Nuclear medicine in the diagnosis of benign thyroid diseases

Thyroid gland has the unique ability to concentrate iodine. Thisphenomenon offers a perfect background for a wide range ofdiagnostic tests utilizing radioactive iodine nuclides of iodineand technetium. Despite the very good availability of ultrasonographyand other imaging modalities, radionuclide methodsare still inevitable in a various cases of thyroid disease. In thisarticle, a comprehensive review of all these methods used inthe diagnosis of benign thyroid diseases is presented. Iodineand technetium uptake tests are briefly described. Indications tothyroid scan in the context of iodine supply are also presented.Finally, the significance of thyroid findings in PET images ispointed out. The article is illustrated by some typical patternsof radionuclide thyroid images.Thyroid gland has the unique ability to concentrate iodine. Thisphenomenon offers a perfect background for a wide range ofdiagnostic tests utilizing radioactive iodine nuclides of iodineand technetium. Despite the very good availability of ultrasonographyand other imaging modalities, radionuclide methodsare still inevitable in a various cases of thyroid disease. In thisarticle, a comprehensive review of all these methods used inthe diagnosis of benign thyroid diseases is presented. Iodineand technetium uptake tests are briefly described. Indications tothyroid scan in the context of iodine supply are also presented.Finally, the significance of thyroid findings in PET images ispointed out. The article is illustrated by some typical patternsof radionuclide thyroid images

99mTc-EDDA/HYNIC-TOC in the diagnosis of differentiated thyroid carcinoma refractory to radioiodine treatment

BACKGROUND: In majority of cases of differentiated thyroid carcinoma (DTC), the ablative radioiodine treatment shows high efficacy. In a small number of patients, mechanism of selective iodine uptake by the DTC cells is insufficient and alternative methods of diagnosis and treatment are needed. As demonstrated in vitro, DTC cells show expression of somatostatin recep­tors. Radiolabeled somatostatin analogs are widely used in the diagnosis of neuroendocrine tumors. The aim of the study was to evaluate the utility of peptide receptor scintigraphy with the use of 99mTc-EDDA/HYNIC-TOC in the diagnosis of DTC in patients with elevated thyroglobulin concentrations (Tg), negative WBS and no effect of the consecutive radioiodine therapies. MATERIAL AND METHODS: Whole body scintigraphy as well as SPECT of neck and chest were performed 3 and 24 h after i.v. administration of 740 MBq 99mTc-EDDA/HYNIC-TOC. The obtained images were compared with other radionuclide and ra­diological imaging methods. Forty-three patients with DTC after surgery and ablative radioiodine treatment with negative WBS and elevated Tg were qualified. Patients’ age: 18–83 years (mean 58.0). RESULTS: SRS showed foci of tracer accumulation in 29 cases (67.4%). Sensitivity was 69.0% specificity 78.6%. SRS correctly identified local recurrence in 8 pts., metastatic lymph nodes in 19 pts., lung metastases in 12 pts. and bone metastases in 5 pts. SRS showed high sensitivity in the detection of metastatic lymph nodes (100%) and bone metastases (83.3%) and lung metastases (63.2%). Positive SRS was found in pts. with higher Tg concentrations (130 ± 144 vs. 30 ± 54 ng/ml). CONCLUSION: Scintigraphy with the use of the studied technetium-99m-labeled somatostatin analog is useful in the evaluation of patients with advanced DTC. It shows relatively good sensitivity and specificity but not high enough to be recommended as a routine imaging method. The role of somatostatin receptor scintigraphy in DTC is complementary to other imaging modalities

False-positive radioiodine whole-body scan due to a renal cyst

Patients affected by differentiated thyroid cancer are treated surgically and by ablative radioiodine therapy. A post-therapy whole-body scan allows detection of thyroid remnants or local and distant metastases, although false-positive findings may be observed. We report a case of a 75-year-old woman with follicular thyroid cancer, who underwent ablative radioiodine treatment. On post-therapy wholebody scan, abnormal uptake in the left upper abdomen was found, although stimulated thyroglobulin level was not suggestive for distant metastases of differentiated thyroid carcinoma. Additional SPECT/CT acquisition revealed focal 131I uptake located at the posterolateral wall of the left kidney corresponding to a round lesion 47 mm in maximal diameter. In order to verify this finding abdominal ultrasound and abdominal contrast-enhanced CT were performed, confirming multiple renal cysts in the left kidney; the largest one was the site of abnormal radioiodine accumulation. Despite the high incidence of renal cysts, especially in the elderly, radioiodine uptake in renal cystsis extremely rare. Different hypotheses on the mechanism of radioiodine uptake in the cyst were proposed, among them active secretion by sodium-iodide symporter or other transporting proteins. We conclude that abnormal radioiodine uptake in renal cysts can be an exceptional finding mimicking a metastasis

Increased uptake of technetium-99m methylene diphosphonate in muscles in the course of polymyositis

