Michael Gabriel

CT-MIBI image fusion: a new preoperative localization technique for primary, recurrent, and persistent hyperparathyroidism.

BACKGROUNDnSuccessful minimally invasive or imaging-guided operations in patients with primary, recurrent, and persistent hyperparathyroidism are based on the reliability of preoperative parathyroid localization studies. The CT-MIBI image fusion promises a higher diagnostic accuracy than current imaging procedures. The aim of our study was to assess its reliability in correctly detecting enlarged parathyroid glands.nnnMETHODSnIn a prospective study 24 consecutive patients underwent CT-MIBI image fusion as preoperative parathyroid localization procedure. The results of technetium 99m sestamibi single photon emission computed tomography (MIBI-SPECT) alone, today the standard method in parathyroid imaging, and CT-MIBI image fusion were analyzed by a blinded reviewer, and the imaging results were compared with the intraoperative findings.nnnRESULTSnFor CT-MIBI image fusion a sensitivity of 93% and a specificity of 100% in correctly detecting the position of enlarged parathyroid glands was calculated and compared with a sensitivity of MIBI-SPECT of 31% and a specificity of 87% (P<.001). This new imaging technique enabled us to successfully treat 22 of our patients (92%) with imaging-guided surgery. Twenty (83%) underwent unilateral or minimally invasive operations.nnnCONCLUSIONSnCT-MIBI image fusion appears to be superior to MIBI-SPECT in preoperative parathyroid imaging. CT-MIBI image fusion can be performed on existing CT- and MIBI-SPECT units. We recommend this method for preoperative localization in patients with primary, recurrent and persistent hyperparathyroidism.

99mTc-EDDA/HYNIC-TOC and 18F-FDG in thyroid cancer patients with negative 131I whole-body scans

Several studies have reported on the expression of somatostatin receptors in patients with differentiated thyroid cancer (DTC). The aim of this study was to evaluate the imaging abilities of a recently developed technetium-99m labelled somatostatin analogue, 99mTc-EDDA/HYNIC-TOC (99mTc-TOC), in terms of precise localisation of disease. The study population comprised 54 patients (24 men, 30 women; age range 22–90 years) with histologically confirmed DTC who presented with recurrent or persistent disease as indicated by elevated Tg levels after initial treatment. All patients were negative on the iodine-131 post-therapy whole-body scans. Fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) was performed in a subgroup of 36 patients. The study population consisted of two groups: Group A (n=22) comprised patients with disease recurrence as shown by elevated Tg levels but without detectable pathology. In group B (n=32), pre-existing lesions were known. Among the 54 cases, SSTR scintigraphy was true positive in 33 (61.1%), true negative in 4 (7.4%) and false negative in 17 (31.5%) cases, which resulted in a sensitivity of 66%. A total of 138 tumour foci were localised in 33 patients. The fraction of true positive 99mTc-TOC findings was positively correlated (P<0.01) with elevated Tg levels (higher than 30xa0ng/ml). Despite two false positive findings, analysis on a lesion basis demonstrated better diagnostic efficacy with 18F-FDG PET (P<0.001); however, it also revealed substantial agreement between the imaging techniques [Cohen’s kappa of 0.62 (0.47–0.78)]. In conclusion, scintigraphy with 99mTc-TOC might be a promising tool for treatment planning; it is easy to perform and showed sufficient accuracy for localisation diagnostics in thyroid cancer patients with recurrent or metastatic disease.

Image fusion analysis of 99m Tc-HYNIC-octreotide scintigraphy and CT/MRI in patients with thyroid-associated orbitopathy: the importance of the lacrimal gland

The aim of this study was to describe the anatomical structures that show uptake of the somatostatin analogue octreotide in patients with thyroid-associated orbitopathy (TAO). The study population comprised a series of 20 TAO patients attending the out-patient thyroid clinic and 12 patients presenting head or neck tumours. Scintigraphy was carried out with our newly developed tracer, technetium-99m labelled EDDA-HYNIC-TOC (99mTc-TOC). Morphological imaging was done with either magnetic resonance imaging or X-ray computed tomography without contrast medium. Both imaging procedures were done within an interval of 3–4 weeks. For the image fusion procedure, specific external reference markers were used for each imaging modality. The markers were screwed onto a reference frame, which was held in place via a vacuum-fixed mouthpiece. The anatomical structure showing tracer uptake that was most frequently recognised was the lacrimal gland, followed by the retronasal area, cervical lymph structures, salivary glands, the anterior insertion points of the extra-ocular muscles and discrete areas of the neck extensor muscles. The lacrimal gland and the retronasal area showed the highest and most frequent uptake of 99mTc-TOC in TAO patients, whereas such uptake did not occur in the retrobulbar space. In spite of knowledge of these results of image fusion, no changes in the involved structures could be detected on morphological imaging. It is concluded that binding of 99mTc-TOC is more frequently localised to the anterior compartment of the eye and to the neck. The previously used term orbital uptake should be abandoned and replaced by a descriptive term relating to the anatomically recognised structure showing tracer accumulation, i.e. the lacrimal gland. The uptake of octreotide by lymphoid and salivary glands opens a new field of investigation related to the physiology of somatostatin.

