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Lung scintigraphy is primarily used to diagnose pulmonary embolism. Ventilation imaging is often performed using (99m)Tc-DTPA or Technegas, an ultrafine dispersion of (99m)Tc-labeled carbon. Despite the common use of these radioaerosols, they have not been compared in an intraindividual study, and not with ventilation-perfusion (V/P) SPECT. The aim of the present head-to-head study was to systematically investigate differences in ventilation studies performed with (99m)Tc-diethylenetriaminepentaacetate (DTPA) and Technegas. Sixty-three patients, 28 without and 35 with obstructive lung disease, were examined with V/P SPECT using both (99m)Tc-DTPA and Technegas. V/P SPECT images were randomized and assessed independently by 2 masked physicians according to a predefined scoring system. A paired comparison was performed using the Wilcoxon signed-rank test. In both obstructive and nonobstructive disease, the overall unevenness of radiotracer deposition and the degree of central deposition were more pronounced in (99m)Tc-DTPA than Technegas studies. Because of better peripheral penetration, the extent of reverse mismatch was less when Technegas was used. Additionally, in obstructive disease, the degree of focal deposition in distal airways was more pronounced with (99m)Tc-DTPA. Mismatched perfusion defects were more frequently found with Technegas in obstructive disease. This intraindividual comparative study shows that Technegas is the preferred radioaerosol, particularly in obstructive disease.

ABSTRACT Purpose To determine distribution and deposition of Technosphere ® Insulin (TI) inhalation powder and the rate of clearance of fumaryl diketopiperazine (FDKP; major component of Technosphere particles) and insulin from the lungs. Methods Deposition and distribution of 99m pertechnetate adsorbed onto TI immediately after administration using the MedTone® inhaler was quantified by gamma-scintigraphy. Clearance from the lungs was studied in a second experiment by serial bronchoalveolar lavage (BAL) after administration of TI inhalation powder and assay of the recovered fluid for FDKP and insulin. Results Following inhalation, ~60% of radioactivity (adsorbed on TI) emitted from the inhaler was delivered to the lungs; the remainder of the emitted dose was swallowed. Clearance from the lung epithelial lining fluid (ELF) of FDKP and insulin have a half-life of ~1 hour. Conclusion TI inhalation powder administered via the MedTone inhaler was uniformly distributed throughout the lungs; ~40% of the initial cartridge load reached the lungs. Insulin and FDKP are quickly cleared from the lungs, mainly by absorption into the systemic circulation. The terminal clearance half-life from the lung ELF, estimated from sequential BAL fluid measurements for both components, was ~1 hour. Since there is an overnight washout period, the potential for accumulation on chronic administration is minimal.

Although ventilation/perfusion (V/Q) lung scintigraphy is a well-accepted and frequently performed procedure in the diagnosis of pulmonary embolism, there is growing controversy about its relevance, particularly due to the increasing competition between scintigraphy and CT. Even though comparative studies between both modalities have already been performed, their results were highly inconsistent. Remarkably, in most of those studies, conventional planar perfusion scans were compared with tomographic images acquired using state-of-the-art CT scanners-a study design that cannot give impartial results. Hence, the aim of our study was a balanced comparison between V/Q lung scintigraphy and CT angiography using advanced imaging techniques for both modalities. A total of 83 patients with suspected pulmonary embolism were examined using V/Q lung scintigraphy in SPECT technique as well as 4-slice spiral CT. Ventilation scans were done using an ultrafine aerosol. Additionally, planar images in 8 views were extracted from the V/Q SPECT datasets. Two experienced referees assessed each of the 3 modalities. The final diagnosis was made at a consensus meeting while taking into account all of the imaging modalities, laboratory tests, clinical data, and evaluation of a follow-up period. In the course of the consensus conference, pulmonary embolism was diagnosed in 37 of the 83 patients (44.6%). Compared with planar scintigraphy, SPECT raised the number of detectable defects at the segmental level by 12.8% (+11 defects; P = 0.401) and at the subsegmental level by 82.6% (+57 defects; P < 0.01). The sensitivity/specificity/accuracy of planar V/Q scintigraphy and V/Q SPECT was 0.76/0.85/0.81 and 0.97/0.91/0.94, respectively, compared with 0.86/0.98/0.93 for multislice CT. SPECT and ultrafine aerosols are technical advancements that can substantially improve lung scintigraphy. Using advanced imaging techniques, V/Q scintigraphy and multislice spiral CT both yield an excellent and, in all aspects, comparable diagnostic accuracy, with CT leading in specificity while SPECT shows a superior sensitivity. Even though planar lung scintigraphy yields satisfactory results for a nontomographic modality, it does not compare with tomographic imaging.

