Benign struma ovarii in a patient with invasive papillary thyroid cancer: detection with I-131 SPECT-CT

Radioiodine whole body scan pitfalls in differentiated thyroid cancer

PURPOSE

whole body scan (WBS) performed following diagnostic or therapeutic administration of I-131 is useful in patients with differentiated thyroid carcinoma. However, it can be falsely positive in various circumstances. We aimed to report a series of pitfalls in a clinical perspective.

METHODS

A search in the database PubMed utilizing the following terms: "false radioiodine uptake" and "false positive iodine 131 scan" has been made in January 2023. Among the 346 studies screened, 230 were included in this review, with a total of 370 cases collected. Physiological uptakes were excluded. For each patient, sex, age, dose of I-131 administered, region and specific organ of uptake and cause of false uptake were evaluated.

RESULTS

370 cases of false radioiodine uptake were reported, 19.1% in the head-neck region, 34.2% in the chest, 14.8% in the abdomen, 20.8% in the pelvis, and 11.1% in the soft tissues and skeletal system. The origin of false radioiodine uptake was referred to non-tumoral diseases in 205/370 cases (55.1%), benign tumors in 108/370 cases (29.5%), malignant tumors in 25/370 cases (6.7%), and other causes in 32/370 cases (8.7%).

CONCLUSIONS

WBS is useful in the follow-up of patients with differentiated thyroid carcinoma, however it can be falsely positive in various circumstances. For this reason, it is critically important to correlate the scintigraphic result with patient's medical history, serum thyroglobulin levels, additional imaging studies and cytologic and/or histologic result.

Radioiodine Uptake in Incidentally Detected Neuroendocrine Tumor: Correlative Imaging With FDG PET/CT and 68 Ga-DOTATATE PET/CT

ABSTRACT

Radioiodine whole-body scintigraphy has long been used for detection of differentiated thyroid carcinoma with high avidity in functioning thyroid tissues. However, uptake is not completely specific, and "false-positive" uptake in nonthyroidal tumors have rarely been reported. Herein, we present a case of incidentally detected neuroendocrine tumor showing high radioiodine uptake initially suspected to be thyroid metastasis. Correlative imaging with FDG PET/CT and 68 Ga-DOTATATE PET/CT is presented, and literature survey is discussed. We conclude that neuroendocrine tumor should be added to the reported list of neoplasms that can show "false-positive" uptake representing a potential interpretative pitfall.

Causes of False-Positive Radioactive Iodine Uptake in Patients with Differentiated Thyroid Cancer

Purpose

Radioactive iodine (RAI) whole-body scan is a sensitive imaging modality routinely used in patients with differentiated thyroid cancer to detect persistent and recurrent disease. However, there can be false-positive RAI uptake that can lead to misdiagnosis and misclassification of a patient’s cancer stage. Recognizing the causes of false positivity can avoid unnecessary testing and treatment as well as emotional stress. In this review, we discuss causes and summarize various mechanisms for false-positive uptake.

Recent Findings

We report a patient with differentiated thyroid cancer who was found to have Mycobacterium avium complex infection as the cause of false-positive RAI uptake in the lungs. Using this case example, we discuss and summarize findings from the literature on etiologies of false-positive RAI uptake. We also supplement additional original images illustrating other examples of false RAI uptake.

Summary

False-positive RAI uptake may arise from different causes and RAI scans need to be interpreted in the context of the patient’s history and corresponding cross-sectional imaging findings on workup. Understanding the potential pitfalls of the RAI scan and the mechanisms underlying false uptake are vital in the care of patients with differentiated thyroid cancer.

[18F]Tetrafluoroborate ([18F]TFB) and its analogs for PET imaging of the sodium/iodide symporter

Sodium/iodide symporter (NIS)-mediated iodide uptake in thyroid follicular cells is the basis of clinical utilization of radioiodines. The cloning of the NIS gene enabled applications of NIS as a reporter gene in both preclinical and translational research. Non-invasive NIS imaging with radioactive iodides and iodide analogs has gained much interest in recent years for evaluation of thyroid cancer and NIS reporter expression. Although radioiodines and [^99mTc]pertechnetate ([^99mTc]TcO₄^-) have been utilized in positron emission tomography (PET) and single photon emission computed tomography (SPECT), they may suffer from limitations of availability, undesirable decay properties or imaging sensitivity (SPECT versus PET). Recently, [¹⁸F]tetrafluoroborate ([¹⁸F]TFB or [¹⁸F]BF₄^-) and other fluorine-18 labeled iodide analogs have emerged as a promising iodide analog for PET imaging. These fluorine-18 labeled probes have practical radiosyntheses and biochemical properties that allow them to closely mimic iodide transport by NIS in thyroid, as well as in other NIS-expressing tissues. Unlike radioiodides, they do not undergo organification in thyroid cells, which results in an advantage of relatively lower uptake in normal thyroid tissue. Initial clinical trials of [¹⁸F]TFB have been completed in healthy human subjects and thyroid cancer patients. The excellent imaging properties of [¹⁸F]TFB for evaluation of NIS-expressing tissues indicate its bright future in PET NIS imaging. This review focuses on the recent evolution of [¹⁸F]TFB and other iodide analogs and their potential value in research and clinical practice.

