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We review recent technological advances and new clinical indications for sentinel node (SN) and radioguided surgery in order to delineate future tendencies of interventional nuclear medicine in this field. A literature research was performed in PubMed to select relevant articles to be used as key references for analysis of the current approaches and tendencies in SN and radioguided surgery, as well as the evolving contribution of nuclear medicine intervention techniques to the various clinical applications. For classic indications such as melanoma and breast cancer, the incorporation of the SN approach based on the combined use of existing and new preoperative and intraoperative technologies in high-risk patient categories is becoming an emerging area of clinical indication. For SN biopsy staging in other malignancies with more complex lymphatic drainage, the incorporation of sophisticated tools is most helpful. The consecutive use of PET/CT and the SN procedure is increasing as a potential combined approach for the management of specific areas such as the axilla and the pelvis in patients at high risk of regional dissemination. Also, for the management of locoregional metastasis and oligometastatic disease, interventional nuclear medicine techniques are becoming valuable alternatives. The extended experience with SN biopsy is leading to technological advances facilitating the incorporation of this procedure to stage other malignancies with complex lymphatic drainage. New nuclear medicine-based approaches, incorporating SPECT/CT and PET/CT to guide resection of SNs and occult metastases, have recently been gaining ground.

Aims/hypothesis: Brown adipose tissue (BAT) improves energy metabolism by combusting glucose and lipids into heat. Agonism of the glucagon-like peptide-1 receptor (GLP-1R) within the central nervous system activates BAT in mice. Moreover, in patients with type 2 diabetes, GLP-1R agonism lowers body weight and improves glucose and lipid levels, possibly involving BAT activation. Interestingly, people from South Asian descent are prone to develop cardiometabolic disease. We studied the effect of GLP-1R agonism on BAT in humans, specifically in South Asians and Europids without obesity or type 2 diabetes. Methods: Twelve Dutch South Asian and 12 age- and BMI-matched Europid nondiabetic men received 12 weeks extended-release exenatide (Bydureon) in this single-arm prospective study. Before and after treatment, BAT was visualized by a cold-induced [18F]FDG-PET/CT scan and a thermoneutral MRI scan, and resting energy expenditure (REE), substrate oxidation, body composition and fasting plasma glucose and serum lipids were determined. Appetite was rated using a visual analogue scale. Results: Since the effect of exenatide on metabolic parameters did not evidently differ between ethnicities, data of all participants were pooled. Exenatide decreased body weight (−1.5 ± 0.4 kg, p < 0.01), without affecting REE or substrate oxidation, and transiently decreased appetite ratings during the first weeks. Exenatide also lowered triglycerides (−15%, p < 0.05) and total cholesterol (−5%, p < 0.05), and tended to lower glucose levels. Notably, exenatide increased BAT metabolic volume (+28%, p < 0.05) and mean standardized uptake value (+11%, p < 0.05) ([18F]FDG-PET/CT), without affecting supraclavicular adipose tissue fat fraction (MRI). Conclusions/interpretation: We show for the first time that GLP-1R agonism increases [18F]FDG uptake by BAT in South Asian and Europid men without obesity or type 2 diabetes. Trial registry: Clinicaltrials.gov NCT03002675.

The axillary lymph node status remains a major prognostic factor in early-stage breast cancer, providing information that is important for tailoring postsurgical treatment. Sentinel lymph node biopsy (SLNB) has radically altered the management of the axilla for patients with early breast cancer, resulting in fewer complications and better quality of life than de novo axillary lymph node dissection. Although SLNB is widely performed in patients with breast cancer, several technical issues such as the choice of the optimal radiopharmaceutical, the site and mode of radiocolloid injection, and the type of preoperative imaging remain a matter of discussion. With optimal preoperative lymphatic mapping high identification rates are achieved, especially when the radiocolloid is combined with blue dye. The performance of SLNB can be further improved with the intraoperative use of portable imaging devices and hybrid approaches, especially in cases of complex drainage. The SLNB procedure is indicated in patients with early-stage breast cancer (cT1-2 tumors) without cytological or histological evidence of axillary lymph node metastases. Controversies remain concerning the application of SLNB in patients with large or multifocal tumors, ductal carcinoma in situ, and recurrent disease. In addition, no consensus exists about the importance of identification and treatment of metastasis in lymph nodes of the internal mammary chain. With the increasing use of neoadjuvant chemotherapy for breast-sparing surgery in patients with locally advanced breast cancer, a new dilemma has arisen concerning appropriate timing of the SLNB procedure in the neoadjuvant setting. The abovementioned issues are discussed in detail in this chapter. In addition, the chapter considers the clinical impact of the SLNB procedure in breast cancer, including the ongoing paradigm shift in axillary management.