Aim/introduction In central Europe, up to 76% of population exhibit thyroid nodules (TN). The combination of ultrasound findings and thyroid scan imaging are supposed to ensure a cost-effective and reliable prediction of malignancy risk. However, real-world impact of ultrasound findings, i.e. TI-RADS, has raised concerns due to its highly limited reliability and reproducibility. The recent advancements and increasing access of SPECT/CT scanners might contribute to thyroid management. This study aimed to elucidate additive value of SPECT(-CT) imaging in initial evaluation of complex TN cases, particularly on multinodular goiter and difficult-to-characterize solitary nodules. Materials and methods A total of 61 patients (19 males and 42 females with a mean age of 56 (± 17)) with incidental TN were retrospectively enrolled in this study between November 2022 and July 2023, who underwent both conventional planar thyroid scan and SPECT(-CT) imaging. Three readers with varying experience level selected a target nodule within thyroid gland and evaluated its functionality, ACR TI-RADS categorization and additive benefit of SPECT(-/CT) imaging. Kappa-value for inter-reader agreement (IRA) was interpreted as follows: < 0.01–0.20, slight agreement; 0.21–0.40, fair agreement; 0.41–0.60, moderate agreement; 0.61–0.80, substantial agreement; and 0.81–1.00; almost perfect agreement. Results Of the target TNs, 33 (54%) were located in the left thyroid lobe, 5 (8%) in the isthmus and the remaining target TNs (38%) in the right lobe. The median target TN size was 20 mm (10–59). The target nodule match rate among readers was almost perfect (k-value 0.81; 95% CI: 0.72–0.90). The IRA regarding ACR TI-RADS was moderate with k-value of 0.47 (95% CI: 0.40–0.54). The IRA regarding patient referral was substantial among readers with k-value of 0.60, while k-value was even higher at pairwise comparison of experienced readers (k-value: 0.64). IRA regarding the target TN functionality among readers was good with k-value of 0.68 (95%CI: 0.59–0.77). IRA involving the less experienced reader revealed only slightly lower reliability scores, i.e. a k-value of 0.61. The correlation with ground truth results revealed comparable results among experienced and less-experienced readers. Conclusion Increasing clinical experience of physicians appeared to have a direct correlation with a higher referral rate of SPECT(-CT) imaging, although the additive clinical benefit was only evident for a minority of patients. Hence, SPECT(-CT) imaging might be more suitable for tertiary care centers, as its additive benefit at primary care level would have only negligible effect for patients.

Abstract Purpose The effect of methimazole withdrawal period (MWP) on the estimation of 24-hour-radioiodine thyroid uptake (131IU24h) from 99mTc-pertechnetate thyroid uptake (99mTcTU) remains unclear for patients with Graves’ disease (GD). This study aims to investigate the feasibility and reliability of 99mTcTU-based 131IU24h estimation with different MWPs. Methods We enrolled 116 GD patients scheduled for 131I therapy at our hospital between April 2022 and April 2023. Based on MWP, the patients were categorized as standard (no methimazole or MWP > 1 month), MWP1 (MWP ≤ 1 week), MWP2 (MWP > 1 week to ≤2 weeks), and MWP3 (MWP > 2 weeks to <1 month). Fisher's exact test, one-way ANOVA, or Kruskal–Wallis test were used to compare variables. Fitted curves of 99mTcTU20min vs 131IU24h were plotted for the standard group. Linear relationships and Bland–Altman plots were used to illustrate the relationship and consistency between estimated and measured 131IU24h. Results 131IU24h was higher in the MWP1 group compared to MWP2 (70.22 ± 7.95% vs 61.92 ± 9.84%, P = .001), and thyroid mass was greater in the MWP1 group (36.15 ± 22.38 g) vs MWP3 (21.25 ± 11.90 g, P = .005). The relationship between 131IU24h and 99mTcTU20min in the standard group is described by the following algorithm: estimated 131IU24h = 11.3ln (99mTcTU20min) + 39.4 (R2 = 0.62). Based on it, the correlation between estimated and measured 131IU24h was weak in MWP1 and MWP2 (both P > .05) but strong in MWP3 (r = 0.66, P = .002). Additionally, the agreement between estimated and measured 131IU24h was highest in the MWP3 group (95% confidence interval, −15.86 to 15.52%) compared to the MWP1and MWP2 groups. Conclusion Estimated 131IU24h based on 99mTcTU is not suitable for GD patients with MWP less than 2 weeks at our institution, necessitating further prospective multicenter studies for validation.

