Retrospective Diagnosis of Ca Thyroid on Thyroid Pertechnetate Scan -A part of Routine Post Thyroidectomy Work up For Nontoxic Multi Nodular Goiter.

Unsuspected thyroid cancer can be detected in multinodular goiter (MNG) where the risk of malignancy is 7-9%. Fine needle aspiration (FNAc) is performed in case of suspicious findings on ultrasound. With benign FNAC results there is no need for surgery unless the patient has pressure symptoms or cosmetic concerns, but the risk of overlooked malignancy is always present. We present the case of a patient with unexpected detection of papillary thyroid cancer on thyroid scan.

Menstruation Confounding the Correct Interpretation of 99m Tc-RBC Bleeding Scan.

ABSTRACT: 99m Tc-RBC bleeding scan in a 17-year-old adolescent girl showed an increased focal activity in the pelvis. However, SPECT/CT showed that this activity was located in the uterus, which was considered a normal variant considering that the patient was in her fourth day of the menstrual period. Subsequent 99m TcO 4- Meckel scan showed the typical characteristic of ectopic gastric mucosa in the small bowel. Postsurgical pathology confirmed the diagnosis of ectopic gastric mucosa. This case suggested the menstrual period uterus should be included as differential diagnosis of 99m Tc-RBC scan.

Thyroid Accumulation of 99m Tc-DTPA in Graves Disease.

ABSTRACT: 99m Tc-DTPA dynamic renal scintigraphy for evaluating glomerular filtration rate was performed in a 29-year-old woman with hyperuricemia and Graves disease. Subsequently, 99m Tc-DTPA orbital scintigraphy was conducted to determine the activity of Graves ophthalmopathy. Thyroid accumulation of 99m Tc-DTPA was incidentally identified. This should be cautiously distinguished from 99m Tc-pertechnetate uptake, considering that the salivary glands, oral cavity, and stomach were not visualized. Our case demonstrates that augmentation of blood supply, enhancement of capillary permeability, and accumulation of inflammatory exudate may be involved in the pathological process of Graves disease.

Thyroid segmentation using perithyroidal halo layer on 99mTc-pertechnetate thyroid SPECT/CT: An easy and reliable method for accurate quantification of thyroid activity.

OBJECTIVE: In previous fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) studies, tumor segmentation using peritumoral halo layer (PHL; SegPHL) was shown to be reliable and accurate segmentation method in various malignant tumors. We found that the halo layer also was observed on the 99mTc-pertechnetate (99mTcO4) thyroid single photon emission computed tomography (SPECT)/CT. In the present study, we attempted to apply thyroid segmentation using the perithyroidal halo layer (PTHL; SegPTHL) on 99mTcO4 thyroid SPECT/CT and compared SegPTHL with CT-based thyroid segmentation (SegCT). SUBJECTS AND METHODS: A total of 33 patients (19 females, 14 males; mean age, 46.91±15.7 years old) were enrolled in this study. For SegCT, three-dimensional volume of interest (VOI) of the thyroid was generated via multiple 2-dimensional regions of interest (ROI) along the thyroid margin on transaxial CT images that were manually drawn slice by slice. The PTHL was easily identified by an abrupt increase in layer thickness with minimal or mild distortion of the main thyroid contour, and the thyroid margin for SegPTHL was determined at the innermost portion of PTHL. An automated VOI generation for SegPTHL was performed using the Q. Volumetrix software. The correlation and reliability tests were performed between the quantification parameters of SegPTHL and SegCT. RESULTS: The PTHL threshold adjusted according to maximal SUV of thyroid were similar to the results of previous SegPHLstudies of 18F-FDG PET/CT. A good correlation was observed between the thyroid volumes of SegCT and SegPTHL (r=0.725; P<0.0001), although the thyroid volume of SegPTHL was slightly larger than that of SegCT (P=0.0017). The % thyroid uptake (TcTU), total lesion activity (TLA), and mean standardized uptake value (SUVmean) of SegPTHL correlated well with those of SegCT (r=0.9877, 0.9883, 0.9875, respectively; P<0.0001). No significant error was observed between the parameters (i.e., TcTU, TLA, and SUVmean) of SegPTHL and SegCT. CONCLUSION: Thyroid segmentation PTHL may be a useful method for reliable quantification of thyroid uptake, because the SPECT/CT parameters of SegPTHL were strongly correlated with those of SegCT, as well as the process of SegPTHL is easier and faster than that of SegCT.

