Incidence of radioiodine induced Graves' disease in patients with multinodular toxic goiter.

In this study, we assessed the incidence of Graves' disease (GD) following radioiodine therapy (RIT) in a large cohort of well characterized patients with autonomy in comparison to the clinical course of control patients with thyroidal autonomy not definitively treated with (131)I or surgery. 622 consecutive patients were treated with (131)I for autonomy (unifocal: n = 321; multifocal: n = 199; disseminated: n = 102) and followed up for at least 6 months post RIT. 108 consecutive patients with autonomy not definitively treated (unifocal: n = 49; multifocal: n = 42; disseminated: n = 11) followed up for at least 6 months served as controls. Initial evaluation and follow-up included determination of FT3, FT4, TSH, autoantibodies against the thyroid peroxidase (anti-TPO) and TSH-receptor antibodies (TRAb) by highly sensitive radio receptor-assay, quantitative thyroid scintigraphy and sonography. After 6 months, GD was newly diagnosed in 1/321 patients with unifocal autonomy, in 1/199 patients with multifocal autonomy and in 0/108 control patients. In patients with disseminated autonomy (group C), GD was diagnosed significantly more often compared to the other groups (5/102 patients; 4,1 %; p < 0.05). In conclusion, RIT may induce Graves' disease in a few cases with toxic multinodular goiter. The incidence in this population is small. Compared with patients suffering from uni- or multifocal autonomy, subjects with disseminated autonomy have a more than tenfold higher risk for the development of GD.

[Improvement of tomographic reconstruction in bone SPECT]. / Optimierung der tomographischen Rekonstruktion in der Skelett-SPECT.

AIM: The comparison between iterative reconstruction and filtered backprojection in the reconstruction of bone SPECT in the diagnosis of skeletal metastases. PATIENTS, METHODS: 47 consecutive patients (vertebral segments: n = 435), with suspected malignancy of the vertebral column, were examined by bone scintigraphy and MRI (maximal interval between the two procedures +/- 5 weeks). The SPECT-data were reconstructed with an iterative algorithm (ISA) and with filtered backprojection. We defined semiquantitative criteria in order to assess the quality of the tomograms. Conventional reconstruction was performed both by a Wiener-filter and a low-pass-filter. Iterative reconstruction was performed by the ISA algorithm. The clinical evaluation of the different reconstruction algorithms was performed by MRI as the gold-standard. RESULTS: Sensitivity (%): 87.3 (ISA), 86.4 (low-pass), 79.7 (Wiener); specificity (%): 95.3 (ISA), 95 (low-pass), 85.4 (Wiener). The sensitivity of iterative reconstructed SPECT and low-pass reconstructed SPECT was significantly higher (p < 0.05) compared with the sensitivity of SPECT reconstructed by the Wiener-filter. The specificity of iterative reconstruction ISA and low-pass-filter reconstructed SPECT were significantly higher compared with the SPECT data reconstructed by the Wiener-filter. ISA was significantly superior to the Wiener-SPECT relating to all criteria of quality. Iterative reconstruction was significantly superior to the low-pass-SPECT relating to 2 of 3 criteria. In addition the Wiener-SPECT was significantly inferior to the low-pass-SPECT regarding to 2 of 3 criteria. CONCLUSION: In our series the iterative algorithm ISA was the method of choice in the reconstruction of bone SPECT data. In comparison with conventional algorithms ISA offers a significantly higher quality of the tomograms and yields a high diagnostic accuracy.

Expression of the sodium iodide symporter in differentiated thyroid cancer: clinical evidence.