Purpose To estimate dose–response relationship using dynamic quantitative 99m Tc-pertechnate scintigraphy in head-neck cancer patients treated with parotid-sparing conformal radiotherapy. Methods Dynamic quantitative pertechnate salivary scintigraphy was performed pre-treatment and subsequently periodically after definitive radiotherapy. Reduction in salivary function following radiotherapy was quantified by salivary excretion fraction (SEF) ratios. Dose–response curves were modeled using standardized methodology to calculate tolerance dose 50 (TD50) for parotid glands. Results Salivary gland function was significantly affected by radiotherapy with maximal decrease in SEF ratios at 3-months, with moderate functional recovery over time. There was significant inverse correlation between SEF ratios and mean parotid doses at 3-months (r = −0.589, p < 0.001); 12-months (r = −0.554, p < 0.001); 24-months (r = −0.371, p = 0.002); and 36-months (r = −0.350, p = 0.005) respectively. Using a post-treatment SEF ratio <45% as the scintigraphic criteria to define severe salivary toxicity, the estimated TD50 value with its 95% confidence interval (95% CI) for the parotid gland was 35.1Gy (23.6-42.6Gy), 41.3Gy (34.6-48.8Gy), 55.9Gy (47.4-70.0Gy) and 64.3Gy (55.8-70.0Gy) at 3, 12, 24, and 36-months respectively. Conclusions There is consistent decline in parotid function even after conformal radiotherapy with moderate recovery over time. Dynamic quantitative pertechnate scintigraphy is a simple, reproducible, and minimally invasive test of major salivary gland function.

BACKGROUND: The current standard method in hyperparathyroidism imaging is the combination of [99mTc]Tc-methoxyisobutylisonitrile ([99mTc]Tc-MIBI) single photon emission computed tomography/computed tomography (SPECT/CT) and neck ultrasonography (nUS). However, [99mTc]Tc-MIBI scintigraphy has certain limitations; thus, alternative imaging techniques may be beneficial. The following paper discusses the usefulness of performing an additional 99mTc-pertechnetate ([99mTc]NaTcO₄) SPECT/CT after a standard combination of [99mTc]Tc-MIBI SPECT/CT and neck ultrasonography to improve the efficiency of detecting parathyroid adenomas and/or hyperplasia in inconclusive cases. MATERIAL AND METHODS: The authors retrospectively analyzed archived medical data of 58 patients who underwent parathyroid scintigraphy in 2022–2024. The study consists of patients, in whose cases [99mTc]Tc-MIBI SPECT/CT in combination with nUS did not provide a clear outcome. These patients underwent additional [99mTc]NaTcO4 SPECT/CT imaging. Radiotracer uptake in both studies was then compared visually. RESULTS: Out of 58 patients included in the study, 40 (69%) had positive [99mTc]Tc-MIBI and [99mTc]NaTcO₄ SPECT/CT results, whereas 18 patients (31%) had a negative scintigraphy result. In 42 out of 58 cases, clinical verification of SPECT/CT results was obtained, based on which the sensitivity, specificity, and accuracy of the method were 83.3%. CONCLUSIONS: This study demonstrates that additional [99mTc]NaTcO₄ SPECT/CT can be valuable in patients with inconclusive results in [99mTc]Tc-MIBI SPECT/CT (evaluated in combination with nUS), both to confirm and exclude the presence of hyperfunctioning parathyroid glands.