99mTc-pertechnetate thyroid static scintigraphy unexpectedly revealed ectopic gastric mucosa of upper esophagus.

Technetium-99m (99mTc)-pertechnetate can be taken up by both gastric mucosa and thyroid tissue. Ectopic gastric mucosa of upper esophagus found in thyroid scintigraphy is rare. We reported a 31-year-old woman who underwent 99mTc-pertechnetate thyroid static scintigraphy for abnormal ultrasound findings. A focal uptake lesion was found in her upper chest. Single photon emission computed tomography/computed tomography (SPECT/CT) imaging showed increased uptake in multiple sites of the upper esophagus without significant thickening. Eventually, gastroscopic findings revealed multiple ectopic gastric mucosa of upper esophagus.

Patient Preparation with Esomeprazole Is Comparable to Ranitidine in Meckel Diverticulum Scintigraphy.

To localize ectopic gastric mucosa in patients with unexplained gastrointestinal bleeding and diagnose a Meckel diverticulum, 99mTc-pertechnetate imaging is the standard procedure. H2 inhibitor pretreatment enhances the sensitivity of the scan by reducing washout of 99mTc activity from the intestinal lumen. We aim to provide evidence of the effectiveness of the proton pump inhibitor esomeprazole as an ideal substitute for ranitidine. Methods: The scan quality for 142 patients who underwent a Meckel scan during a period of 10 y was evaluated. The patients were pretreated with ranitidine orally or intravenously before a switch to a proton pump inhibitor after ranitidine was no longer available. Good scan quality was characterized by the absence of 99mTc-pertechnetate activity in the gastrointestinal lumen. The effectiveness of esomeprazole to diminish 99mTc-pertechnetate release was compared with the standard treatment using ranitidine. Results: Pretreatment with intravenous esomeprazole resulted in 48% of scans with no 99mTc-pertechnetate release, 17% with release either in the intestine or in the duodenum, and 35% with 99mTc-pertechnetate activity both in the intestine and in the duodenum. Evaluation of scans obtained after oral ranitidine and intravenous ranitidine showed absence of activity in both intestine and duodenum in 16% and 23% of the cases, respectively. The indicated time to administer esomeprazole before starting the scan procedure was 30 min, but a delay of 15 min did not negatively influence the scan quality. Conclusion: This study confirms that esomeprazole, 40 mg, when administered intravenously 30 min before a Meckel scan, enhances the scan quality comparably to ranitidine. This procedure can be incorporated into protocols.

Dosimetric evaluation of 123I (Iodide) and 99mTc (Pertechnetate) in the thyroid of neonates using Cristy-Eckerman and Segars anatomical representations.

Using the MIRD formalism, and the Cristy-Eckeman and Segars anthropomorphic representations, the absorbed dose in the thyroid of newborns, was calculated when 123I (iodide) and 99mTc (pertechnetate) are used during the diagnostic procedures. The dose results will allow exploring the dosimetric impact generated by the use of these radiopharmaceutical compounds and the use of two representations. Regardless the radiopharmaceutical compound and the anthropomorphic representation is the thyroid self-dose is the greatest, due to electrons emitted during the 123I and 99mTc radioisotopes. The relative difference in total dose to the newborn thyroid gland using the Cristy-Eckerman and Segars anthropomorphic representations for the compounds 123I(iodide) and 99mTc(pertechnetate) is 1.82%, and 1.33%, respectively. Regardless of the radiopharmaceutical compound, the replacement of Cristy-Eckerman by Segars phantom does not reflect significant changes in the estimated absorbed dose to the newborn thyroid. Regardless of the anthropomorphic representation, the lowest absorbed dose in newborn's thyroid is obtained when using 99mTc (pertechnetate) is used due to the residence times.

