Can I-124 PET/CT Predict Pathological Uptake of Therapeutic Dosages of Radioiodine (I-131) in Differentiated Thyroid Carcinoma?

Lammers, Gauke K.; Esser, Jan Paul; Pasker, Pieternel; Praag, Marina E. Sanson-van; Klerk, John M. H. de

doi:10.4236/ami.2014.43004

Cited by 10 publications

(12 citation statements)

References 16 publications

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“…The findings of the present study are in contrast to those of recently published studies (17,18). Lammers et al analyzed 30 patients, and their Table 1 indicates that only 7 of them underwent subsequent radioiodine treatment (17).…”

Section: Discussioncontrasting

confidence: 99%

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High Level of Agreement Between Pretherapeutic ¹²⁴I PET and Intratherapeutic ¹³¹I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

et al. 2016

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The aim of this retrospective study was to assess the level of agreement between PET and scintigraphy using diagnostic amounts of 124 I and therapeutic amounts of 131 I, respectively, in detecting iodinepositive metastases in patients with differentiated thyroid carcinoma. Methods: The study included patients who underwent PET/CT 24 and 120 h after administration of approximately 25 MBq of 124 I and subsequently underwent imaging 5-10 d after administration of 1-10 GBq of 131 I. For each patient, the intratherapeutic 131 I imaging comprised a whole-body scintigraphy scan and a SPECT/CT scan of the neck to distinguish between metastatic and thyroid remnant tissues. Iodine uptake was rated as a metastatic focus if located outside the thyroid bed. Lesion-and patient-based analyses were performed. Results: The study included 137 patients with 227 metastases iodine-positive on both functional imaging modalities. In the lesion-based analysis, 124 I PET and 131 I imaging detected 98% (223/227) and 99% (225/227) of the iodine-positive metastases, respectively; the level of agreement between 124 I PET and 131 I imaging was 97% (221/227). Four metastases (3 lymph node and 1 bone) in 4 patients were 124 I-negative but 131 Ipositive, and 2 lymph node metastases in 2 patients were 131 I-negative but 124 I-positive. In the patient-based analysis, 61 of the 137 patients presented with iodine-positive metastases. 124 I PET and 131 I imaging detected at least one iodine-positive metastasis in 97% (59/61) and 98% (60/61) of the patients, respectively. The level of agreement was 95% (58/61). Both imaging modalities concordantly identified 76 of 137 patients without pathologic iodine uptake. Conclusion: Because of the high level of agreement, pretherapeutic 124 I PET/CT is an adequate methodology in the detection of iodine-positive metastases and can be used as a reliable tool for staging of thyroid cancer patients and individualized treatment planning.

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Section: Discussioncontrasting

confidence: 99%

“…Several studies have also shown the superiority of 124 I PET over intratherapeutic 131 I imaging after application of a therapeutic amount of 131 I activity (1,7,9). However, other studies (17,18) have found that 124 I PET may be inferior.…”

Section: Discussionmentioning

confidence: 92%

High Level of Agreement Between Pretherapeutic ¹²⁴I PET and Intratherapeutic ¹³¹I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

et al. 2016

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“…Several clinical studies have been performed with 124 I activities lower than 74 MBq (8,9,11). The probability of a false-negative 124 I PET/CT result as compared with posttherapeutic 131 I SPECT/CT considerably increases with lower 124 I activities.…”

Section: Discussionmentioning

confidence: 99%

“…124 I is a positron emitter and can be imaged using PET, with resolution, sensitivity, and quantitation superior to those obtainable with the use of 131 I in scintigraphy or SPECT. Relatively low activities of 20-74 MBq are used for diagnostic 124 I PET imaging (8)(9)(10)(11)(12)(13).…”

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confidence: 99%

“…Unfortunately, clinical experience has shown that 124 I PET/CT does not always predict uptake of 131 I reliably, and discrepancies between posttherapeutic 131 I SPECT/CT and pretherapeutic 124 I PET/CT have been reported by several groups (8)(9)(10)(11)(12)(13). More specifically, in some cases 124 I PET/CT images showed no uptake whereas 131 I SPECT/CT images did.…”

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Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