Precise preoperative diagnosis of struma ovarii with pseudo-Meigs' syndrome mimicking ovarian cancer with the combination of 131I scintigraphy and 18F-FDG PET: case report and review of the literature

Background

Struma ovarii is a rare ovarian neoplasm that often appears malignant on conventional imaging. Pseudo-Meigs’ syndrome with ascites, pleural effusion, and elevated serum CA 125 levels is much rarer and leads to misdiagnosis of ovarian cancer and unnecessary extended surgery.

Case presentation

A 50-year-old woman with abdominal distention and dyspnoea was referred to our hospital. Ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) showed a polycystic ovarian tumor with a solid component, pleural effusion, and massive ascites with negative cytology. Her serum CA 125 level was 1237 U/ml, indicating the presence of ovarian cancer. Based on increased uptake of ¹³¹I but no uptake of ¹⁸F–FDG in the tumor, the preoperative diagnosis was struma ovarii with pseudo-Meigs’ syndrome, which was confirmed histologically. She had no evidence of ascites and pleural effusion six months after surgery.

Conclusions

To date, there have been no systematic reviews focused on preoperative diagnosis with imaging modalities. The combination of ¹³¹I scintigraphy and ¹⁸F–FDG PET/CT in addition to conventional imaging modalities can provide the precise preoperative diagnosis of struma ovarii with pseudo-Meigs’ syndrome mimicking ovarian cancer, leading to the appropriate treatment strategy.

Incidental Findings of Intense Radioiodine Uptake in Struma Ovarii and Bilateral Nonlactating Breasts Simultaneously on Postablation 131I SPECT/CT for Papillary Thyroid Cancer

A 52-year-old woman diagnosed with papillary thyroid carcinoma was referred for ¹³¹I therapy following total thyroidectomy. She was given 4,810 MBq (130 mCi) of ¹³¹I following 4 weeks of thyroid hormone withdrawal. A posttherapy scan showed intense, focal activity in the pelvis and intense, diffuse activity on both sides of the chest, which was localized to the right ovary and both breasts on SPECT/CT examination. She had bilateral nipple pain and a history of antidopaminergic drugs as combination medication for her rheumatoid arthritis and prokinetics during radioiodine therapy. On a ¹²³I whole-body scan 9 months later after stopping the drugs, bilateral breast uptake was not visible; however, right ovarian focal uptake was still visualized. Bilateral salpingo-oophorectomy was performed, and revealed struma ovarii with substantial internal necrosis due to radioiodine therapy. This case is interesting as two rare entities, ¹³¹I therapy-related struma ovarii and drug-related breast uptake, were simultaneously visualized.

Endocrine radionuclide scintigraphy with fusion single photon emission computed tomography/computed tomography

AIM: To review the benefits of single photon emission computed tomography (SPECT)/computed tomography (CT) hybrid imaging for diagnosis of various endocrine disorders.

METHODS: We performed MEDLINE and PubMed searches using the terms: “SPECT/CT”; “functional anatomic mapping”; “transmission emission tomography”; “parathyroid adenoma”; “thyroid cancer”; “neuroendocrine tumor”; “adrenal”; “pheochromocytoma”; “paraganglioma”; in order to identify relevant articles published in English during the years 2003 to 2015. Reference lists from the articles were reviewed to identify additional pertinent articles. Retrieved manuscripts (case reports, reviews, meta-analyses and abstracts) concerning the application of SPECT/CT to endocrine imaging were analyzed to provide a descriptive synthesis of the utility of this technology.