A case of a woman aged 46 years with signs of rhabdomyolysis and acute renal failure is presented. Coxsackie serum test was positive. Increased uptake of Technetium-99m methylene diphosphonate (99mTc-MDP) by muscles of thighs and calves was observed. After 1 year no increased accumulation of radiotracer in the muscles was found

PET/MR — a rapidly growing technique of imaging in oncology and neurology

INTRODUCTION: The combination of positron emission tomography (PET) and magnetic resonance (MR) has become a subject of interest for researchers in the recent several years. Positron emission tomography in combination with magnetic resonance (PET/MR) is the most recent imaging technique classified in the so called hybrid systems category. AIM: This review briefly discusses the development history of PET/MR scanners, the principle of their operation, of tandem systems, as well as fully integrated devices. Further, it summarizes recent reports on the application of PET/MR scans and their possible future role in oncological and non-oncological diagnostics. CONCLUSIONS: Recent reports regarding the application of PET/MR scanners show huge potential of simultaneously received images, which exceed the advantages of either of those scans used separately. However, the results so far remain uncertain and require further investigations, especially in terms of clinical studies, not only for scientific purposes.      INTRODUCTION: The combination of positron emission tomography (PET) and magnetic resonance (MR) has become a subject of interest for researchers in the recent several years. Positron emission tomography in combination with magnetic resonance (PET/MR) is the most recent imaging technique classified in the so called hybrid systems category. AIM: This review briefly discusses the development history of PET/MR scanners, the principle of their operation, of tandem systems, as well as fully integrated devices. Further, it summarizes recent reports on the application of PET/MR scans and their possible future role in oncological and non-oncological diagnostics. CONCLUSIONS: Recent reports regarding the application of PET/MR scanners show huge potential of simultaneously received images, which exceed the advantages of either of those scans used separately. However, the results so far remain uncertain and require further investigations, especially in terms of clinical studies, not only for scientific purposes

Przerzut do móżdżku raka brodawkowatego tarczycy wykryty w scyntygrafii receptorów somatostatynowych

Introduction: Distant metastases of papillary thyroid carcinoma (PTC) may lack the ability to concentrate radioiodine. In such cases, positive somatostatin receptor scintigraphy might be useful in demonstrating the expression of somatostatin receptors that are potential therapeutic targets. To date, only a few cerebellar metastases from PTC have been reported in the literature. Patient findings: We present an 82-year-old female, in whom an asymptomatic cerebellar metastasis from PTC was diagnosed by means of Tc-99m-EDDA/HYNIC-TOC scintigraphy four years after the initial diagnosis. She was previously treated with total thyroidectomy and regional lymph node dissection, followed by three cycles of radioiodine therapy. Despite persistently elevated thyroglobulin, no specific radioiodine accumulation was found in the whole body post-treatment scan. Tc-99m-EDDA/HYNIC-TOC scintiscan revealed foci of increased tracer uptake in the lungs, cervical lymph nodes, and a single focus in the head. Thus, therapy with octreotide LAR was initiated. The patient died four months later due to disseminated PTC. Summary: In this paper, a patient with asymptomatic previously unknown non-iodine avid cerebellar metastasis of PTC diagnosed by means of scintigraphy using somatostatin analogue Tc-99m-EDDA/HYNIC-TOC is reported. Conclusions: Somatostatin receptor scintigraphy might be useful in the visualisation of non-iodine avid PTC metastases and demonstrat­ing the expression of somatostatin receptors that are potential therapeutic targets.Wstęp: Odległe przerzuty raka brodawkowatego tarczycy (papillary thyroid carcinoma, PTC) mogą nie wykazywać zdolności do gromadzenia radiojodu. W takich przypadkach użytecznym badaniem może być scyntygrafia receptorów somatostatynowych, która może wykazać ekspresję receptorów somatostatyny będących potencjalnym celem terapeutycznym. Dotychczas opisano zaledwie kilka przypadków przerzutów PTC do móżdżku. Opis przypadku: U pacjentki w wieku 82 lat cztery lata po ustaleniu wstępnej diagnozy wykryto bezobjawowy przerzut PTC do móżdżku za pomocą badania scyntygraficznego z użyciem znacznika Tc-99m-EDDA/HYNIC-TOC. Wcześniejsze leczenie chorej obejmowało całkowitą tyroidektomię z resekcją regionalnych węzłów chłonnych, po której zastosowano trzy cykle radioterapii. Mimo stale podwyższo­nego stężenia tyreoglobuliny nie stwierdzono miejscowego gromadzenia radiojodu w scyntygrafii całego ciała wykonanej po leczeniu. Przeprowadzone później badanie scyntygraficzne z użyciem Tc-99m-EDDA/HYNIC-TOC wykazało ogniska zwiększonego wychwytu znacznika w płucach i węzłach chłonnych szyi, a także pojedyncze ognisko w móżdżku. W związku z wynikiem badania rozpoczęto leczenie oktreotydem LAR. Chora zmarła cztery miesiące później z powodu rozsianego PTC. Podsumowanie: W tej pracy opisano przypadek chorej z bezobjawowym, niewykrytym wcześniej niejodochwytnym przerzutem do móżdżku raka brodawkowatego tarczycy, który został rozpoznany za pomocą badania scyntygraficznego z użyciem analogu somatostatyny Tc-99m-EDDA/HYNIC-TOC. Wnioski: Scyntygrafia receptorów somatostatynowych może być użyteczna do wizualizacji niejodochwytnych przerzutów PTC i wykrywania ekspresji receptorów somatostatynowych, które są potencjalnym celem terapeutycznym