The Effectiveness of Ionized Water as a Radiodecontaminant for 99mTc-Pertechnetate and 131I.

Immediate and complete decontamination procedures are essential to restore the functionality, precision, accuracy, and safety of tests done within the nuclear medicine facility. Decontamination is a simple procedure that, if performed correctly, effectively reduces exposure brought about by spills. The determination of a suitable radiodecontaminant may be beneficial in decontaminating patient beds, collimators, probes, and machines. Methods: Two surface types (i.e., stainless steel and vinyl) were contaminated with a predetermined activity of 99mTcO4 and 131I. After air drying, static images of the contaminated surfaces were obtained using a γ-camera to determine the activity counts on each surface before and after decontamination procedures. Different decontaminant contact times (i.e., 5, 10, and 15 min) were used for each decontaminant (i.e., ionized water, 10% bleach, detergent solution, a negative control [no treatment], and a positive control [a commercial radiodecontaminant]). Differences between the effectiveness of ionized water and the other decontaminants against 99mTcO4 and 131I at different contact times were measured, and the mean percentage activity removed (%AR) was compared using 2-way ANOVA at the 0.05 level of significance. Results: 99mTcO4 and 131I contaminants had %ARs of greater than 80% after 5 min of contact time for ionized water and the other decontaminants. At 15 min contact time, ionized water was not as effective as the other decontaminating agents for 131I on vinyl surfaces. There was no significant interaction between the effects of the decontaminants (%AR) and the contact times with stainless steel and vinyl for either 99mTcO4 or 131I. Conclusion: For 99mTcO4 and 131I on stainless steel surfaces, ionized water is an effective decontaminant at contact times of 5, 10, and 15 min. For 99mTcO4 on vinyl surfaces, ionized water is also an effective decontaminant at contact times of 5, 10, and 15 min. For 131I on vinyl surfaces, ionized water is as effective as 10% bleach, detergent solution, and a commercial radiodecontaminant at contact times of 5 and 10 min.

Preoperative imaging for hyperparathyroidism often takes upper parathyroid adenomas for lower adenomas.

We retrospectively evaluated how accurately preoperative imaging localizes parathyroid adenoma in superior versus inferior parathyroids. Over 6 years, 104 patients with primary hyperparathyroidism underwent parathyroid surgery in a single centre. Of these, 103 underwent ultrasound, 97 [99mTc]pertechnetate/MIBI SPECT/CT and 30 [18F]fluorocholine (FCH) PET/CT. One patient with a unilateral double adenoma was excluded from the analysis. Surgical findings with histopathologic confirmation of adenoma were used as the standard. Ultrasound misjudged 5 of 48 detected lower adenomas as upper, but 14 of 29 upper adenomas as lower (error rate 10 vs 48%, p = 0.0002). The corresponding error rates for [99mTc]pertechnetate/MIBI SPECT/CT were 3 versus 55% (p = 0.000014), and for [18F]FCH PET/CT 17 versus 36% (p = 0.26). Our results suggest that about half of the superior parathyroid adenomas which are detected, are erroneously assigned to the inferior position by both ultrasound and SPECT/CT imaging whereas the opposite mistake is significantly less frequent with ultrasound and SPECT/CT.

99mTc-Pertechnetate in Diagnosis of Meckel Diverticulum in an Adult.

One of the most common malformations of the gastrointestinal tract is Meckel diverticulum (MD). MD complications can range from minor to major, such as intestinal obstruction, intussusception, hemorrhage, ulceration, vesicodiverticular fistulae, and tumors. Bleeding from ectopic gastric mucosa is more common in children than in adults. In the current case, MD in a 25-y-old man was diagnosed by 99mTc-pertechnetate scanning. 99mTc-pertechnetate scanning helps to diagnose MD noninvasively and has a potential role in the evaluation of MD even in adults.

