Initial staging of differentiated thyroid carcinoma: continued utility of posttherapy 131I whole-body scintigraphy.

PURPOSE: To retrospectively compare pretherapy iodine 123 ((123)I) and posttherapy iodine 131 ((131)I) sodium iodide whole-body scintigraphy of patients with newly diagnosed differentiated thyroid cancer to determine if there is significant and clinically relevant discordance of nonphysiologic iodide-avid foci (IAFs) between the two examinations. MATERIALS AND METHODS: This study was approved by the Institutional Review Board, the requirement for informed consent was waived, and the study complied with HIPAA. The authors identified 108 patients (88 women, 20 men; age range, 16-86 years; mean, 47.5 years; 45 patients younger than 45 years, 63 patients 45 years and older) who previously had undergone total or near-total thyroidectomy for differentiated thyroid carcinoma. Each patient had undergone a pretherapy ( 123)I whole-body scan followed by a posttherapy ( 131)I whole-body scan. The number and location of IAFs were recorded on both scans. Data were compared by using a Wilcoxon signed rank test for paired data and assessed clinical relevance based on changes in tumor staging. RESULTS: Posttherapy ( 131)I whole-body scans revealed additional IAFs outside the thyroid bed not detected on pretherapy ( 123)I scans in 21 (19%, P < .001) of 108 patients. Nineteen (90%) of these 21 had IAFs in new locations (P < .001), with tumor upstaging of 11 (59%, 10% of total) of those 19 patients; six (55%, 6% of total) of those 11 had scintigraphic patterns consistent with unsuspected metastatic disease. Concordant scintigraphic patterns were observed in 87 (81%) of 108. CONCLUSION: In patients with newly diagnosed differentiated thyroid cancer who had undergone thyroidectomy and ( 131)I ablation, posttherapy ( 131)I whole-body scintigraphy revealed new IAFs in 18% and clinical upstaging occurred in 10% of patients compared with pretherapy ( 123)I whole-body scintigraphy. Therefore, posttherapy ( 131)I whole-body scintigraphy provides incremental clinically relevant information as it helps to establish the true extent of IAFs and may contribute to altering of staging.

Optimal scintigraphic evaluation of a hydronephrotic horseshoe kidney.

A 25-y-old man with horseshoe kidney was referred for diuretic-augmented renal scintigraphy. Single-detector dynamic posterior imaging was performed and revealed asymmetric retention of radiotracer in the left collecting system. Renal scintigraphy was repeated with a modified protocol. Dynamic imaging was performed this time using dual-detector acquisition of both anterior and posterior data. Thereafter, pregravity and subsequently postgravity static images were obtained in both anterior and posterior projections. This second study showed near-complete emptying of the left collecting system. This case illustrates the utility of using simultaneous anterior and posterior imaging and geometric mean calculations for functional analysis and also highlights the value of physiologic maneuvers to augment the traditional diuretic challenge.

Endocrine neoplasm scintigraphy: added value of fusing SPECT/CT images compared with traditional side-by-side analysis.

PURPOSE: Positron emission tomography (PET)/computed tomography (CT) imaging integrates physiology and anatomy, providing a powerful dual-modality approach. Analogously, fusing independently acquired single photon emission computed tomography (SPECT) and CT images can overcome interpretive challenges in characterizing and localizing abnormalities by either modality alone, potentially enhancing diagnostic confidence. This study explores the added value of SPECT/CT image fusion compared with traditional "side-by-side" SPECT/CT image review for a variety of endocrine neoplasms. METHODS AND MATERIALS: We identified 11 abnormal endocrine neoplasm SPECT scans in 10 patients with contemporary relevant CT scans. These cases included: 4 I-131 (posttherapy thyroid cancer), 2 I-123 (pretherapy thyroid cancer), 2 In-111 OctreoScan (neuroendocrine neoplasm), one Tc-99m sestamibi (thyroid cancer), one Tc-99m tetrofosmin (parathyroid adenoma), and one I-123 MIBG (adrenergic neoplasm). SPECT and CT images were uploaded onto side-by-side workstations, one with fusion software. Two experienced nuclear radiologists first reviewed "side-by-side" SPECT/CT images followed by fused SPECT/CT images. They scored 2 parameters-anatomic localization and diagnostic confidence-using a 4-point scale (1 "not helpful" to 4 "very helpful"). Score differences > or =1 indicated "added value"; < or =0 indicated "lack of added value." RESULTS: Compared with "side-by-side" SPECT/CT images, fused SPECT/CT images yielded "added value" for anatomic localization and diagnostic confidence in two thirds of cases. Fusion led to altered diagnoses in 4 of 11 examinations. Greater confidence was also achieved in 3 of 4 when the interpretation was changed and in 4 of 7 cases when it was not. CONCLUSIONS: CT correlation can be helpful in interpreting endocrine neoplasm SPECT imaging. SPECT/CT image fusion outperformed "side-by-side" SPECT/CT analysis for neoplasm anatomic localization and diagnostic confidence. Therefore, SPECT/CT fusion should be performed routinely because it potentially influences clinical decision-making and patient management.