PurposeRecent developments in iterative image reconstruction enable absolute quantification of SPECT/CT studies by incorporating compensation for collimator-detector response, attenuation, and scatter as well as resolution recovery into the reconstruction process (Evolution; Q.Metrix package; GE Healthcare, Little Chalfont, UK). The aim of this experimental study is to assess its quantitative accuracy for potential clinical Tc-99m-sestamibi (MIBI)-related SPECT/CT application in neoadjuvant chemotherapy response studies in breast cancer.MethodsTwo phantoms were filled with MIBI and acquired on a SPECT/CT gamma camera (Discovery 670 Pro; GE Healthcare), that is, a water cylinder and a NEMA body phantom containing six spheres that were filled with an activity concentration reflecting clinical MIBI uptake. Subsequently, volumes-of-interest (VOI) of each sphere were drawn (semi)automatically on SPECT using various isocontour methods or manually on CT. Finally, prone MIBI SPECT/CT scans were acquired 5 and 90 min p.i. in a locally advanced breast cancer patient.ResultsActivity concentration in the four largest spheres converged after nine iterations of evolution. Depending on the count statistics, the accuracy of the reconstructed activity concentration varied between -4.7 and -0.16% (VOI covering the entire phantom) and from 6.9% to 10% (8.8 cm ? cylinder VOI placed in the center of the phantom). Recovery coefficients of SUVmax were 1.89 0.18, 1.76 +/- 0.17, 2.00 +/- 0.38, 1.89 +/- 0.35, and 0.90 +/- 0.26 for spheres with 37, 28, 22, 17, and 13 mm ?, respectively. Recovery coefficients of SUVmean were 1.07 +/- 0.06, 1.03 +/- 0.09, 1.17 +/- 0.21, 1.10 +/- 0.20, and 0.52 +/- 0.14 (42% isocontour); 1.10 +/- 0.07, 1.02 +/- 0.09, 1.13 +/- 0.19, 1.06 +/- 0.19, and 0.51 +/- 0.13 (36% isocontour with local background correction); and 0.96, 1.09, 1.03, 1.03, and 0.29 (CT). Patient study results were concordant with the phantom validation.ConclusionsAbsolute SPECT/CT quantification of breast studies using MIBI seems feasible (

Breast cancer (BC) is the most common cancer in women worldwide. In the last years, the contribution of nuclear medicine has grown based on the use of dedicated molecular breast devices for diagnosis and biopsy. Recent technical improvements have been achieved in order to increase the detection of smaller breast lesions using lower doses of radiotracers as well as to facilitate accurate biopsy sampling. Furthermore, new prototypes have been developed combining anatomic and functional imaging. Although the gamma-emitting 99m Tc-sestamibi ( 99m Tc-MIBI) and the positron-emitting 18 F-fluorodeoxyglucose ( 18 F-FDG) are the most widely used radiotracers, several new tracers have been investigated to target more specific biologic features of BC like proliferation, angiogenesis and tumour receptor status. Dedicated molecular breast devices have been introduced as an adjunct imaging tool to mammography (MG) and ultrasound (US) in the clinical work-up for BC. Additionally, due to the increased interest in molecular tumour subtype analysis and ribonucleic acid (RNA)-based gene expression profiling tests in the routine clinical practice, a possible new clinical application of dedicated breast imaging concerns locally advanced BC, principally in order to visualise intra-tumour metabolic heterogeneity enabling selection of areas with highest tracer uptake (vital tissue) for core needle biopsy. Hence, it will be possible to more adequately tailor the individual treatment, also enabling therapy response monitoring. This review evaluates the current and future perspectives as well as the shortcomings of breast imaging using dedicated nuclear medicine devices.

