Variability in PET image quality and quantification measured with a permanently filled 68Ge-phantom: a multi-center study.

BACKGROUND: This study evaluated, as a snapshot, the variability in quantification and image quality (IQ) of the clinically utilized PET [18F]FDG whole-body protocols in Finland using a NEMA/IEC IQ phantom permanently filled with 68Ge. METHODS: The phantom was imaged on 14 PET-CT scanners, including a variety of models from two major vendors. The variability of the recovery coefficients (RCmax, RCmean and RCpeak) of the hot spheres as well as percent background variability (PBV), coefficient of variation of the background (COVBG) and accuracy of corrections (AOC) were studied using images from clinical and standardized protocols with 20 repeated measurements. The ranges of the RCs were also compared to the limits of the EARL 18F standards 2 accreditation (EARL2). The impact of image noise on these parameters was studied using averaged images (AVIs). RESULTS: The largest variability in RC values of the routine protocols was found for the RCmax with a range of 68% and with 10% intra-scanner variability, decreasing to 36% when excluding protocols with suspected cross-calibration failure or without point-spread-function (PSF) correction. The RC ranges of individual hot spheres in routine or standardized protocols or AVIs fulfilled the EARL2 ranges with two minor exceptions, but fulfilling the exact EARL2 limits for all hot spheres was variable. RCpeak was less dependent on averaging and reconstruction parameters than RCmax and RCmean. The PBV, COVBG and AOC varied between 2.3-11.8%, 9.6-17.8% and 4.8-32.0%, respectively, for the routine protocols. The RC ranges, PBV and COVBG were decreased when using AVIs. With AOC, when excluding routine protocols without PSF correction, the maximum value dropped to 15.5%. CONCLUSION: The maximum variability of the RC values for the [18F]FDG whole-body protocols was about 60%. The RC ranges of properly cross-calibrated scanners with PSF correction fitted to the EARL2 RC ranges for individual sphere sizes, but fulfilling the exact RC limits would have needed further optimization. RCpeak was the most robust RC measure. Besides COVBG, also RCs and PVB were sensitive to image noise.

Prolonged exclusive breast-feeding results in low serum concentrations of immunoglobulin G, A and M.

Serum levels of IgG, IgA and IgM were measured in 198 infants at ages 2, 4, 6, 9 and 12 months. By age 9 months 30 infants were still exclusively breast-fed; their IgG and IgM levels were significantly lower than those of infants weaned early to formula (before age 3.5 months). By 12 months 6 infants were still exclusively breast-fed; their IgA levels were by then also similarly lower. There was no significant difference in the number of infections experienced by these groups of infants. After 2 months on formula feeding, the IgG and IgM levels of the infants who were exclusively breast-fed for 9 months had caught up with the levels of the infants weaned early to formula. Only at 12 months of age prealbumin levels of the exclusively breast-fed infants showed a positive correlation to IgG and IgA levels; no correlation was found between immunoglobulin levels and levels of serum iron and zinc.

Identification of mononuclear cells in cell suspension from cutaneous infiltrates freed by a suction blister method.

Mononuclear cells were liberated from superficial skin inflammations by a suction blister method which yielded a sufficient number of cells for histochemical and immunocytochemical analysis. The cell population consisted mainly of T cells which were identified as sheep red blood cell rosettes. Very few B cells were found as rosettes with immunobeads. Macrophages and eosinophils were found in varying numbers and they were identified histochemically. The method is suitable for studying nontumorous skin infiltrates.

The ribonucleic acid (RNA) skin test in systemic lupus erythematosus and other connective tissue diseases.

A series of 65 patients with different autoimmune diseases was examined using different RNA-solutions for intradermal skin tests. Clinically positive results were obtained most often in patients with mixed connective tissue disease but quite often also in patients with systemic lupus erythematosus and progressive systemic sclerosis or with some symptoms of an automimmune nature. The histological examination of the biopsies from the test sites revealed that there was no correlation between the clinically positive tests and the histological criteria usually used as a sign of a positive test.

Gluten-free diet in dermatitis herpetiformis. I. Clinical response of skin lesions in 81 patients.