Infection scintigraphy: added value of single-photon emission computed tomography/computed tomography fusion compared with traditional analysis.

PURPOSE: Positron emission tomography (PET)/computed tomography (CT) imaging is a powerful dual-modality integrating physiology and anatomy. Analogously, fusing separate single-photon emission computed tomography (SPECT) and CT images can overcome interpretive challenges in characterizing and localizing abnormalities. This study explores the value of SPECT/CT image fusion compared with traditional "side-by-side" SPECT-CT image review for infectious /inflammatory processes. METHODS AND MATERIALS: We identified 17 abnormal infection/inflammation SPECT scans in 16 patients (11 indium 111 WBC and 6 gallium citrate Ga 67) with a contemporary CT scan. The SPECT and CT images were uploaded onto "side-by-side" workstations, one with fusion software. Two nuclear radiologists reviewed "side-by-side" SPECT and CT images and fused SPECT/CT images. They scored 2 parameters (anatomical localization and diagnostic confidence) using a 4-point scale (1 "not helpful" to 4 "very helpful"). Score differences more than 1 indicated "added value" and less than 0, "no added value". RESULTS: Compared with "side-by-side" SPECT-CT, fused SPECT/CT images yielded "added value" for anatomical localization in 65%, diagnostic confidence in 71%, and altered interpretations in 47% of cases. Greater confidence was achieved in 75% of cases with altered interpretations and 55% of unaltered cases. CONCLUSIONS: The SPECT/CT image fusion outperformed "side-by-side" SPECT/CT review for anatomical localization and diagnostic confidence of infectious/inflammatory abnormalities. Therefore, SPECT/CT fusion potentially influences clinical decisions and treatment options.

Use of the navigator probe after radiotracer injection to identify nonpalpable rib lesions requiring surgical resection.

BACKGROUND: : Patients with nonpalpable rib lesions (NPRL) requiring biopsy present a challenging problem for the thoracic surgeon. Ideally, a small incision directly over the NPRL should be performed to minimize morbidity, particularly if the lesion is benign. The Navigator probe is routinely used after lymphoscintigraphy by surgical oncologists to isolate sentinel lymph nodes requiring removal, but can also be used to guide resection of nonpalpable focal rib lesions demonstrating increased technetium-99m hydroxymethylene diphosphonate (Tc-99m HDP) uptake. This report describes our initial experience with this technique. METHODS: : Over a 5-month period, 3 patients with focal NPRL underwent rib resection. All patients had solitary lesions demonstrated on recently performed Tc-99m HDP bone scanning. Prior cancers were reported in 2 patients, and pain in 2 patients. Before surgery, all patients underwent intravenous injection of 20 to 25 mCi Tc-99m HDP at least 2 hours before the Navigator probe-guided procedure. RESULTS: : The Navigator probe identified all 3 lesions, allowing a single 4 cm or smaller incision in all cases. Histology included metastatic breast cancer (1), pathologic fracture secondary to metastatic palatal cancer (1), and eosinophilic granuloma (1). No patient required further resection. CONCLUSIONS: : Intraoperative localization of NPRL that are positive on Tc-99m HDP bone scanning using the Navigator probe is feasible and was 100% successful in our initial experience. This technique allows a minimally invasive approach, which is beneficial for those patients who do not require further resection.