Accuracy of Preoperative Pinhole Subtraction Single Photon Emission Computed Tomography for Patients with Primary and Recurrent Hyperparathyroidism in an Endemic Goiter Area

PurposeBilateral parathyroid exploration is still the standard therapeutic procedure for primary and recurrent hyperparathyroidism (HPTH). Since a unilateral surgical strategy that reduces surgical complications should not increase the risk of missing enlarged parathyroid glands, reliable preoperative imaging is the first requirement for this approach. This study was conducted to assess the accuracy of preoperative 99mTcO4-201T1 pinhole subtraction single photon emission computed tomography (SPECT) compared with sonography.MethodsThe study population consisted of 15 patients with primary (n = 13) or recurrent (n = 2) HPTH who underwent preoperative 99mTcO4-201T1 pinhole subtraction SPECT. Preoperative sonography was also done in 14 of these patients.Results99mTcO4-201T1 pinhole subtraction SPECT was significantly more accurate than sonography. It had an overall accuracy of 80% in detection of enlarged parathyroid glands. The accuracy of localization increased to 92.3% in patients with solitary adenomas, and to 100% in those with solitary adenomas and no previous parathyroid exploration.ConclusionsThe high accuracy of preoperative localization with 99mTcO4-201T1 pinhole subtraction SPECT in patients with primary and recurrent HPTH allows for an imaging-guided unilateral operative strategy in most patients, even those with concomitant nodular goiters. This may reduce the risk of surgical complications and expand the use of minimally invasive techniques in parathyroid surgery.

Somatostatin receptor scintigraphy using 99mTc-EDDA/HYNIC-TOC in Graves’ disease

Decristoforo C, Mather SJ, Cholewinski W, Donnemiller E, Riccabona G, Moncayo R. 99mTc-EDDA/HYNIC-TOC: a new 99mTc-labelled radiopharmaceutical for imaging somatostatin receptor-positive tumours; first clinical results and intra-patient comparison with 111In-labelled octreotide derivatives. Eur J Nucl Med 2000; 27:1318-1325. Becker W, Schrell U, Buchfelder M, Hensen J, Wendler J, Gramatzki M, Wolf F. Somatostatin receptor expression in the thyroid demonstrated with 111In-octreotide scintigraphy. Nuklearmedizin 1995; 34:100-103. Moncayo R, Baldissera I, Decristoforo C, Kendler D, Donnemiller E. Evaluation of immunological mechanisms mediating thyroidassociated ophthalmopathy by radionuclide imaging using the somatostatin analog 111In-octreotide. Thyroid 1997; 7:2129.

99mTc-EDDA/HYNIC-TOC scintigraphy in oncological diagnostics: methodological considerations

We read with great interest the Short Communication from Anna Płachcińska et al. presenting their clinical experiences with 99mTc-EDDA/HYNIC-TOC [1]. In their pilot study a variety of tumour entities were included. The use of this tracer for diagnosis showed promising results. These results are in accordance with findings of a prospective investigation by our group [2]. One difference between the two publications lies in the number of patient studies performed to investigate tumours in the gastroenteropancreatic tract. This issue is worth addressing, considering that diagnosis of neuro-endocrine gastroenteropancreatic tumours might represent the vast majority of clinical investigations using somatostatin receptor scintigraphy. It is worth pointing out that 99mTc-EDDA/HYNIC-TOC seems to be superior to other 99mTc-labelled compounds, such as 99mTc-depreotide [3], for this indication. The better imaging properties in the abdomen and the liver are based on the imaging characteristics of the radiopharmaceutical, but also need an optimal acquisition protocol. According to our initial pilot study, the best tumour to non-tumour contrast was identified at 4 h post injection [4]. In the study by Płachcińska et al., imaging was started as early as 2 h after injection, which seems appropriate in terms of patient convenience and might be sufficient for scanning of regions in which lower unspecific background activity can be expected, e.g. the chest. In our opinion, however, such early imaging in the bowel should only be applied if later imaging is performed to avoid false positive findings due to non-specific uptake [2]. We congratulate the authors on this pilot study, which again shows that 99mTc-EDDA/HYNIC-TOC might be a useful radiopharmaceutical for oncological diagnostics. An optimised acquisition protocol should be used in order to obtain the best results which 99mTc-EDDA/ HYNIC-TOC can provide, enabling it to become an alternative to Octreoscan.

Methodological considerations influence the clinical value of parathyroid localisation diagnostics

1. Nishiyama Y, Yamamoto Y, Ono Y et al. Comparative evaluation of 99mTc-MIBI and 99mTc-HMDP scintimammography for the diagnosis of breast cancer and its axillary metastases. Eur J Nucl Med 2001; 28:522–528. 2. Kopans DB. The positive predictive value of mammography. Am J Rontgenol 1992; 158:521–526. 3. Khalkhali I, Mena I, Jouanne E, et al. Prone scintimammography in patients with suspicion of breast cancer. Am J Coll Surg 1994; 178:491–497. 4. Mirzaei S, Zajicek SM, Knoll P, et al. Scintimammography enhances negative predictive value of non-invasive pre-operative assessment of breast lesions. Eur J Surg Oncol 2000; 26: 738–741