Diagnostic performance of 123I-labeled serum amyloid P component scintigraphy in patients with amyloidosis.

PURPOSE: To assess the diagnostic accuracy and additional information provided by 123I-labeled serum amyloid P component (SAP) scintigraphy in patients with systemic and localized amyloidosis. SUBJECTS AND METHODS: 123I-labeled human SAP was injected intravenously into 20 controls and 189 consecutive patients with histologically proven amyloidosis: of AA type in 60 cases, AL type in 80, hereditary ATTR type in 27, and localized amyloidosis in 22 cases. SAP scintigrams were obtained 24 hours after tracer injection and were analyzed for abnormal patterns of uptake. Sensitivity and specificity were determined, and scintigraphic findings were compared with clinical data. RESULTS: Diagnostic sensitivity of SAP scintigraphy for systemic AA, AL, and ATTR amyloidosis was 90%, 90%, and 48% respectively, and specificity was 93%. The distribution of amyloid was less diverse in AA than in AL type. Myocardial uptake was not visualized in any patient. Splenic amyloid was very frequent (80%) in AA and AL type but rarely detected clinically (14%). Abnormal tracer uptake in the liver and kidneys correlated with disturbed liver function and proteinuria, respectively. Bone marrow uptake was specific for AL (21%) and was more frequent in AL kappa than AL lambda. Localized amyloid deposits were not imaged. CONCLUSION: SAP scintigraphy is diagnostic of amyloid in most patients with AA and AL type but fewer with hereditary ATTR type, relating to differing distributions and burdens of amyloid in these disorders. It usually reveals more widespread organ involvement than is identified clinically, and certain distributions of amyloid are characteristic of particular fibril types.

Diagnostic I-131 scintigraphy in patients with differentiated thyroid cancer: no additional value of higher scan dose.

OBJECTIVE: After initial treatment with total thyroidectomy and radioiodine ablation, most follow-up protocols for patients with differentiated thyroid carcinoma contain cyclic diagnostic I-131 imaging and serum thyroglobulin measurements. The applied diagnostic I-131 doses vary between 37 and 370 MBq. The aim of this study was to determine the yield of a diagnostic scan with 370 MBq I-131 in patients with a negative diagnostic scan with 74 MBq I-131. METHODS: Retrospective evaluation of 158 patients who received a high-dose diagnostic scan with 370 MBq I-131 because of a negative low-dose diagnostic scan with 74 MBq I-131. Special attention was paid to the patients with positive high-dose diagnostic scanning and undetectable serum thyroglobulin levels after thyroid hormone withdrawal. RESULTS: In 127 (80%) of patients the 370 MBq I-131 scan was negative, just like the preceding low-dose scan. In 31 (20%) of patients abnormal uptake was present on the 370 MBq diagnostic scan. In 19 of these 31 patients serum thyroglobulin was undetectable. In 15/19 the high-dose diagnostic scan proved either false positive or demonstrated clinically irrelevant minor ablation rests. In only four patients (2.5%) did the high-dose diagnostic scans reveal possibly relevant uptake caused by residual differentiated thyroid cancer. CONCLUSION: In 98% of patients a 370 MBq dose of I-131 for diagnostic WBS had no additional value. The combination of a low-dose diagnostic I-131 scan using only 74 MBq combined with a serum Tg level measurement proved sufficient for correct clinical decision making regarding whether the patient requires additional I-131 therapy.

Better yield of (18)fluorodeoxyglucose-positron emission tomography in patients with metastatic differentiated thyroid carcinoma during thyrotropin stimulation.

To determine whether (18)fluorodeoxyglucose-positron emission tomography (FDG-PET) for the detection of recurrences or metastases of differentiated thyroid carcinoma should be performed during thyrotropin (TSH) suppression or TSH stimulation, eight patients were studied sequentially. After the second FDG-PET scan, a therapeutic (131)I dose was administered with posttherapy scans obtained 10 days later. Both FDG-PET scans were compared with each other and with the (131)I posttherapy whole body scans by two independent observers. Findings were verified using other imaging modalities or biopsies. Median TSH was 0.04 mU/L during TSH suppression and 64 mU/L during TSH stimulation. The FDG-PET scans during TSH suppression showed abnormalities in four patients and the FDG-PET scan during TSH stimulation in five patients. One patient was only positive during TSH stimulation. In two other patients the FDG-PET scan during TSH stimulation clearly identified more lesions, and in all positive patients lesion contrast was better during TSH stimulation. In two patients FDG-PET findings during TSH stimulation led to a change in clinical management. Thus, the performance of FDG-PET during TSH stimulation was either superior or equal to FDG-PET during TSH suppression, but never inferior. To detect metastatic or recurrent differentiated thyroid carcinoma FDG-PET should be performed during hypothyroidism, leading to TSH stimulation.

Value of continuous leakage monitoring with radioactive iodine-131-labeled human serum albumin during hyperthermic isolated limb perfusion with tumor necrosis factor-alpha and melphalan.

BACKGROUND: The aim of this study was to analyze the value of continuous leakage monitoring with radioactive iodine-131-labeled human serum albumin (RISA) in patients treated with hyperthermic isolated limb perfusion with tumor necrosis factor-alpha (TNF alpha) and melphalan. METHODS: Forty-eight patients with melanoma (n = 14) or soft tissue sarcoma (n = 34) of an extremity underwent 51 perfusions. Perfusion was performed at the iliac level in 22 cases, at the popliteal level in 16 cases, at the femoral level in 7 cases, and at the axillary level in 6 cases. Leakage rates and perfusion circuit and systemic levels of TNF alpha, interleukin-6, and C-reactive protein were determined, as were systemic hematological and metabolic profiles and tumor response. RESULTS: The mean isotopically measured leakage was 2.9%. Systemic leakage was < or = 2% in 28 perfusions and >2% in 23 perfusions. The correlation between the maximal monitored leakage and maximal systemic TNF alpha levels was.7114. The area under the curve for TNF alpha in the perfusion circuit, indicating the exposure of the perfused limb to TNF alpha, was 18.7% lower in the >2% leakage group. No significant differences in tumor response were found between groups. The area under the curve for systemic TNF alpha, indicating the exposure of the patient to TNF alpha, was 18.1 times higher in the >2% leakage group, resulting in a significant decrease in leukocyte and platelet count, hyperbilirubinemia, hypocholesterolemia, and proteinemia. No beneficial effect of the systemically leaked TNF and melphalan was seen on the occurrence of distant metastasis during follow-up. There was a significant difference between perfusions performed at the iliac and femoral levels compared with leakage values at the popliteal level. CONCLUSIONS: A good correlation between RISA leakage measurement and TNF alpha exposure during and after hyperthermic isolated limb perfusion with TNF alpha and melphalan was demonstrated. RISA leakage measurement serves as a good guide for the effectiveness of isolation during perfusion. If leakage exceeds the 2% limit during perfusion, less exposure of the tumor-bearing limb to TNF alpha, increased exposure of the patient systemic circulation to TNF alpha, and more systemic side effects can be expected.