Gastric Mucosal Viability Assessment Using 99mTcO4 in a Case of Pure Esophageal Atresia After Isoperistaltic Gastric Tube Replacement.

ABSTRACT: Gastric surface mucosal cells are responsible for the uptake and secretion of 99mTcO4, a feature that has been used in imaging heterotopic gastric mucosa. We used the same principle to look for gastric mucosal viability in this case of pure esophageal atresia admitted for cervical stomal closure after a previous isoperistaltic gastric tube (IGT) replacement procedure. 99mTcO4 scintigraphy was done after encountering a failure to maneuver the esophagoscope through the IGT. The study was helpful in assessing the loss of gastric mucosal viability in an intervening segment of the IGT.

The Removal of Pertechnetate from Aqueous Solution by Synthetic Hydroxyapatite: The Role of Reduction Reagents and Organic Ligands.

The use of knowledge from technetium radiochemistry (even from nuclear medicine applications) allows us to select an sorbent for 99mTc radionuclide sorption, which is hydroxyapatite. Using radioisotope indication, the 99mTcO4- sorption process on synthetic hydroxyapatite was studied by the batch method in the presence of SnCl2 and FeSO4 reducing agents. The complexing organic ligands' effect on the 99mTcO4- sorption under reducing conditions was investigated. In the presence of Sn2+ ions without the addition of organic ligand, the sorption percentage reached above 90% independently of the environment. In the presence of Fe2+ ions without the addition of organic ligand, the sorption of 99mTcO4- was significantly lower and was at approximately 6%, depending on the concentration of Fe2+ ions in solution. The effect of complexing organic ligands on the 99mTcO4- sorption on hydroxyapatite from the aqueous solution, acetate buffer and phosphate buffer decreases in the following order for Sn2+: oxalic acid > ethylenediaminetetraacetic acid > ascorbic acid. In the presence of Fe2+ ions without organic ligands, the sorption reached up to 15% depending on the composition of the solution. The addition of oxalic acid and ascorbic acid increased the sorption up to 80%. The ethylenediaminetetraacetic acid had no significant effect on the sorption of technetium on hydroxyapatite.

New Preparative Approach to Purer Technetium-99 Samples-Tetramethylammonium Pertechnetate: Deep Understanding and Application of Crystal Structure, Solubility, and Its Conversion to Technetium Zero Valent Matrix.

99Tc is one of the predominant fission products of 235U and an important component of nuclear industry wastes. The long half-life and specific activity of 99Tc (212,000 y, 0.63 GBq g-1) makes Tc a hazardous material. Two principal ways were proposed for its disposal, namely, long-term storage and transmutation. Conversion to metal-like technetium matrices is highly desirable for both cases and for the second one the reasonably high Tc purity was important too. Tetramethylammonium pertechnetate (TMAP) was proposed here as a prospective precursor for matrix manufacture. It provided with very high decontamination factors from actinides (that is imperative for transmutation) by means of recrystallisation and it was based on the precise data on TMAP solubility and thermodynamics accomplished in the temperature range of 3-68 °C. The structure of solid pertechnetates were re-estimated with precise X-ray structure solution and compared to its Re and Cl analogues and tetrabutylammonium analogue as well. Differential thermal and evolved gas analysis in a flow of Ar-5% H2 gas mixture showed that the major products of thermolysis were pure metallic technetium in solid matrix, trimethylammonium, carbon dioxide, and water in gas phase. High decontamination factors have been achieved when TMAP was used as an intermediate precursor for Tc.

Excreted 99m Tc-Pertechnetate in a Renal Pelvis as a Potential False Positive in a Meckel's Scan.