Purpose: To investigate the clinical utility of molecular breast imaging (MBI) in patients with proven invasive breast cancer scheduled for breast-conserving surgery (BCS). Methods: Following approval by the institutional review board and written informed consent, records of patients with newly diagnosed breast cancer scheduled for BCS who had undergone MBI for local staging in the period from March 2012 till December 2014 were retrospectively reviewed. Results: A total of 287 women (aged 30–88 years) were evaluated. MBI showed T stage migration in 26 patients (9%), with frequent detection of in situ carcinoma around the tumor. Surgical management was adjusted in 14 of these patients (54%). In 17 of 287 patients (6%), MBI revealed 21 proven additional lesions in the ipsilateral, contralateral breast or both. In 18 of these additional foci (86%), detected in 15 patients, malignancy was found. Thirteen of these 15 patients had ipsilateral cancer and 2 patients bilateral malignancy. In total, MBI revealed a larger tumor extent, additional tumor foci or both in 40 patients (14%), leading to treatment adjustment in 25 patients (9%). Conclusion: MBI seems to be a useful imaging modality with a high predictive value in revealing ipsilateral and bilateral disease not visualized by mammography and ultrasound. It may play an important role in delineating the extent of the index lesion during preoperative planning. Incorporation of MBI in the clinical work-up as an adjunct modality to mammography and ultrasound may lead to better selection of patients who could benefit from BCS.

OBJECTIVE. The purpose of this study is to evaluate a new device using molecular breast imaging (MBI) for 99mTc-sestamibi-guided stereotactic lesion localization as a complementary biopsy tool. MATERIALS AND METHODS. From December 2012 to May 2016, a total of 38 consecutive women (mean age, 59 years; range, 41-77 years) underwent 99mTc-sestamibi-guided biopsy using a new MBI-based device and were retrospectively reviewed. The biopsy modality used five steps: Stereotactic localization of the 99mTc-sestamibi-avid lesion, calculation of coordinates of the lesion location using dedicated software, placement of the needle, verification of the correct needle position, and tissue sampling with a vacuum-assisted device followed by placement of a radiologic marker at the biopsy site and ex vivo measurement of the biopsy specimens. RESULTS. The procedure was technically successful in all 38 lesions. In all cases, biopsy samples were radioactive and adequate for histopathologic analysis. Nineteen lesions (50%) were found to be malignant, and the remaining lesions were found to be benign. The mean procedure time was 71 minutes (range, 44-112 minutes). The radiologic marker was successfully deployed in 37 lesions (97%). Two hematomas and three vasovagal reactions were observed. CONCLUSION. Technetium-99m sestamibi-guided biopsy performed using a dedicated MBI-based device is technically feasible and represents a valuable complementary biopsy tool in breast lesion diagnosis.

This case highlights the use of lymphoscintigraphy with SPECT/CT in patients with previous chest and/or axillary surgery. A 67-year-old woman with a history of left breast carcinoma treated with lumpectomy and radiotherapy, and a second lumpectomy of the ipsilateral breast for a second breast carcinoma, underwent a lymphoscintigraphy for a new left breast lesion. Planar images visualized an alternative lymphatic drainage to the contralateral axilla and to the left paravertebral area. SPECT/CT confirmed sentinel nodes in both stations.