Quantitative analysis of (99m)Tc-pertechnetate salivary gland scintigraphy has been used in the evaluation of salivary gland function, but so far no one method can be considered optimal for this task. In this study, a semiquantitative method providing 2 functional parameters for objective assessment of salivary gland function by scintillation camera imaging was tested. Twenty-one patients referred for (99m)Tc-pertechnetate thyroid scanning were studied. Two patients with salivary complaints were also included. Dynamic imaging of the anterior head using a scintillation camera was started after a bolus intravenous injection of 185 MBq (5 mCi) (99m)Tc-pertechnetate at 1 frame per 30 s for 30 min. At 15 min after injection, diluted lemon juice was administered orally. Analysis of the dynamic study included time-activity curves of 4 salivary glands (right and left parotid and right and left submandibular). Two parameters of function were defined: uptake rate, taken as the value of the initial slope of the time-activity curve, and washout fraction, which was the relative mobilizable radioactivity from each salivary gland after ingestion of the sialogogue. A parametric image of the washout fraction was also generated. The images showed gradual uptake in the parotid and submandibular glands. Washout was noted immediately after ingestion of the lemon juice. The pattern of the time-activity curve in all glands showed an early fast-rising part followed by a slow-rising component to nearly a plateau within 6-10 min after injection. The mean value of the uptake rate parameter was 0.10 +/- 0.09 cps/s. There was no significant difference between the parotid and submandibular glands or the right and left sides. Uptake in the parotid gland was 1.5-2 times that in the submandibular gland. The washout fraction was 1.40 +/- 1.60 for the parotid glands and 0.77 +/- 0.41 for the submandibular glands (P = 0.005). The quantitative analysis method including the uptake rate and the washout fraction parameters would enable objective assessment of salivary function and provide a reproducible means for follow-up of functional impairment in certain diseases.

Noninvasive bioluminescence imaging (BLI) of luciferase-expressing tumor cells has advanced pre-clinical evaluation of cancer therapies. Yet despite its successes, BLI is limited by poor spatial resolution and signal penetration, making it unusable for deep tissue or large animal imaging and preventing precise anatomical localization or signal quantification. To refine pre-clinical BLI methods and circumvent these limitations, we compared and ultimately combined BLI with tomographic, quantitative imaging of the sodium iodide symporter (NIS). To this end, we generated tumor cell lines expressing luciferase, NIS, or both reporters, and established tumor models in mice. BLI provided sensitive early detection of tumors and relatively easy monitoring of disease progression. However, spatial resolution was poor, and as the tumors grew, deep thoracic tumor signals were massked by overwhelming surface signals from superficial tumors. In contrast, NIS-expressing tumors were readily distinguished and precisely localized at all tissue depths by positron emission tomography (PET) or single photon emission computed tomography (SPECT) imaging. Furthermore, radiotracer uptake for each tumor could be quantitated noninvasively. Ultimately, combining BLI and NIS imaging represented a significant enhancement over traditional BLI, providing more information about tumor size and location. This combined imaging approach should facilitate comprehensive evaluation of tumor responses to given therapies.

The aim of the study was to provide preliminary validation of the utility of co-registered respiratory-gated ventilation/perfusion single-photon emission computed tomography-computed tomography (SPECT-CT) images in the assessment of regional lung functional impairment in patients with lung cancer. Twenty untreated and three radiotherapy-treated patients with lung cancer underwent gated( 99m)Tc-Technegas/macroaggregated albumin (MAA) SPECT, using a triple-headed SPECT unit and a respiratory synchroniser. Gated SPECT images were obtained from 1/8 data centered at peak inspiration for each regular respiratory cycle and co-registered with tidal inspiration CT images using an automated three-dimensional registration tool. Gated SPECT images detected 10.2% more ventilation defects (205 vs 186) and 9% more perfusion defects (218 vs 200) compared with ungated images, with a significantly higher lesion-to-normal lung contrast ( P<0.0001). Co-registered gated SPECT-CT images accurately visualised the anatomy of ventilation and/or perfusion defects associated with bronchial and/or vascular involvement by tumours, resulting in changes in surgical planning in two patients with lung cancer. In the three patients who had received radiotherapy, perfusion defects along the radiation field were identified even in the lung areas without abnormal opacities on CT images. In the operated patients, the co-registered gated SPECT-CT images allowed accurate placement of regions of interest over the lung lobes to be resected, yielding a significantly better prediction of postoperative forced expired volume in 1 s (FEV(1)) compared with that predicted without use of these images ( R=0.993 vs R=0.890; P<0.05), with an excellent inter-observer reproducibility. Detailed functional-morphological correlation on co-registered gated SPECT-CT images contributes to accurate assessment of regional functional impairment, and may be useful for surgical planning, prediction of postoperative function and assessment of external beam radiotherapy effects in patients with lung cancer.