ABSTRACT: A 14-year-old girl presented with right lower quadrant pain. A 99m Tc-pertechnetate scan with SPECT/CT was performed to exclude a Meckel's diverticulum. The images demonstrated focal tracer uptake in the right midabdomen, which appeared early and decreased over time. However, SPECT/CT revealed that this uptake corresponded to the right renal pelvis, which was located more inferior than expected. This case emphasizes the importance of recognizing anatomic variants that may cause focal tracer uptake, as well as leveraging an understanding of tracer kinetics to inform a diagnosis.

The prognostic value of post thyroidectomy Tc-99m pertechnetate thyroid scan in patients with differentiated thyroid cancer.

AIM: To evaluate the prognostic value of postoperative Tc-99m pertechnetate scanning in patients with differentiated thyroid cancer (DTC). METHOD: Patients with pathologically proven low or intermediate-risk DTC were enrolled in this study. Postoperative Tc-99m pertechnetate scintigraphy was performed 20 min after IV of 185 MBq of Tc-99m pertechnetate Positive thyroid residual uptake was characterized as higher Tc-99m pertechnetate uptake at the thyroid bed than the surrounding background's activity. A negative residual was considered if there was no definite abnormal radioactivity at the thyroid bed. Follow-up by thyroglobulin, thyroglobulin antibodies (Tg Abs), neck ultrasound (US) and diagnostic I-131 WBS (Dx WBS) were considered the reference standard. Successful ablation outcome was considered if there was free Dx WBS, stimulated serum thyroglobulin < 1 ng/ml with negative Tg Abs, and free US. RESULT: Two hundred and two patients, mean age; of 38.8 years were retrospectively recruited in this study. Positive residual uptake at the thyroid scan was detected in 131 patients wherea the remaining 71 patients had no detectable uptake. According to the reference standard we encountered 114 and 88 cases with successful ablation and unsuccessful ablation respectively, Tc-99m pertechnetate scanning successfully detected 63 true positive and 46 true negative cases giving 72% sensitivity, 40% specificity, 48% positive predictive value and 56% negative predictive value. CONCLUSION: In low- and intermediate-risk DTC patients; despite the relatively high sensitivity of postoperative Tc-99m pertechnetate thyroid scan, it has low specificity and low negative predictive value so it cannot be used to predict the ablation outcome.

Multi-time point imaging in 99m Tc-pertechnetate scintigraphy of ectopic gastric mucosa in duplication cysts: value-added services.

OBJECTIVES: The aim of our study was to describe the scintigraphic patterns of 99m Tc-pertechnetate uptake in patients who were referred to the department of nuclear medicine for evaluating and diagnosing ectopic gastric mucosa in foregut and midgut duplication cysts. MATERIALS AND METHODS: This hospital-based, retrospective cum prospective research spans a period of 8 years from April 2014 to January 2022. Previous hospital medical records were analyzed and subsequently, a database was prepared which included the age, sex, clinical indication of a 99m Tc-pertechnetate scan, and the planar and SPECT-computed tomography (CT) imaging findings. Postoperative histopathological reports were available for 21 patients. Dynamic and planar static imaging was performed. We included SPECT-CT in suspected duplication cysts to increase the sensitivity and specificity which is a tradeoff for a small amount of additional radiation exposure. A total of 69 patients were subjected to a 99m Tc-pertechnetate scan for suspected foregut or midgut duplication cysts. All were subjected to dynamic planar and delayed static images up to 24 h or until focal uptake of radiotracer was noted which corroborated the anatomical findings, whichever was earlier. SPECT-CT was performed along with the planar study in 31 patients which confirmed the findings. Previously performed CT scans were used for anatomical correlation in the remaining ones. RESULTS: Duplication cysts were localized in a total of 28 patients (19 foregut duplication cysts and 12 small bowel duplications - 3 patients had dual duplication cysts, both foregut, and midgut). Forty-one patients had no scintigraphic evidence of ectopic gastric mucosa. Of these 69 patients, histopathological diagnosis was available for 21 patients (22 lesions). The report was concordant with the scan findings in 15 patients (16 lesions) and 6 patients showed discordance in histopathological diagnosis and scan findings. CONCLUSION: In conclusion, multi-time point imaging is the key to diagnosing ectopic gastric mucosa of various sizes and in various locations. An abnormal radiotracer uptake in dynamic sequences, even before the appearance of the stomach in the region of the small bowel is indicative of intestinal duplication, and delayed radiotracer visualization in the region of the thorax is characteristic of intrathoracic foregut duplication cyst.