RESULTS: The emergence of hybrid SPECT/CT camera technology now allows simultaneous acquisition of combined multi-modality imaging, with seamless fusion of three-dimensional volume datasets. The usefulness of combining functional information to depict the bio-distribution of radiotracers that map cellular processes of the endocrine system and tumors of endocrine origin, with anatomy derived from CT, has improved the diagnostic capability of scintigraphy for a range of disorders of endocrine gland function. The literature describes benefits of SPECT/CT for ^99mTc-sestamibi parathyroid scintigraphy and ^99mTc-pertechnetate thyroid scintigraphy, ¹²³I- or ¹³¹I-radioiodine for staging of differentiated thyroid carcinoma, ¹¹¹In- and ^99mTc- labeled somatostatin receptor analogues for detection of neuroendocrine tumors, ¹³¹I-norcholesterol (NP-59) scans for assessment of adrenal cortical hyperfunction, and ¹²³I- or ¹³¹I-metaiodobenzylguanidine imaging for evaluation of pheochromocytoma and paraganglioma.

CONCLUSION: SPECT/CT exploits the synergism between the functional information from radiopharmaceutical imaging and anatomy from CT, translating to improved diagnostic accuracy and meaningful impact on patient care.

Endocrine scintigraphy with hybrid SPECT/CT

Nuclear medicine imaging of endocrine disorders takes advantage of unique cellular properties of endocrine organs and tissues that can be depicted by targeted radiopharmaceuticals. Detailed functional maps of biodistributions of radiopharmaceutical uptake can be displayed in three-dimensional tomographic formats, using single photon emission computed tomography (CT) that can now be directly combined with simultaneously acquired cross-sectional anatomic maps derived from CT. The integration of function depicted by scintigraphy and anatomy with CT has synergistically improved the efficacy of nuclear medicine imaging across a broad spectrum of clinical applications, which include some of the oldest imaging studies of endocrine dysfunction.

SPECT/CT localization of oral radioiodine activity: a retrospective study and in-vitro assessment

Purpose

We sought to further localize radioiodine activity in the mouth on post-thyroid cancer therapy imaging using single-photon emission computed tomography/computed tomography (SPECT/CT).

Materials and methods

We retrospectively reviewed all patients (58) who underwent thyroid cancer therapy with iodine-131 (¹³¹I) at our institution from August 2009 to March 2011 whose post-therapy radioiodine imaging included neck SPECT/CT. A small group (six) of diagnostic ¹²³I scans including SPECT/CT was also reviewed. Separately, we performed in-vitro ¹³¹I (sodium iodide) binding assays with amalgam and Argenco HP 77 (77% dental gold alloy) as proof of principle for these interactions.

Results

Of the 58 post-therapy patients, 45 (78%) had undergone metallic dental restorations, and of them 41 (91%) demonstrated oral ¹³¹I activity localizing preferentially to those restorations. It was observed that radioiodine also localized to other dental restorations and to orthodontic hardware. Gum-line activity in edentulous patients suggests radioiodine interaction with denture adhesive.

In vitro, dental amalgam and Argenco HP 77 bound ¹³¹I in a time-dependent manner over 1–16 days of exposure. Despite subsequent washings with normal saline, significant ¹³¹I activity (maximally 12% for amalgam and 68% for Argenco HP 77) was retained by these metals. Subsequent soaking in a saturated solution of potassium iodide partially displaced ¹³¹I from amalgam, with near-total displacement of ¹³¹I from Argenco HP 77.

Conclusion

SPECT/CT shows that radioiodine in the oral cavity localizes to metallic dental restorations. Furthermore, in-vitro studies demonstrate partially reversible binding of ¹³¹I to common dental metals.

SPECT/CT evaluation of unusual physiologic radioiodine biodistributions: pearls and pitfalls in image interpretation

Radioiodine imaging has a well-established role in depicting metastatic disease after thyroidectomy in patients with well-differentiated thyroid cancer. Uptake of radioiodine in thyroid metastases depends on expression of sodium-iodide symporter (NIS) by tumor tissues. However, because radioiodine may also accumulate in normal structures and tissues, it is important to distinguish physiologic radioiodine activity from metastatic disease. Furthermore, secretions that contain radioiodine may also simulate pathologic uptake. A spectrum of physiologic distributions, normal variants, and benign mimics of disease have been described in the literature; yet, even when armed with a comprehensive knowledge of these patterns, interpreting radiologists and nuclear physicians may still encounter diagnostic uncertainty. Single-photon emission computed tomography (SPECT) with integrated computed tomography (CT) is a novel technology that, when applied to diagnostic iodine 123 or iodine 131 ((131)I) radioiodine scintigraphy, may accurately localize and help distinguish benign mimics of disease, with the potential to alter the management plan. SPECT/CT is increasingly being used with radioiodine scintigraphy to evaluate patients with thyroid cancer and shows promise for improving imaging specificity and reducing false-positive results.