This study investigated whether radiomic features derived from preoperative PET images could predict both tumor biology and prognosis in women with invasive squamous cell carcinoma of the vulva. Methods: Patients were retrospectively included if they had a unifocal primary cancer at least 2.6 cm in diameter, received a preoperative 18F-FDG PET/CT scan followed by surgery, and had at least 6 mo of follow-up data. 18F-FDG PET images were analyzed by semiautomatically drawing a volume of interest on the primary tumor in each PET image, followed by extraction of 83 radiomic features. Unique radiomic features were identified by principal-component analysis (PCA), after which they were compared with histopathology using nonpairwise group comparison and linear regression. Univariate and multivariate Cox regression analyses were used to correlate the identified features with progression-free survival (PFS) and overall survival (OS). Survival curves were estimated using the Kaplan–Meier method. Results: Forty women were included. PCA revealed 4 unique radiomic features, which were not associated with histopathologic characteristics such as grade, depth of invasion, lymph-vascular space invasion, and metastatic lymph nodes. No statistically significant correlation was found between the identified features and PFS. However, Moran’s I, a feature that identifies global spatial autocorrelation, correlated with OS (P = 0.03). Multivariate Cox regression analysis showed that extracapsular invasion of the metastatic lymph nodes and Moran’s I were independent prognostic factors for PFS and OS. Conclusion: Our data show that PCA is usable to identify specific radiomic features. Although the identified features did not correlate strongly with tumor biology, Moran’s I was found to predict patient prognosis. Larger studies are required to establish the clinical relevance of the observed findings.

In breast cancer, interest in technetium-99m (Tc-99m) sestamibi-based therapy monitoring is increasing owing to the growing use of Tc-99m-sestamibi-based molecular breast imaging. In the present meta-analysis of 529 patients, Tc-99m-sestamibi planar imaging showed low sensitivity for predicting a pathologic nonresponse to neoadjuvant chemotherapy. In contrast, Tc-99m-sestamibi imaging performed during treatment seemed highly sensitive for the prediction of nonresponse. New tools incorporating quantitative single photon emission computed tomography/computed tomography need to be explored.Background: Interest in technetium-99m (Tc-99m)-sestamibi imaging for neoadjuvant chemotherapy (NAC) response monitoring in locally advanced breast cancer (LABC) is increasing but remains matter of discussion. The present study conducted a meta-analysis of the diagnostic performance of Tc-99m-sestamibi to predict pathologic nonresponse to NAC for primary LABC. Materials and Methods: A systematic data search was performed. Studies with a minimum of 10 LABC patients that had evaluated Tc-99m-sestamibi imaging for NAC nonresponse using conventional planar scintimammography, breast-specific gamma-imaging, and/or single photon emission computed tomography/computed tomography (SPECT/CT) were included. The histopathologic findings were the reference standard. The meta-analysis was performed using a mixed logistic regression model. Results: The search revealed 14 eligible studies with 529 patients. Of the 14 studies, 11 had evaluated scintimammography and 3 breast-specific gamma-imaging. No studies examining SPECT or SPECT/CT were found. The overall estimated pooled sensitivity, specificity, and positive and negative likelihood ratios of Tc-99m-sestamibi imaging to predict nonresponsiveness to NAC were 70.3% (95% confidence interval [CI], 56.5%-81.3%%), 90.1% (95% CI, 77.5%-96.0%), 7.13 (95% CI, 3.08-16.53), and 0.33 (95% CI, 0.22-0.49), respectively. Only 3 studies (107 patients) evaluated Tc-99m-sestamibi imaging during NAC, reported an estimated pooled sensitivity of 87% (95% CI, 72%-100%) and specificity of 93% (95% CI, 85%-100%). Conclusion: Only planar Tc-99m-sestamibi imaging has been investigated for NAC nonresponse in LABC but showed low sensitivity to predict pathologic nonresponse. However, most studies focused on the prediction of pathologic complete response after NAC. Although experience is limited, Tc-99m-sestamibi uptake during NAC seems highly sensitivity for the prediction of nonresponsiveness. Features such as SPECT/CT imaging, standardized quantification, relation to tumor subtypes, and proper timing have been insufficiently evaluated and require further investigation. (C) 2017 Elsevier Inc. All rights reserved.