Meckel diverticulum scintigraphy: technique, findings and diagnostic pitfalls.

Meckel diverticulum, the most common congenital anomaly of the gastrointestinal tract, results from the aberrant involution of the omphalomesenteric duct and accounts for more than 50% of unexplained lower gastrointestinal bleeding in the pediatric population. The most accurate imaging tool to identify a Meckel diverticulum containing ectopic gastric mucosa is the Technetium-99m pertechnetate Meckel scan, a scintigraphic study with a reported accuracy of 90% in the pediatric population. In addition to depicting a Meckel diverticulum with ectopic gastric mucosa, careful attention to the normal biodistribution of the radiotracer can lead to the identification of unexpected pathology with implications for patient management. This article serves to review the embryological origin and anatomical features of Meckel diverticulum, highlight the role of scintigraphy in evaluating Meckel diverticulum, and discuss the proper imaging technique when performing this test. We will focus on pitfalls that can lead to an erroneous diagnosis as well as incidental findings that can affect patient management.

Pitfalls of DualTracer 99m-Technetium (Tc) Pertechnetate and Sestamibi Scintigraphy before Parathyroidectomy: Between Primary-Hyperparathyroidism-Associated Parathyroid Tumour and Ectopic Thyroid Tissue.

Diagnosis of primary hyperparathyroidism (PHP) is based on blood assessments in terms of synchronous high calcium and PTH (parathormone), but further management, particularly parathyroid surgery that provides the disease cure in 95-99% of cases, requires an adequate localisation of the parathyroid tumour/tumours as the originating source, with ultrasound and 99m-Technetium (99m-Tc) sestamibi scintigraphy being the most widely used. We aimed to introduce an adult female case diagnosed with PHP displaying unexpected intra-operatory findings (ectopic thyroid tissue) in relation to concordant pre-operatory imaging modalities (ultrasound + dual-phase 99m-Tc pertechnetate and sestamibi scintigraphy + computed tomography) that indicated bilateral inferior parathyroid tumours. A sudden drop in PTH following the removal of the first tumour was the clue for performing an extemporaneous exam for the second mass that turned out to be non-malignant ectopic thyroid tissue. We overviewed some major aspects starting from this case in point: the potential pitfalls of pre-operatory imaging in PHP; the concordance/discordance of pre-parathyroidectomy localisation modalities; the need of using an additional intra-operatory procedure; and the clues of providing a distinction between pathological parathyroids and thyroid tissue. This was a case of adult PHP, whereas triple localisation methods were used before parathyroidectomy, showing concordant results; however, the second parathyroid adenoma was a false positive image and an ectopic thyroid tissue was confirmed. The pre-operatory index of suspicion was non-existent in this patient. Hybrid imaging modalities are most probably required if both thyroid and parathyroid anomalies are suspected, but, essentially, awareness of the potential pitfalls is mandatory from the endocrine and surgical perspectives. Current gaps in imaging knowledge to guide us in this area are expected to be solved by the significant progress in functional imaging modalities. However, the act of surgery, including the decision of a PTH assay or extemporaneous exam (as seen in our case), represents the key to a successful removal procedure. Moreover, many parathyroid surgeons may currently perform 4-gland exploration routinely, precisely to avoid the shortcomings of preoperative localisation.

[99m-Technetium-pertechnetate- and 99m-Technetium-sestamibi-scintigraphy for visualization of hypofunctioning thyroid tissue and staging in a dog with thyroid carcinoma]. / 99m-Technetium-Pertechnetat- und 99m-Technetium-Sestamibi-Szintigrafie zur Darstellung von hypofunktionellem Schilddrüsengewebe und Staging bei einem Hund mit Schilddrüsenkarzinom.