Eighty-one patients with dermatitis herpetiformis were treated with a gluten-free diet (GFD) for periods varying from 6 to 36 months. At the end of the treatment the daily requirement of dapsone was significantly lower in patients treated with a GFD than in 49 patients on a normal diet. 93% of the patients on a GFD were able to reduce the dose of dapsone whereas only 16% of the patients on a normal diet were able to do this. Complete remissions occurred only in patients on a GFD. 28% of the patients on a GFD were able to stop dapsone completely and were continuously asymptomatic when they observed a strict diet. A response to a GFD was noted on the mean daily requirement of dapsone as soon as the treatment was initiated although the length of time for an individual response varied. After one year on a GFD the patients needed on average about 40% and after 3 years about 20% of the dose required to control skin symptoms at the beginning of the diet. The patients responded to a GFD irrespective of changes found in the jejunal mucosa and irrespective of the presence of absence of HLA-B8.

The liver in sarcoidosis.

Neddle biopsies of the liver were performed in 121 cases of sarcoidosis. Granulomas compatible with sarcoidosis were seen in 24 percent of the cases. Liver function tests (serum alkaline phosphatase, serum aspartate aminotransferase, serum alanine aminotransferase, and bromsulphthalein clearance test) were performed on 325 patients with sarcoidosis and on 132 with non-sarcoid erythema nodosum (EN). Pathological findings were seen especially in patients with extensive EN, without any correlation with the disease responsible for the eruption. Hepatic granulomas were found more often in patients with sarcoid changes in lung parenchyma than in those with bilateral hilar adenitis only. There were no other definite correlations between hepatic granulomas and other clinical and laboratory findings. The incidence of pathological results in this study was clearly lower than, e.g., in the USA, thus reflecting the good prognosis of sarcoidosis in the Scandinavian countries.

The deoxyribonucleic acid (DNA) skin test in systemic lupus erythematosus. I. Clinical evaluation.

A clinical evaluation of the intradermal DNA-test was carried out on a series of patients with untreated or with treated definite systemic lupus erythematosus (SLE), or with suspected SLE with or without circulating antinuclear factors. A saline solution of a commercially available DNA-preparation was used. The course of the DNA reaction was followed for 24-48 h after the injection. All nine cases of untreated definite SLE had a positive DNA test 6 h after the injection, and eight cases a positive result at 24 h. All seven patients with definite SLE who were on low-dosage systemic steroid treatment had a clinically positive. DNA test at 6 h. In all except one of these cases the test was still positive at 24 h. All five patients with definite SLE on antimalarial treatment had a positive test at 6 h which had become negative at 24 h after the injection. Eleven of the twelve patients with suspected SLE and circulating antinuclear factors had a positive DNA test at 6 h, which in nine cases persisted for 24 h. On the other hand, of the eleven ANF negative patients with various connective tissue diseases five had a positive test at 6 h. In only one of these cases it persisted for 24 h. Two of the eighteen control patients with various dermatoses exhibited a positive test at 6 h, and in one of these the positive reaction persisted for 24 h. It is concluded that the intradermal skin test using native DNA is a useful diagnostic tool for the detection of SLE when the reaction is followed up for 24 h. Antimalarial treatment seems to decrease skin reactivity to native DNA.

Isolation of a mycoplasma from sarcoid tissue.

Using a modified cell-free culture medium, a mycoplasma was isolated from sarcoid lymph nodes in two cases and from sarcoid skin lesions in four out of seven cases of chronic sarcoidosis. Growth inhibition tests showed that the isolates were related to Mycoplasma orale type 1. By the indirect haemagglutination method, 244 cases of definite or probable sarcoidosis, 160 patients with other diseases, and 355 blood donors were tested for antibodies against an isolated mycoplasma (strain 215-M). Titres [unk] 16 were found in 14% of the patients with sarcoidosis and in 8% of the patients with other diseases but only in 0.6% of the blood donors. The proportion of patients with high antibody titres among those with sarcoidosis and erythema nodosum was smaller (8%) than among those with other forms of sarcoidosis (17%). The role of the mycoplasmas isolated from sarcoid tissues remains obscure, but it is possible that these organisms are only an expression of altered immunity in sarcoidosis.

Scanning-beam electron microscopy of mycoplasma isolated from rheumatoid arthritis.

Scanning-beam electron microscopic studies on an isolate from definite rheumatoid arthritis are presented.