The aim of this study was to evaluate the effect of sitagliptin on glucose tolerance, plasma lipids, energy expenditure and metabolism of brown adipose tissue (BAT), white adipose tissue (WAT) and skeletal muscle in overweight individuals with prediabetes (impaired glucose tolerance and/or impaired fasting glucose). One participant from the sitagliptin group was excluded from analysis, due to a distribution error, leaving 29 participants for further analysis. Sitagliptin, but not placebo, lowered glucose excursion (−40%; p < 0.003) during OGTT, accompanied by an improved insulinogenic index (+38%; p < 0.003) and oral disposition index (+44%; p < 0.003). In addition, sitagliptin lowered serum concentrations of triacylglycerol (−29%) and very large (−46%), large (−35%) and medium-sized (−24%) VLDL particles (all p < 0.05). Body weight, body composition and energy expenditure did not change. In skeletal muscle, sitagliptin increased mRNA expression of PGC1β (also known as PPARGC1B) (+117%; p < 0.05), a main controller of mitochondrial oxidative energy metabolism. Although the primary endpoint of change in BAT volume and activity was not met, sitagliptin increased [18F] FDG uptake in subcutaneous WAT (sWAT; +53%; p < 0.05). Reported side effects were mild and transient and not necessarily related to the treatment. Twelve weeks of sitagliptin in overweight, Europid men with prediabetes improves glucose tolerance and lipid metabolism, as related to increased [18F] FDG uptake by sWAT, rather than BAT, and upregulation of the mitochondrial gene PGC1β in skeletal muscle. Studies on the effect of sitagliptin on preventing or delaying the progression of prediabetes into type 2 diabetes are warranted., This work was supported in part by a research grant to PCNR fromthe Investigator Initiated Studies Programof Merck Sharp&Dohme Corp (IIS no. 51292). PCNR is an Established Investigator of the Dutch Heart Foundation (grant 2009T038). MRB is supported by a Dutch Diabetes Research Foundation Fellowship (grant 2015.81.1808). This collaboration project is also supported in part by the Ministry of Economic Affairs by means of the PPP Allowance made available by the Top Sector Life Sciences & Health to stimulate public–private partnerships. BMT and JRR are supported by University of Granada, Plan Propio de Investigacion 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES). This work was also supported by the Netherlands CardioVascular Research Initiative: ‘the Dutch Heart Foundation, Dutch Federation of University Medical Centers, the Netherlands Organisation for Health Research and Development and the Royal Netherlands Academy of Sciences’ for the GENIUS-II project ‘Generating the best evidence-based pharmaceutical targets for atherosclerosis’ (CVON2017-20).

Introduction Brown adipose tissue (BAT) recently emerged as a potential therapeutic target in the treatment of obesity and associated disorders due to its fat-burning capacity. The current gold standard in assessing BAT activity is [18F]FDG PET-CT scan, which has severe limitations including radiation exposure, being expensive, and being labor-intensive. Therefore, indirect markers are needed of human BAT activity and volume. Objective We aimed to identify metabolites in serum that are associated with BAT volume and activity in men. Methods We assessed 163 metabolites in fasted serum of a cohort of twenty-two healthy lean men (age 24.1 (21.7–26.6) years, BMI 22.1 (20.5–23.4) kg/m2) who subsequently underwent a cold-induced [18F]FDG PET-CT scan to assess BAT volume and activity. In addition, we included three replication cohorts consisting of in total thirty-seven healthy lean men that were similar with respect to age and BMI compared to the discovery cohort. Results After correction for multiple testing, fasting concentrations of lysophosphatidylcholine-acyl (LysoPC-acyl) C16:1, LysoPC-acyl C16:0 and phosphatidylcholine-diacyl C32:1 showed strong positive correlations with BAT volume (β= 116 (85–148) mL, R2 = 0.81, p = 4.6 × 10−7 ; β = 79 (93–119) mL, R2 = 0.57, p = 5.9 × 10−4 and β= 91 (40–141) mL, R2 = 0.52, p = 1.0 × 10−3, respectively) as well as with BAT activity (β= 0.20 (0.11–0.29) g/mL, R2 = 0.59, p = 1.9 × 10−4; β = 0.15 (0.06–0.23) g/mL, R2 = 0.47, p = 2.0 × 10−3 and β= 0.13 (0.01–0.25) g/mL, R2 = 0.28, p = 0.04, respectively). When tested in three independent replication cohorts (total n = 37), the association remained significant between LysoPC-acyl C16:0 and BAT activity in a pooled analysis (β= 0.15 (0.07–0.23) g/mL, R2 = 0.08, p = 4.2 × 10−4). Conclusions LysoPC-acyl C16:0 is associated with BAT activity in men. Since BAT is regarded as a promising tool in the battle against obesity and related disorders, the identification of such a noninvasive marker is highly relevant. Electronic supplementary material The online version of this article (doi:10.1007/s11306-017-1185-z) contains supplementary material, which is available to authorized users.