AIM: Molecular analysis of the expression of the sodium iodide symporter (NIS) in 32 patients with differentiated thyroid cancer (DTC) and correlation with scintigraphic findings ((131)I,(123)I) in 19 (59.4%) of them. PATIENTS, METHODS: NIS expression of 27 primary tumours, 13 lymphnodes and 18 distant metastases was determined by immunostaining using a murine monoclonal anti-NIS-antibody. NIS expression and radionuclide uptake of metastases were analysed by a semiquantitative visual score. Patients were divided into two subgroups: Group 1 (n = 8 patients): indirect correlation of radioiodine uptake (RIU) of subsequent metastases with NIS expression of 7 primary tumours and 3 metastases; Group 2 (n=11 patients): direct correlation of radionuclide uptake with NIS expression of 19 metastases which were excised after imaging. RESULTS: 49 of 58 specimens (84.5%) were NIS-positive. A preserved NIS-expression was found in 12 primary tumours and 8 of 10 (80%) synchrone and 6 of 7 (85.7%) metachrone metastases. Group 1 revealed a 100% positive predictive value (PPV) of a preserved NIS expression in the primary tumour regarding radioiodine uptake in metastases while a lack of NIS expression in the primary tumor did not reliable predict a loss of the metastases' ability to concentrate radioiodine. In group 2, only 11 of 19 (57.9%) specimens showed a concordant NIS expression and RIU whereas in the remaining 8 cases without visible RIU NIS expression was still present. CONCLUSIONS: NIS expression of the primary tumour and metastases in DTC is usually well preserved. We found a positive correlation between NIS expression of the primary and metastatic tissue but could not identify such well correspondence between NIS expression and the RIU of subsequent metastases.

Diagnosis and follow up of aortitis in the elderly.

OBJECTIVES: To evaluate the correlation of MRI and [(18)F]FDG-PET scans with the clinical course and inflammatory markers in patients with aortitis. METHODS: Eight patients with aortitis presenting with unspecific GCA-like symptoms were examined. Aortitis was diagnosed and followed up by [(18)F]FDG-PET and MRI. The aorta was divided into three vascular regions (ascending aorta, aortic arch, and descending aorta) to localise the aortic inflammation and compare both imaging techniques. RESULTS: were correlated with clinical and laboratory examinations. RESULTS: At diagnosis, 20/24 vascular regions from eight patients were positive by [(18)F]FDG-PET scan and 15/21 aortic regions by MRI. Patients were treated with corticosteroids and followed up for a mean (SD) of 13.3 (4.7) months. In [(18)F]FDG-PET, 11/20 (55%) initially pathological aortic regions returned to normal in the follow up examination, which correlated closely with the clinical and laboratory follow up examination. Conversely, in MRI, 14/15 initially affected vascular regions were unchanged. CONCLUSIONS: [(18)F]FDG-PET and MRI are both effective techniques for detecting early aortitis and have a high correlation with laboratory inflammatory measures. However, during the follow up examination, [(18)F]FDG-PET uptake decreased in line with the clinical symptoms and inflammatory serum markers, whereas MRI scans gave more static results.

Quantitative thyroid scintigraphy for the differentiation of Graves' disease and hyperthyroid autoimmune thyroiditis.

AIM: The TCTUs (global (99m)Tc-pertechnetate thyroid uptake under suppression) can be used as an estimate of the iodine clearance of non-TSH regulated tissue. High TCTUs levels are characteristic for Graves' disease (GD). Decreased uptake has been described in autoimmune thyroiditis (AIT). However, systematically investigated data in a larger series of AIT-patients with subclinical or overt hyperthyroidism are not published so far. The purpose of this study is the evaluation of the TCTUs in the differentiation between AIT and GD in patients with hyperthyroidism. METHODS: We determined the TCTUs in 59 patients with untreated hyperthyroid GD and in 51 patients with AIT who had subclinical or manifest hyperthyroidism without medication. Patients with GD were characterized by the presence of hyperthyroidism, decreased echogenicity of the thyroid, elevation of TSH-receptor autoantibodies (TRAb). AIT was defined by a decreased echogenicity of the thyroid, absence of elevated TSH-receptor autoantibodies (TRAb), autoantibodies against the thyroid peroxidase (anti-TPO) and spontaneous remission or development of subclinical hypothyroidism within 3 months. RESULTS: Thyroid volumes of patients with AIT were significantly lower than those of patients with GD (p <0.05). TRAb levels were significantly higher in GD-patients (median: 19.5 U/ml; range: 15.3-35 U/ml) than in AIT-patients (median: 1.3 U/ml; range: 0-4.1 U/ml). 73% (38/59) of patients with GD had elevated anti-TPO levels. In these patients anti-TPO levels (median: 768 U/l; range: 83-6397 U/l) were not significantly different from anti-TPO levels of patients with AIT (median: 834 U/l; range: 107-8675 U/l; p = 0.17). TCTUs values of patients with AIT were significantly lower (p <0.05; median: 0.9%; range: 0.1-3.2%) than those of patients with GD (median: 5.7%; range: 1.9-28.3%). CONCLUSION: In our patients quantitative thyroid scintigraphy with (99m)TcO(4)(-) offered rapid and reliable differentiation between hyperthyroid GD and AIT.