Radioiodine scintigraphy with SPECT/CT: an important diagnostic tool for thyroid cancer staging and risk stratification

Staging and risk stratification predicate the postoperative management of thyroid cancer patients, determining not only the need for (131)I therapy or alternative options (conservative management without ablation, surgical reintervention, or external-beam radiation therapy) but also the long-term follow-up strategy. This paper presents the progress made in the field of thyroid cancer imaging by application of SPECT/CT technology to radioiodine scintigraphy in both diagnostic and post-therapy settings and reviews the impact of fusion radioiodine imaging on staging, risk stratification, and clinical management of patients with thyroid cancer. In addition, this paper addresses the role of preablation radioiodine imaging and provides nuclear medicine physicians with the background knowledge required for integrating information from fusion imaging into the clinical and histopathologic risk stratification for developing an individualized treatment plan for patients with thyroid cancer.

False-positive I-131 uptake by an ovarian serous cystadenofibroma

We present the case of a 53-year-old woman after thyroidectomy with metastatic multifocal papillary carcinoma and encapsulated focal Hurthle cell carcinoma. Postoperatively, an I-131 whole-body scan revealed uptake in the low midline anterior neck. She was treated with 151.5 mCi of I-131. The 1-year follow-up I-131 whole-body scan revealed a new pelvic mass with I-131 uptake. Pelvic CT showed bilateral complex ovarian masses. She underwent surgical excision, revealing a right ovarian endometriotic cyst and a left ovarian cystadenofibroma, without thyroid tissue involvement. I-131 uptake in a cystadenofibroma is extremely rare and has been reported only once to our knowledge.

I-131 SPECT/CT elucidates cryptic findings on planar whole-body scans and can reduce needless therapy with I-131 in post-thyroidectomy thyroid cancer patients

BACKGROUND

Interpreting I-131 whole-body scans (WBSs) after thyroidectomy for thyroid cancer is not simple. There are scans in which interpretation is speculative because of cryptic findings (CF). Complexity is added in scans that are done a week after an ablative or therapeutic dose of I-131 because not only is I-131-labeled thyroxine (T4) distributed throughout the body, but inorganic I-131 that is derived from the de-iodination of T4 may be also detected. We present our observations regarding the analysis of CF on WBS using I-131 single-photon emission computed tomography (SPECT) in fusion with noncontrast computed tomography (CT), referred to here and elsewhere as I-131 SPECT/CT.

METHODS

Forty of 184 WBSs in 38 thyroidectomized thyroid cancer patients were followed up with I-131 SPECT/CTs. The SPECT/CT images were acquired after a tracer dose of I-131 (n=82) or a week after an ablative or therapeutic dose of I-131 (n=102).

RESULTS

Among 184 WBSs, 40 (22%) had CF. In 35 patients the WBS was negative for metastatic disease except for the CF and 5 patients had evidence of thyroid cancer in addition to the CF. There were 49 CF in the planar scans that were localized by SPECT/CT. These were characterized as physiological uptake in gingiva, thymus, gall bladder, menstrual blood, uterine fibroid, recto-sigmoid, colon, and bladder. Also observed was uptake in sites that represented nonthyroidal pathology including dental abscess, hiatal hernia, renal cyst, and struma ovarii. SPECT/CT suggested that 10 of the CF were actually of thyroid origin. In 40 SPECT/CT scans, the images contributed to interpreting the scan. In 15 of 40 patients the SPECT/CT analysis of WBS was performed with tracer doses of I-131 and was important for determining whether to administer ablative I-131 treatment. In another 25 patients, in whom SPECT/CT was performed after ablative or therapeutic doses of 131-I, information regarding the characterization of CF by SPECT/CT was useful in determining if thyroid cancer metastases or thyroid remnants were present.

CONCLUSIONS

I-131 SPECT/CT is a useful tool to characterize atypical or CF on WBS by differentiating thyroid remnant or cancer from physiologic activity or nonthyroid pathology. In the past, uptake on a WBS that was not explicable as physiologic activity was identified as putative or possible thyroid cancer and generally was treated with I-131. Now, by identifying activity in some possible cancer sites as not thyroid cancer, SPECT/CT can reduce inappropriate treatment with I-131. SPECT/CT of WBS performed after ablative doses of 131-I is useful in determining the nature of CF and therefore likely providing prognostic information.