BACKGROUND: Individuals of south Asian origin have a very high risk of developing type 2 diabetes compared with white Caucasians. We aimed to assess volume and activity of brown adipose tissue (BAT), which is thought to have a role in energy metabolism by combusting fatty acids and glucose to produce heat and might contribute to the difference in incidence of type 2 diabetes between ethnic groups. METHODS: We enrolled Dutch nationals with south Asian ancestry and matched Caucasian participants at The Rijnland Hospital (Leiderdorp, Netherlands). Eligible participants were healthy lean men aged 18-28 years, and we matched groups for BMI. We measured BAT volume and activity with cold-induced (18)F-fluorodeoxyglucose ((18)F-FDG) PET CT scans, and assessed resting energy expenditure, non-shivering thermogenesis, and serum parameters. This study is registered with the Netherlands Trial Register, number 2473. FINDINGS: Between March 1, 2013, and June 1, 2013, we enrolled 12 participants in each group; one Caucasian participant developed hyperventilation after (18)F-FDG administration, and was excluded from all cold-induced and BAT measurements. Compared with Caucasian participants, south Asian participants did not differ in age (mean 23.6 years [SD 2.8] for south Asians vs 24.6 years [2.8] for Caucasians) or BMI (21.5 kg/m(2) [2.0] vs 22.0 kg/m(2) [1.6]), but were shorter (1.74 m [0.06] vs 1.85 m [0.04]) and lighter (65.0 kg [8.5] vs 75.1 kg [7.2]). Thermoneutral resting energy expenditure was 1297 kcal per day (SD 123) in south Asian participants compared with 1689 kcal per day (193) in white Caucasian participants (difference -32%, p=0.0008). On cold exposure, shiver temperature of south Asians was 2.0 degrees C higher than Caucasians (p=0.0067) and non-shivering thermogenesis was increased by 20% in white Caucasians (p

The rising incidence of tuberculosis worldwide means an increasing burden on diagnostic facilities, so tests simpler than Ziehl-Neelsen staining are needed. Such tests should be objective, reproducible, and have at least as good a detection limit as 10 4 bacteria/ml. A capture enzyme-linked immunosorbent assay (ELISA) was developed for detection of lipoarabinomannan (LAM) in human sputum samples. As a capture antibody, we used a murine monoclonal antibody against LAM, with rabbit antiserum against Mycobacterium tuberculosis as a source of detector antibodies. The sensitivity of the capture ELISA was evaluated by using purified LAM and M. tuberculosis whole cells. We were able to detect 1 ng of purified LAM/ml and 10 4 M. tuberculosis whole cells/ml. LAM could also be detected in culture filtrate of a 3-week-old culture of M. tuberculosis . The culture filtrate contained approximately 100 μg of LAM/ml. The detection limit in sputum pretreated with N -acetyl- l -cysteine and proteinase K was 10 4 M. tuberculosis whole cells per ml. Thirty-one (91%) of 34 sputum samples from 18 Vietnamese patients with tuberculosis (32 smear positive and 2 smear negative) were positive in the LAM detection assay. In contrast, none of the 25 sputum samples from 21 nontuberculous patients was positive. This specific and sensitive assay for the detection of LAM in sputum is potentially useful for the diagnosis of tuberculosis.

