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Liver regeneration and restoration of liver function were studied in six patients who underwent partial hepatectomy with removal of 30-70% of the liver. Liver volume and liver regeneration were studied by single-photon computed tomography (SPECT), using 99mTc-colloid as tracer. The method was assessed in 11 patients by comparing the pre- and post-operative volume measurements with the volume of the resected liver mass. The correlation coefficient between these methods was 0.899 (P less than 0.01). Liver function was determined by measuring the galactose elimination capacity and the caffeine clearance. After a postoperative follow-up period of 50 days the liver had regenerated maximally to a volume of 75 +/- 2% of the preoperative liver mass. Maximal restoration of liver function was achieved 120 days after operation and amounted to 75 +/- 10% for the caffeine clearance and to 100 +/- 25% for the galactose elimination capacity. This study shows that SPECT is a useful method for assessing liver regeneration in patients after partial hepatectomy. Our study furthermore shows that caffeine clearance correlates well with total liver volume, whereas the galactose elimination capacity overestimates total liver volume after partial hepatectomy.

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Rheumatoid arthritis (RA) involves the accumulation of monocytederived macrophages in the affected synovial tissue. This process of cell migration could be portrayed scintigraphically to monitor noninvasively the effects of therapy on the progress of the disease. For this purpose, labeling of purified autologous monocytes with 99m Tc-hexamethylpropyleneamine oxime ( 99m Tc-HMPAO) at very high specific radioactivity has recently been developed. The aim of this study was to assess the biodistribution and radiation dosimetry of 99m Tc-HMPAO-labeled monocytes in adult patients with RA. Methods: In 8 patients with RA, monocytes were isolated from 100 mL of blood and labeled with 99m Tc-HMPAO to a yield of 10 Bq/cell. Multiple whole-body scans were performed up to 20 h after reinjection of an average of 200 MBq of 99m Tc-HMPAO-labeled monocytes. Urine and blood samples were collected. The fraction of administered activity in 7 source organs was quantified from the attenuation-corrected geometric mean counts in conjugate views. Radiation-absorbed doses were estimated with OLINDA/EXM software. Results: Autologous monocytes labeled with 99m Tc-HMPAO at high intracellular yields showed in vivo kinetics comparable with labeled leukocytes, with initial trapping in the lungs followed by distribution into the liver, spleen, and bone marrow. The radiation-absorbed estimates for 99m Tc-HMPAO-labeled monocytes were comparable with those for 99m Tc-HMPAOlabeled mixed white blood cells, with an effective dose of 0.011 mSv/MBq. Conclusion: 99m Tc-HMPAO-labeled monocytes have biodistribution and radiation dosimetry similar to those of 99m Tc-HMPAO-labeled mixed white blood cells and might therefore be used for in vivo monitoring of immunomodulating therapy in patients with RA.Key Words: joint/muscle; radiobiology/dosimetry; radiopharmaceuticals; biodistribution; monocytes; rheumatoid arthritis Nucl Med 2008; 49:1380 49: -1385 49: DOI: 10.2967 Rheumat oid arthritis (RA) is a chronic inflammatory disease affecting synovial tissue in multiple joints. Monocytederived macrophage cells accumulate in the inflamed synovium and thereby contribute to the perpetuation of inflammation and destruction of the affected joints (1). Reduced migration of inflammatory cells such as monocytes or macrophages into the synovial compartment or a decrease in the retention of these cells at the site of inflammation may be attained by treatment of patients with antibodies against tumor necrosis factor-a (TNF-a) (2) or perhaps with chemokine receptor antagonists (3). JFor noninvasive monitoring of treatment, migration of cells toward sites of inflammation in vivo can be portrayed scintigraphically after radiolabeling of the cells in vitro with 99m Tc-labeled hexamethylpropyleneamine oxime (HMPAO). Therefore, labeling of purified autologous monocytes with 99m Tc-HMPAO at very high specific radioactivity has recently been developed (4).In this study, the biodistribution and radiation dosimetry of 99m Tc-HMPAO-labeled monocytes were assessed in adult patients w...

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