[Clinical evaluation of a new thyroglobulin immunoradiometric assay in the follow-up of differentiated thyroid carcinoma]. / Klinischer Stellenwert eines neuen Thyreoglobulin-immunoradiometrischen Assays in der Nachsorge des differenzierten Schilddrüsenkarzinoms.

AIM: Formal and clinical comparison of a new 3 (rd) -generation-Tg-IRMA (3-G-IRMA; Dynotest Tg-plus) with a conventional Tg-IRMA (3-G-IRMA; SELco Tg-assay) for patients with differentiated thyroid carcinoma. In addition we evaluated, if thyroglobulin (Tg) levels above a specific threshold concentration indicate the need for further investigations for residual disease. PATIENTS, METHODS: Tg concentration of 105 sera of 93 consecutive patients with a differentiated thyroid cancer was determined with both assays and compared at different cut-off values (Dynotest Tg-plus: 0.2, 1, 2 ng/ml; SELco Tg-assay: 0.5, 1, 2 ng/ml) with the clinical results in respect to the corresponding TSH concentration. RESULTS: Tg concentration did not show any significant difference (SELco Tg-assay 0.5 ng/ml, Dynotest Tg-plus 0.2 ng/ml). The Tg-values of both assays correlated with 97%. However, correlation of recovery in both assays was small (40%). The sensitivities and specificities of both assays at different cut-offs and TSH values did not reveal significant differences. In patients with TSH concentration > 30 micro U/ml the functional assay sensitivity was superior to arbitrary cut-offs in the decision to start further evaluations. CONCLUSIONS: In our study neither formal nor clinical significant differences between two Tg-assays were found. In a hypothyroid patient (TSH > 30 micro U/ml, Tg concentration exceeding the functional assay sensitivity) further investigations for residual disease are warranted. Higher thresholds are of limited value, due to an unacceptably high rate of false negative results.

Early diagnosis and follow-up of aortitis with [(18)F]FDG PET and MRI.

The aim of this prospective study was to compare fluorine-18 fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) with magnetic resonance imaging (MRI) in patients with early aortitis, at the time of initial diagnosis and during immunosuppressive therapy. The study population consisted of 15 patients (nine females and six males; median age 62 years, range 26-76 years) who presented with fever of unknown origin or an elevated erythrocyte sedimentation rate or elevated C-reactive protein and who showed pathological aortic [(18)F]FDG uptake. Fourteen of these patients had features of early giant cell arteritis (GCA), while one had features of early Takayasu arteritis. During follow-up, seven PET scans were performed in six patients with GCA 4-30 months (median 19 months) after starting immunosuppressive medication. The results of [(18)F]FDG imaging were compared with the results of MRI at initial evaluation and during follow-up and with the clinical findings. At baseline, abnormal [(18)F]FDG uptake was present in 59/104 (56%) of the vascular regions studied in 15 patients. Seven follow-up PET studies were performed in six patients. Of 30 regions with initial pathological uptake in these patients, 24 (80%) showed normalisation of uptake during follow-up. Normalisation of [(18)F]FDG uptake correlated with clinical improvement and with normalisation of the laboratory findings. All except one of the patients with positive aortic [(18)F]FDG uptake were investigated with MRI and MRA. Thirteen of these 14 patients showed inflammation in at least one vascular region. Of 76 vascular regions studied, 41 (53%) showed vasculitis on MRI. Of 76 vascular regions studied with both PET and MRI, 47 were concordantly positive or negative on both modalities, 11 were positive on MRI only and 18 were positive on PET only. MRI was performed during follow-up in six patients: of 17 regions with inflammatory changes, 15 regions remained unchanged and two showed improvement. Whole-body [(18)F]FDG PET is valuable in the primary diagnosis of early aortitis. The results of [(18)F]FDG PET and MRI in the diagnosis of aortitis in this study were comparable, but FDG imaging identified more vascular regions involved in the inflammatory process than did MRI. In a limited number of patients [(18)F]FDG PET was more reliable than MRI in monitoring disease activity during immunosuppressive therapy.