Buruli ulcers have not been previously described in China, and only once at higher latitudes on the northern hemisphere. A patient who travelled in the Shan Dong Province in the People's Republic of China developed an ulcer which was proven to be a Buruli ulcer. The clinical picture and histopathological findings from biopsy specimens are characteristic for a Buruli ulcer, and also the growth in culture (Coletsos medium) at a restricted temperature of 30 degrees C. A multiplex polymerase chain reaction (PCR) based on the amplification of the gene encoding for 16S ribosomal RNA and a nested PCR based on the Mycobacterium ulcerans specific repeated sequence 2404 were performed. These PCR investigations identified the bacteria as M. ulcerans, subspecies shinshuense. The patient was initially treated with clarithromycin and rifampicin, which was changed to ciprofloxacin and rifabutin when rifampicin resistance of the first isolate was established. There were no signs of reactivation of the disease 6 months after the end of treatment. M. ulcerans infection occurs above 30 degrees latitude on the northern hemisphere in China and is caused by M. ulcerans, subspecies shinshuense. This case appears to be cured by chemotherapy alone, in contrast to the general experience that surgical treatment is indicated. The granulomatous reaction with only fragments of acid-fast bacteria in the biopsy at the end of treatment many indicate the development of an adequate cell-mediated immune response leading to resistance to the infection.

Much is known about specific antibodies and their titers in patients with tuberculosis. However, little is known about the avidity of these antibodies or whether changes in avidity occur during the progression of the disease or during treatment. The aims of this study were to determine the avidity of antibodies to Mycobacterium tuberculosis in patients with pulmonary tuberculosis, to explore the value of avidity determination for the diagnosis of tuberculosis, and to study changes in levels of antibodies and their avidity during treatment. Antibody avidity was measured by an enzyme-linked immunosorbent assay with thiocyanate elution. Avidity indices and serum levels of immunoglobulin G to M . tuberculosis were determined for 22 patients with pulmonary tuberculosis before and during treatment and for 24 patients with other pulmonary diseases. Antibody levels and avidity were both significantly higher in untreated tuberculosis patients than in the controls. Avidity determination had more diagnostic potential than determination of the antibody levels. Tuberculosis patients with a long duration of symptoms had higher antibody avidity than those with a recent onset of symptoms, indicating affinity maturation of specific antibodies during active disease. In the early phase of treatment, a decrease in antibody avidity was observed for 73% of all tuberculosis patients, accompanied by an initial increase in antibody levels in 36% of these patients. These phenomena could be explained by an intense stimulation of the humoral response by antigens released from killed bacteria, reflecting early bactericidal activity of antituberculous drugs leading to the production of low-affinity antibodies against these released antigens.

The serodiagnosis of tuberculosis has long been the subject of investigation, but we still lack a test with widespread clinical utility. The poor sensitivity and specificity of commercial assays precludes their use as the sole means of diagnosis. All of these assays use mycobacterial antigens adsorbed onto a surface. Little attention has been paid to changes in antigen conformation that may occur as a result of passive coating of these antigens to solid supports like polystyrene. Such changes may cause technical artifacts resulting in false-positive (FP) and false-negative (FN) reactions. We have developed two different enzyme-linked immunosorbent assay (ELISA) systems, in which human serum antibodies and target antigens of Mycobacterium tuberculosis are able to associate and dissociate freely in solution to form immune complexes. In one ELISA, rabbit antibodies against M tuberculosis, passively coated in the ELISA wells, capture the immune complexes (ICs). In the other ELISA, the ICs are detected by these same rabbit antibodies but are first captured by passively coated goat anti-rabbit IgG. We have compared these two ELISA systems with an ELISA using M tuberculosis antigens passively adsorbed to the solid polystyrene surface of the plate. We studied sera from 81 patients with tuberculosis and 47 healthy subjects. The differences between tuberculosis (TB) patients and healthy subjects were statistically significant in all three of our ELISA systems. However, the ELISA systems using soluble M tuberculosis antigens distinguished better between TB patients and healthy subjects than the ELISA using surface-adsorbed M tuberculosis antigens. We suggest that in the latter ELISA, passive adsorption of the target antigens induces conformational change, generating altered epitopes that are recognized by antibodies present in the serum from even healthy people. These altered conformational epitopes are recognized by antibodies that were originally evoked by antigens other than M tuberculosis, known as heterophile antigens. (C) 2003 Elsevier B.V. All rights reserved