Pozytonowa tomografia emisyjna (PET) w nowotworach złośliwych jajnika

Accessibility of positron emission tomography integrated with computed tomography (PET/CT) has improved significantly in recent years. PET/CT with the use of 18F-deoxyglucose (FDG) is widely used in patients with ovarian malignancies at different stages of the management. FDG PET/CT shows high diagnostic accuracy in the differentiation of benign and malignant ovarian lesions with the exception of borderline tumors that may cause false negative results. Moreover, FDG PET/CT is used in some centers for preoperative staging and determining the prognosis of ovarian cancer. However, further studies including larger groups of patients are needed to confirm the applicability of FDG PET/CT in case of the two abovementioned indications. Until now, the best documented indication for FDG PET/CT in patients with ovarian cancer has been the detection of recurrence, especially in subjects with elevated CA125 marker and negative results of other imaging techniques. This review focuses on the applicability of PET with the use of FDG in ovarian malignancies and points out to theW ostatnich latach znacznie wzrosła dostępność do pozytonowej tomografii emisyjnej sprzężonej z tomografią komputerową (PET/CT). PET/CT z użyciem 18F-deoksyglukozy (FDG) znajduje szerokie zastosowanie w nowotworach złośliwych jajnika na różnych etapach postępowania. FDG PET/CT wykazuje wysoki poziom dokładności diagnostycznej w różnicowaniu zmian łagodnych i złośliwych jajnika, przy czym w przypadku guzów o złośliwości granicznej obserwuje się wysoki odsetek wyników fałszywie ujemnych. Ponadto FDG PET/CT jest stosowana w niektórych ośrodkach w przedoperacyjnym stopniowaniu zaawansowania klinicznego raka jajnika oraz w określaniu rokowania u chorych na ten nowotwór, jednak dalsze badania na większych grupach pacjentek są konieczne do potwierdzenia użyteczności FDG PET/CT w tych dwóch wskazaniach. Dotychczas najlepiej udokumentowanym wskazaniem do badania FDG PET/CT jest ocena wznowy raka jajnika po leczeniu operacyjnym i chemioterapii, zwłaszcza w przypadku podwyższonych wartości CA 125 i negatywnego wyniku innych badań obrazowych. W niniejszym artykule dokonano przeglądu zastosowań PET z użyciem FDG w nowotworach złośliwych jajnika oraz zwrócono uwagę na ograniczenia tej metody

Incidental 18F-FDG uptake in the thyroid in patients diagnosed with PET/CT for other malignancies

BACKGROUND: The value of PET/CT imaging in diagnosis of different cancers has been widely described. PET/CT may contribute to visualization of additional findings that were not the indication to the study and did not refer to initial diagnosis. In a small number of PET/CT scans an incidentally found focal 18F-FDG uptake in the thyroid gland is found. The goal of the study was to estimate the prevalence and evaluate the clinical significance of incidental thyroid 18F-FDG uptake in a cohort of patients diagnosed for different malignancies. MATERIAL AND METHODS: 2478 PET/CT scans using 18F-FDG were performed in 1925 subjects for evaluation of different, non-thyroid malignancies. For PET/CT examination, a Discovery ST (General Electric) PET/CT scanner was used. Patients with focal 18F-FDG activity were further evaluated by means of fine needle aspiration biopsy (FNAB). If cytological examination disclosed malignancy or suspicion of malignancy, thyroidectomy was performed. Both cytological and histopathological results were then analyzed. RESULTS: Focal increased 18F-FDG uptake was found in 71 patients (3.7%), and cytological or histopathological results were evaluable in 20 of them. In general, 8 cases of thyroid cancer were found, which accounts for 40% probability of malignancy. The predominant histopathological diagnosis was papillary thyroid carcinoma (5 out of 8 cases). Additionally, in one case (5%) thyroid metastasis of lung cancer was detected. Diffused 18F-FDG activity in both thyroid lobes was observed in 120 subjects (6.2%) — in most cases chronic thyroiditis was confirmed. CONCLUSIONS: The probability of malignancy of focal thyroid incidentalomas in 18F-FDG PET/CT scans is rather high. Therefore, thorough evaluation of such lesions is highly recommended in each case. Most thyroid malignancies incidentally detected in PET/CT are papillary carcinomas. Nuclear Med Rev 2011; 14, 2: 68–7