[F-18-FDG hybrid camera PET in patients with postoperative fever]. / F-18-FDG-Hybrid-Kamera-PET bei Patienten mit postoperativem Fieber.

AIM: Evaluation of F-18-FDG-hybrid-camera-PET imaging in patients with undetermined postoperative fever (POF). METHODS: Prospective study of 18 patients (9 women, 9 men; age 23-85 years) suffering from POF with 2-fluoro-2'-deoxyglucose (F-18-FDG) using a dual headed coincidence camera (DHCC). Surgery had been performed 5-94 days prior to our investigation. 13 of the 18 patients received antibiotic therapy during the time of evaluation. Ten (55%) had an infectious and eight (45%) a non infectious cause of fever. RESULTS: Increased F-18-FDG-uptake outside the surgical wound occurred in 13 regions (infection n = 11, malignancy n = 2). The sensitivity of F-18-FDG-hybrid-camera-PET in imaging infection in areas outside the surgical wound was 86% and the specificity 100%, respectively. Antibiotic therapy did not negatively influence the results of F-18-FDG-scanning. Increased F-18-FDG-uptake within the surgical wound was seen in 8 of 18 patients. The sensitivity of F-18-FDG-hybrid-camera-PET in imaging infection within the surgical wound was 100% and the specificity 56%, respectively. The interval between surgery and F-18-FDG-scanning was significantly shorter in patients with false positive results compared with patients showing true negative results (median 34 vs. 54 days; p = 0.038). CONCLUSION: In POF-Patients, F-18-FDG transaxial tomography performed with a F-18-FDG-hybrid-camera-PET is sensitive in the diagnosis of inflammation and malignant disease within and outside the surgical wound. Because of the accumulation of the tracer both in granulation tissue and infection, the specificity in detecting the focus of fever within the surgical wound is poor.

Chronic bacterial osteomyelitis: prospective comparison of (18)F-FDG imaging with a dual-head coincidence camera and (111)In-labelled autologous leucocyte scintigraphy.

Indium-111-labelled white blood cells ((111)In-WBCs) are currently considered the tracer of choice in the diagnostic work-up of suspected active chronic osteomyelitis (COM). Previous studies in a limited number of patients, performed with dedicated PET systems, have shown that [(18)F]2'-deoxy-2-fluoro- D-glucose (FDG) imaging may offer at least similar diagnostic accuracy. The aim of this prospective study was to compare FDG imaging with a dual-head coincidence camera (DHCC) and (111)In-WBC imaging in patients with suspected COM. Thirty consecutive non-diabetic patients with possible COM underwent combined skeletal scintigraphy (30/30 patients), (111)In-WBC imaging (28/30 patients) and FDG-PET with a DHCC (30/30 patients). During diagnostic work-up, COM was proven in 11/36 regions of suspected skeletal infection and subsequently excluded in 25/36 regions. In addition, soft tissue infection was present in five patients and septic arthritis in three. (111)In-WBC imaging in 28 patients was true positive in 2/11 regions with proven COM and true negative in 21/23 regions without further evidence of COM. False-positive results occurred in two regions and false-negative results in nine regions suspected for COM. Most of the false-negative results (7/9) occurred in the central skeleton. If the analysis was restricted to the 18 regions with available histology ( n=17) or culture ( n=1), (111)In-WBC imaging was true positive in 2/18 regions, true negative in 8/18 regions, false negative in 7/18 regions and false positive in 1/18 regions. FDG-DHCC imaging was true positive in 11/11 regions with proven COM and true negative in 23/25 regions without further evidence of COM. False-positive results occurred in two regions. If the analysis was restricted to the 19 regions with available histology ( n=18) or culture ( n=1), FDG-DHCC imaging was true positive in 9/9 regions with proven COM and true negative in 10/10 regions without further evidence of COM. It is concluded that FDG-DHCC imaging is superior to (111)In-WBC scintigraphy in the diagnosis of COM in the central skeleton and therefore should be considered the method of choice for this indication. This seems to hold true for peripheral lesions as well, but in our series the number of cases with proven infection was too small to permit a final conclusion.