Sickle cell patients develop splenic dysfunction early in the course of their disease as shown by failure to visualize the organ on technetium‐99m colloid scintigraphy. However, preliminary studies from our center have shown that, when the spleen is not demonstrable on colloid uptake, it may be visualized on technetium‐99m heat‐denatured RBC scintigraphy. With time, however, the spleen can no longer be visualized with both tests in many patients. We have studied 46 patients aged 2 to 16 years, which included 36 SS, 7 Sβ0 thal, and 3 SD. Eighteen (39.1%) had normal splenic colloid uptake (Group 1), 15 (32.6%) had partial uptake (Group 2), and 13 (28.3%) had absent uptake (Group 3). When the patients in Group 1 were compared to those in the two other groups, there was no significant difference in the mean age and Hb F values. However, the mean Hb of 10.2 g/dl in Group 1 was significantly higher than the value of 9.0 g/dl in the other two groups. In addition, 60% of the SS patients with normal uptake and 40% of those with partial or absent uptake had co‐existing α‐thal trait; the difference in this proportion is significant (χ2 = 85, P < 0.0001). Heat‐denatured RBC scintigraphy was carried out on five patients in Group 2, and the spleen was visible in all, while of 12 children in Group 3, the spleen was visible only in 4 patients. This study demonstrates that the phagocytic function of the spleen, which is tested by colloid uptake, is the first to be lost while the filtration function, tested by denatured RBC uptake, persists for much longer. This finding may have significant implications for the clinical symptomatology and therapeutic strategies of sickle cell disease. Am. J. Hematol. 69:23‐27, 2002. © 2002 Wiley‐Liss, Inc.

Our objective in this study was to evaluate whether measurement of quantitative uptake of 99m Tc-methylene diphosphate (MDP) and 99m Tc-hexamethylpropyleneamine oxime (HMPAO) white blood cells (WBCs) is useful in detecting osteomyelitis in peripheral bony lesions. Methods: Twenty-four patients (12 men and 12 women; age range, 25-72 y) were referred for imaging because of clinically suspected osteomyelitis. They had a traumatic fracture (n 5 10), knee prosthesis (n 5 5), hip prosthesis (n 5 2), diabetic foot (n 5 4), or chronic osteomyelitis (n 5 3). Threephase bone scanning and 99m Tc-HMPAO WBC studies were performed on all patients within the same week. Regions of interest were drawn over the abnormal bony sites and the contralateral normal sites, and the abnormal-to-normal uptake ratios (A/N ratios) were obtained for both studies. Results: All patients had abnormal findings on 3-phase bone scanning, whereas 17 (71%) had abnormal findings on 99m Tc-HMPAO WBC studies, of which 15 were confirmed to be true-positive. In those 15 patients, the mean A/N ratios for 99m Tc-MDP and 99m Tc-HMPAO WBC were 3.0 6 1.6 (range, 1.3-6.2) and 1.8 6 0.3 (range, 1.4-2.2), respectively. In the other 9 patients, whose scan results were clinically confirmed to be true-negative, the mean A/N ratios for 99m Tc-MDP and 99m Tc-HMPAO WBC were 2.1 6 1.2 and 1.2 6 0.2, respectively. In the group with a 99m Tc-MDP A/N ratio greater than 2 (n 5 15), 87% (13/15) had a high 99m Tc-HMPAO WBC A/N ratio (.1.5), including 2 that were falsepositive. In the remaining 2 patients, one with chronic osteomyelitis and the other with a recent hip prosthesis, 99m Tc-HMPAO WBC ratios were normal. In the group with a bone A/N ratio of less than 2 (n 5 9), only 4 patients (44%) were true-positive for acute osteomyelitis. Conclusion: 99m Tc-MDP bone scanning alone, with an A/N ratio of more than 2, is useful in detecting osteomyelitis in violated bone except in the case of a recent hip prosthesis or chronic osteomyelitis.

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