 99mTc-MIBI images and combined SPECT, dual phase planar 99mTc-MIBI images and anterior pinhole thyroid images. ResultsFor 52 parathyroid adenomas in 50 patients, the sensitivity of dual phase anterior and anterior oblique pinhole 99mTc-images and pinhole thyroid images was 81%. Significantly lower sensitivities were observed with SPECT and dual phase planar 99mTc-MIBI images (54%, P=0.0005) and combined SPECT, dual phase planar 99mTc-MIBI images and anterior pinhole thyroid images (65%, P=0.0209). The positive predictive value for all imaging combinations was 88–92%. ConclusionDual phase anterior and anterior oblique pinhole 99mTc-MIBI images and pinhole thyroid images are significantly more sensitive than imaging combinations that included SPECT and remains the optimal imaging protocol for the localization of parathyroid adenomas in the neck in primary hyperparathyroidism.

The youngest case of pervasive refusal syndrome

To date, the youngest previously recorded case of pervasive refusal syndrome (PRS) was eight years old. A four-year-old Australian-born Chinese boy presented to a tertiary paediatric referral centre with a four-week history of food refusal and selective mutism; he was severely dehydrated and marasmic. During admission several behavioural problems were noted including: persistent refusal to eat or drink, obsessions with images of food, failure to cooperate, lack of social interaction and toileting in inappropriate places. There were features of early maternal separation, concerns over the quality of parenting and confusion of language and culture. An exhaustive assessment (to exclude an organic explanation) by a multi- disciplinary team was completed. All investigations were normal with the exception of the single photon emission computerized tomography (SPECT) scan, which showed mild increase uptake to the right insular and mild decrease uptake to the right temporal region. He was hospitalized for 67 days over which time his medical difficulties resolved. The differential diagnosis included an organic disease, child abuse, an eating disorder, a degenerative disorder, reactive attachment disorder, pervasive developmental disorder and a psychotic disorder, which were all considered. We felt that this case fulfilled the diagnostic criteria for PRS and was the youngest reported case. The similarity of the SPECT scan result with that found in anorexia nervosa is of interest and suggests that there is a neurobiological vulnerability common to this group of disorders.

Optimal pinhole techniques for preoperative localization with Tc-99m MIBI for primary hyperparathyroidism.

Purpose Technetium-99m–labeled 2-methoxyisobutylisonitrile (Tc-99m MIBI) has been used extensively to localize parathyroid adenomas before operation. Imaging techniques vary widely, and the aim of this study was to determine the optimal time of delayed imaging and the value of routine correlative pertechnetate thyroid imaging. Materials and Methods In this study, preoperative parathyroid localization was performed using pinhole anterior and oblique images (15 minutes and 2 and 4 hours after injection) with correlative pertechnetate thyroid images. Ninety-seven patients underwent dual- or triple-phase Tc-99m MIBI imaging and correlative pertechnetate thyroid imaging before surgery. Two nuclear medicine physicians blinded to the surgical findings interpreted all available images and various Tc-99m MIBI image combinations at 15 minutes alone; 15 minutes and 2 hours, 15 minutes and 4 hours; and 15 minutes and 2 and 4 hours each with and without correlative pertechnetate thyroid imaging. Results Ninety parathyroid adenomas were detected in 86 patients. The optimal results were achieved with 15-minute and 2- and 4-hour Tc-99m-MIBI images, with correlative thyroid scans resulting in a sensitivity rate of 88%. Fifteen-minute and 2-hour Tc-99m-MIBI images and correlative thyroid scans and 15-minute and 4-hour Tc-99m MIBI images and correlative thyroid scans produced similar results (sensitivity rate, 86% and 83%, respectively;P = not significant). Compared with all Tc-99m MIBI image combinations alone, the addition of the routine correlative thyroid scan significantly improved sensitivity and also improved reporter confidence in 45% of studies. Conclusions Of the pinhole techniques compared, 15-minute and 2-hour Tc-99m MIBI images with correlative thyroid scanning may be the preferred imaging protocol, because this yields results similar to imaging for as long as 4 hours after injection in a shorter, more logistically acceptable imaging time.

Superimposed double parathyroid adenoma on Tc-99m MIBI imaging: the value of oblique images.

The authors present a case illustrating the Tc-99m MIBI scan appearances of superimposed double parathyroid adenoma (inferior parathyroid adenoma overlying a descended superior parathyroid adenoma). This case highlights some of the potential benefits of routine oblique imaging and the pitfalls of Tc-99m MIBI imaging in studies of multiple parathyroid adenomas.

Changing Therapeutic Paradigms: Predicting mCRC Lesion Response to Selective Internal Radionuclide Therapy (SIRT) based on Critical Absorbed Dose Thresholds: A Case Study

A 65 year old male with metastatic colorectal cancer (mCRC) in the liver was referred for selective internal radionuclide therapy (SIRT) following a history of extensive systemic chemotherapy. 90Y PET imaging was performed immediately after treatment and used to confirm lesion targeting and measure individual lesion absorbed doses. Lesion dosimetry was highly predictive of eventual response in the follow-up FDG PET performed 8 weeks after therapy. The derived radiation dose map was used to plan a second SIRT procedure aiming to protect healthy liver by keeping absorbed dose below the critical dose threshold, whilst targeting the remaining lesions that had received sub-critical dosing. Again, 90Y PET was performed immediately post-treatment and used to derive absorbed dose measures to both lesions and healthy parenchyma. Additional follow-up FDG PET imaging again confirmed the role of the 90Y PET dose map as an early predictor of response, and a tool for safe repeat treatment planning.

Dramatic response to selective internal radiation therapy for unresectable hepatocellular carcinoma

A 54-year-old woman with a known history of multifocal hepatocellular carcinoma was treated with selective internal radiation therapy (SIRT) using yttrium-90 (90Y) microspheres, despite disease relapses after surgical resection and transarterial chemoembolization. She developed a dramatic clinical, radiological and metabolic response after 9 weeks. This case provides visual illustration of the potential roles of SIRT in the treatment of hepatocellular carcinoma.