Incidental finding of ovarian teratoma on post-therapy scan for papillary thyroid cancer and impact of SPECT/CT imaging

A 41-year old woman post thyroidectomy and neck dissection is presented in this case. She initially presented goiter and an enlarged cervical lymph node. She had no family history of cancer or radiation therapy. She had total thyroidectomy and found to have papillary thyroid cancer (T4N1M0). Histopathology report revealed multifocal classical papillary thyroid carcinoma with lympho-vascular invasion, extra-thyroidal extension, and positive lymph nodes. She was treated with 6.5 Gigabecquerel (GBq) of 131Iodine. Whole-body scan showed uptake in the neck and large focus in the left lower abdomen. Single-photon emission computed tomography SPECT/CT demonstrated a round shaped mass in the left pelvis. Pathology revealed cystic teratoma with benign thyroid tissue (struma ovarii), and no malignancy. Two months later, she had the second treatment with 5.5 GBq 131Iodine. Her follow-up stimulated and non-stimulated thyroglobulin levels were significantly lower, and there was no abnormal uptake in the follow-up scan.

Increased serum thyroglobulin levels and negative imaging in thyroid cancer patients: are there sources of benign secretion? A speculative short review

After thyroidectomy and 131I ablation for differentiated thyroid cancer (DTC), serum thyroglobulin (Tg) became a sensitive marker of residual disease. It is not uncommon to find patients at follow-up with persistent serum Tg levels and no other clinical or imaging evidence for the disease. The vast majority of these patients, most probably, have occult foci of disease, often in minute cervical lymph nodes. A review of the literature including papers published on PubMed/Medline until June 2010 was made. In this study we speculated that a minority of patients who had undergone surgery for differentiated thyroid cancer might have benign sources of Tg secretion at follow-up. These sources may be foci of radio-resistant ectopic thyroid tissue or a thyroid stimulating hormone-stimulated thymus.

Incidental scintigraphic detection of struma ovarii following total thyroidectomy for papillary thyroid cancer

A postmenopausal female presented with an enlarging multinodular goiter. Microcalcifications within the largest thyroid nodule found by ultrasound prompted her to elect a total thyroidectomy. Histopathologic evaluation led to the diagnosis of confined papillary thyroid carcinoma (follicular variant). Elevated serum thyroglobulin levels were noted on postoperative laboratory workup, with the differential diagnosis of residual thyroid tissue, substernal extension of an adenomatoid multinodular goiter, and/or metastatic thyroid cancer. The patient then underwent thyrogen-stimulated I-131 ablation therapy, with postablation scans detecting a solitary focus of intensely increased radiotracer accumulation in the midline pelvis. Ultrasound of the pelvis revealed a corresponding right ovarian mass with mixed solid and cystic components. These combined findings were highly suggestive of struma ovarii. An exploratory laparotomy/bilateral salpingo-oophorectomy was performed, and pathologic examination confirmed a mature teratoma with predominant benign thyroid component consistent with struma ovarii.

Hybrid imaging (SPECT/CT and PET/CT)--improving the diagnostic accuracy of functional/metabolic and anatomic imaging

In-line combined systems, single-photon emission computed tomography (SPECT)/computed tomography (CT) and positron emission tomography (PET)/CT, allow an instant generation of fused images of scintigraphy and CT data. The accumulated clinical data on the use of these systems in various clinical scenarios indicate that this hybrid technology improves the diagnostic accuracy as compared to scintigraphy and CT alone and even to side-by-side interpretation of scintigraphy and CT, which were acquired separately. The improved diagnostic accuracy is reflected by improving image quality of SPECT and PET, detection of more clinically relevant lesions, better localization of disease and differentiation between physiologic and pathologic uptake, characterization of disease by its functional and morphologic appearance before and after therapy and accurate delineation of disease, optimizing biopsy and therapy planning.

Clinical relevance of single-photon emission computed tomography/computed tomography of the neck and thorax in postablation (131)I scintigraphy for thyroid cancer

CONTEXT

In patients with differentiated thyroid carcinoma, postablation (131)I scintigraphy aims to detect residual neck disease and distant metastases, usually found in lungs and bones. New hybrid single-photon emission computed tomography/computed tomography (SPECT-CT) cameras that permit functional and anatomical image fusion may improve its clinical relevance.

OBJECTIVE

Our objective was to test the added value of neck and thorax SPECT-spiral CT to whole-body scan (WBS) in postablation (131)I scintigraphy.