et al. 2015

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Radioiodine therapy with 131 I is used for treatment of suspected recurrence of differentiated thyroid carcinoma. Pretherapeutic 124 I PET/CT with a low activity (∼1% of 131 I activity) can be performed to determine whether uptake of 131 I, and thereby the desired therapeutic effect, may be expected. However, false-negative 124 I PET/CT results as compared with posttherapeutic 131 I SPECT/CT have been reported by several groups. The purpose of this study was to investigate whether the reported discrepancies may be ascribed to a difference in lesion detectability between 124 I PET/CT and 131 I SPECT/CT and, hence, whether the administered 124 I activity is sufficient to achieve equal detectability. Methods: Phantom measurements were performed using the National Electrical Manufacturers Association 2007 image-quality phantom. As a measure of detectability, the contrast-to-noise ratio was calculated. The 124 I activity was expressed as the percentage of 131 I activity required to achieve the same contrast-to-noise ratio. This metric was defined as the detectability equivalence percentage (DEP). Results: Because lower DEPs were obtained for smaller spheres, a relatively low 124 I activity was sufficient to achieve similar lesion detectability between 124 I PET/CT and 131 I SPECT/CT. DEP was 1.5%, 1.9%, 1.9%, 4.4%, 9.0%, and 16.2% for spheres with diameters of 10, 13, 17, 18, 25, and 37 mm, respectively, for attenuation-and scatter-corrected SPECT versus point-spread function (PSF) model-based and time-of-flight (TOF) PET. For no-PSF no-TOF PET, DEP was 3.6%, 2.1%, 3.5%, 7.8%, 15.1%, and 23.3%, respectively. Conclusion: A relatively low 124 I activity of 74 MBq (∼1% of 131 I activity) is sufficient to achieve similar lesion detectability between 124 I PSF TOF PET/CT and 131 I SPECT/CT for small spheres (#10 mm), since the reported DEPs are close to 1%. False-negative 124 I PET/CT results as compared with posttherapeutic 131 I SPECT/CT may be ascribed to differences in detectability for large lesions (.10 mm) and for no-PSF no-TOF PET, since DEPs are greater than 1%. On the basis of DEPs of 3.5% for lesion diameters of up to 17 mm on no-PSF no-TOF PET, 124 I activities as high as 170 MBq may be warranted to obtain equal detectability.

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A phantom study: Should ¹²⁴I‐mIBG PET/CT replace ¹²³I‐mIBG SPECT/CT?

et al. 2017

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Purpose: The isotope 123 I is commonly labeled with meta-iodobenzylguanidine (mIBG) for imaging of neuroendocrine tumors, such as pheochromocytomas and neuroblastomas. 123 I-mIBG SPECT/CT imaging is performed for staging, follow-up and selection of patients for treatment with 131 I mIBG. As an alternative to 123 I, 124 I-mIBG PET/CT may be used, potentially taking advantage of the superior PET image quality. The purpose of this study was to investigate whether 124 I PET/ CT improves image quality as compared with 123 I SPECT/CT for equal patient effective radiation dose (in mSv). Methods: Phantom measurements were performed using the NEMA-2007 image quality phantom. SPECT and PET reconstruction settings were used with and without time-of-flight (TOF) and pointspread-function (PSF) modeling. As a measure of image quality, the contrast-to-noise ratio (CNR) was calculated. The ratio of the 123 I to 124 I activity concentration was determined at which the contrast-to-noise ratio was equal for both modalities. This metric was defined as the contrast equivalent activity ratio (CEAR). Results: CEARs of 47.7, 25.6, 23.1, 14.6, 10.0, and 9.1 were obtained for a TOF and PSF modeled 124 I reconstruction method and an attenuation and scatter-corrected 123 I reconstruction method for sphere sizes of 10 to 37 mm, respectively. As the effective radiation dose of 124 I-mIBG is higher than of 123 I-mIBG (in mSv/MBq), an equal effective dose corresponds to a CEAR of 5 to 10. Therefore, CEARs higher than 5 to 10 indicate that 124 I PET/CT outperforms 123 I SPECT/CT in the sense of image quality for equal patient effective radiation dose. Conclusion: The CEAR is much larger than a factor of 5 to 10 (needed for equal patient effective radiation dose) for most of the reconstruction methods and sphere sizes. Therefore, 124 I-mIBG PET/ CT is expected to improve image quality and/or may be used to reduce effective patient dose as compared with 123 I-mIBG SPECT/CT.

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Can I-124 PET/CT Predict Pathological Uptake of Therapeutic Dosages of Radioiodine (I-131) in Differentiated Thyroid Carcinoma?

Cited by 10 publications

References 16 publications

High Level of Agreement Between Pretherapeutic ¹²⁴I PET and Intratherapeutic ¹³¹I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

High Level of Agreement Between Pretherapeutic ¹²⁴I PET and Intratherapeutic ¹³¹I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

A phantom study: Should ¹²⁴I‐mIBG PET/CT replace ¹²³I‐mIBG SPECT/CT?

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Can I-124 PET/CT Predict Pathological Uptake of Therapeutic Dosages of Radioiodine (I-131) in Differentiated Thyroid Carcinoma?

Cited by 10 publications

References 16 publications

High Level of Agreement Between Pretherapeutic 124I PET and Intratherapeutic 131I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

High Level of Agreement Between Pretherapeutic 124I PET and Intratherapeutic 131I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

Quantitative Comparison of 124I PET/CT and 131I SPECT/CT Detectability

A phantom study: Should 124I‐mIBG PET/CT replace 123I‐mIBG SPECT/CT?

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High Level of Agreement Between Pretherapeutic ¹²⁴I PET and Intratherapeutic ¹³¹I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

High Level of Agreement Between Pretherapeutic ¹²⁴I PET and Intratherapeutic ¹³¹I Imaging in Detecting Iodine-Positive Thyroid Cancer Metastases

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

A phantom study: Should ¹²⁴I‐mIBG PET/CT replace ¹²³I‐mIBG SPECT/CT?