A 10-year-old female mixed breed dog was presented for thyroid scintigraphy due to a cervical mass. Apart from 99m-Technetium-pertechnetate (Tc-pertechnetate) scintigraphy, a second scintigraphy using 99m-Technetium sestamibi (Tc-MIBI) was performed because of additional hypothyroidism suspective for a "cold" nodule and as screening for metastases.Twenty minutes following intravenous injection of 38 MBq Tc-pertechnetate, a "hot" cervical as well as a "hot" intrathoracal nodule were seen with an uptake of 8.40 and 0.25 %, respectively. The second scintigraphy was performed 20 minutes after intravenous injection of 364 MBq Tc-MIBI and 70 minutes following the first. After subtraction of pertechnetate activity and decay correction, both nodules showed an uptake of 0.99 and 0.03 %. Additionally, both thyroid lobes were visible in the thyroid loge with a weak MIBI-uptake. For both lesions, the ratio Tc-uptake/Tc-MIBI-uptake was 8.48 and 8.33, respectively.Following the extirpation of the cervical mass, histopathology revealed atrophied healthy thyroid tissue almost completely displaced by a well-differentiated follicular thyroid carcinoma.This case report describes performance, utility and calculative correction of consecutive pertechnetate- and MIBI-scan, that enable a visualization of hypofunctional thyroid tissue.Therefore and because of their similar MIBI metabolic activity, both nodules were considered to be dystopic tissue/metastases so that this dog had to be classified as prognostically less favorable WHO stabe IV. Different from human patients, both scintigraphies should be performed shortly after another in dogs in order to avoid the necessity of a second anesthetic procedure. A reliable qualitative/visual evaluation of the MIBI-scan is therefore not possible, so that a quantitative assessment using the uptake after calculative correction of the pertechnetate activity is recommended.

The utility of technetium-99m pertechnetate thyroid scintigraphy assessing thyroid/salivary ratio as an alternative to thyroid uptake percentage in evaluation of thyroid function, with establishing normal reference values of both parameters: single Egyptian center study.

BACKGROUND/OBJECTIVE: Management of thyroid disorders depends on accurate clinical assessment, appropriate investigations and radionuclide imaging, which plays an established important role either qualitatively or quantitatively. The aim of this study was to assess the utility of the thyroid/salivary ratio (TSR) as an alternative to technetium-99m (Tc99m) pertechnetate thyroid uptake (TcU) percentage in the evaluation of thyroid function and in the same time to establish reference range for the thyroid uptake of Tc99m-pertechnetate and TSR among Egyptian populations. PATIENTS AND METHODS: This retrospective study enrolled 270 patients, out of which 250 with different thyroid disorders and 20 without thyroid diseases, as a control group who all underwent full clinical examination, thyroid function tests and Tc99m pertechnetate thyroid scintigraphy. The TcU percentage and TSR were calculated and then correlated to the thyroid hormonal profile. RESULTS: The normal reference ranges of TcU and TSR were 0.75-3.5% and 1.25-4.8%, respectively. The sensitivity and specificity of TSR to diagnose hyperthyroidism were slightly lower compared with TcU (84.5 and 92.3% vs. 86.2 and 98.3%, respectively) at TSR cutoff value of more than 4.8 and TcU cutoff value of more than 3.5. Meanwhile, they had comparable sensitivity and specificity to diagnose hypothyroidism (86.0 and 93.3% vs. 86.5 and 94.5%) at cutoff values <0.75 and <1.25, respectively. CONCLUSION: The current study established a reference range for TcU and TSR in our institution. TSR is comparable to TcU in the evaluation of thyroid function among hyper-and hypothyroid patients and TSR can be used in doubtful cases of mal-thyroid function for confirmation of the diagnosis.