DESIGN AND SETTING

This was a single-referral-center prospective study with a median follow-up of 21 months.

PATIENTS AND METHODS

Postablation (131)I WBS and neck and thorax SPECT-CT were performed in 55 consecutive patients treated in 2006. WBS and SPECT-CT data were blindly reviewed, scored negative (benign), positive (malignant), or indeterminate and were correlated to the patient outcome.

RESULTS

At patient level, WBS and SPECT-CT were negative in 67 and 78% of patients, positive in 4 and 15%, and indeterminate in 29 and 7%, respectively. Overall, nine patients (16%) presented treatment failure (persistent or recurrent disease) 1-16 months after radioiodine ablation. In the 16 patients with indeterminate WBS, negative SPECT-CT ruled out suspicion of disease in nine of nine patients, and positive SPECT-CT confirmed malignant lesions in four of five patients. Positive SPECT-CT predicted treatment failure better than positive WBS (McNemar's test, P = 0.03).

CONCLUSIONS

This study demonstrates the complementary role of neck and thorax SPECT-CT to WBS in postablation (131)I scintigraphy. Because SPECT-CT allows one to confirm or to rule out residual disease in most cases where WBS remains indeterminate, we recommend its use when available.

Incremental value of 131I SPECT/CT in the management of patients with differentiated thyroid carcinoma

(131)I whole-body scintigraphy (WBS) is a highly sensitive method for the detection of differentiated thyroid tumors and metastases. However, a lack of anatomic landmarks and the physiologic accumulation of the tracer complicate interpretation of the images. This prospective study was designed to evaluate the incremental value of (131)I SPECT/CT over planar WBS in the management of patients with differentiated thyroid carcinoma (DTC).

METHODS

Planar imaging was performed on 66 consecutive DTC patients who were considered to have locally advanced or metastatic disease after total or nearly total thyroidectomy. SPECT/CT was added for patients whose planar findings were inconclusive. The planar images were interpreted by 2 experienced nuclear medicine physicians. Interpretation of the SPECT/CT images was a consensus opinion of one of the nuclear medicine physicians and an experienced radiologist. Fusion images were considered to improve image interpretation when they better localized sites of increased (131)I uptake. The final diagnosis was verified by pathologic findings, other imaging modalities, and clinical follow-up. Both site-based and patient-based analyses were performed, and the impact of SPECT/CT results on therapeutic strategy was assessed.

RESULTS

A total of 232 foci were observed by (131)I WBS, including 33.2% of foci localized in the thyroid bed, 62.1% due to malignant lesions, and 4.7% caused by nonthyroidal physiologic or benign uptake or a contaminant. Overall, 37 SPECT/CT studies were performed on 23 patients, whose planar images showed 81 inconclusive lesions. Precise localization and characterization of (131)I-avid foci were achieved through (131)I SPECT/CT in 69 (85.2%) and 67 (82.7%) of the 81 foci, respectively. Fusion images were considered to be of benefit in 17 (73.9%) of 23 patients. The therapeutic strategy was changed in 8 (47.1%) of 17 patients. Uncommon metastatic lesions were found in 9 (13.6%) of 66 patients with regard to SPECT/CT fusion images.

CONCLUSION

Fusion of SPECT and CT images was of incremental value over WBS in increasing diagnostic accuracy, reducing pitfalls, and modifying therapeutic strategies in 73.9% of DTC patients. As SPECT/CT techniques emerge, (131)I SPECT/CT may demonstrate higher value than WBS in the management of DTC.

SPECT/CT imaging: clinical utility of an emerging technology

Single-photon emission computed tomography (SPECT) has been a mainstay of nuclear medicine practice for several decades. More recently, combining the functional imaging available with SPECT and the anatomic imaging of computed tomography (CT) has gained more acceptance and proved useful in many clinical situations. Most vendors now offer integrated SPECT/CT systems that can perform both functions on one gantry and provide fused functional and anatomic data in a single imaging session. In addition to allowing anatomic localization of nuclear imaging findings, SPECT/CT also enables accurate and rapid attenuation correction of SPECT studies. These attributes have proved useful in many cardiac, general nuclear medicine, oncologic, and neurologic applications in which the SPECT results alone were inconclusive. Optimal clinical use of this rapidly emerging imaging modality requires an understanding of the fundamental principles of SPECT/CT, including quality control issues as well as potential pitfalls and limitations. The long-term clinical and economic effects of this technology have yet to be established.