Multi-frequency processing (MFP) leads to enhanced image quality (IQ) of radiographs. This study is to determine the effect of third generation MFP (M3) on IQ in comparison to standard second-generation MFP (M2). 20 cadavers were examined and post-processing of radiographs was performed with both M2 and M3. Three readers blinded to the MFP used for each image independently compared corresponding image pairs according to overall IQ and depiction of bony structures and soft tissue (+ 2: notably better > 0: equal > − 2: notably worse). A significant deviation of the median grade from grade 0 (equal) (p < 0.01) for each evaluator A, B and C speaks against an equal image quality of M2- and M3-images. M3-images were categorized with better grades (+ 1, + 2) in 87.7% for overall image quality, in 90.4% for soft tissue and 81.8% for bony structures. M3 images showed significant higher averaged SNR and CNR for all investigated lower extremities than that of M2 images (0.031 < p < 0.049). The newest generation of MFP leads to significantly better depiction of anatomical structures and overall image quality than in images processed with the preceding generation of MFP. This provides increased diagnostic accuracy and further decreased radiation exposure.

BACKGROUND:On 27 June 2017 the Act on new regulation of the law for the protection against the harmful effects of ionizing radiation was passed. One of the main innovations in daily surgical practice in the now legally stipulated provisions is the lowering of the eye lens dose to 20 mSv/year (§§ 78, 212 Radiation Protection Act, StrlSchG). MATERIAL AND METHODS:To estimate the level of exposure of the eye lens to ionizing radiation that is to be expected in the course of surgical interventions, the dose that surgeons receive during surgery was determined. For this, the radiation exposure adjacent to the eye lens was measured using a forehead dosimeter while performing surgical interventions over a period of 8 weeks in 2 different operating rooms. RESULTS:As a result, a mean estimated eye lens radiation dose Hp (3) of 190 µSv could be determined during the 2‑month study period. Thus, the estimated cumulative radiation dose in 1 year of approximately 1.2 mSv was significantly below the threshold of 20 mSv/year. CONCLUSION:By complying with the common radiation protection measures in the context of operative interventions in orthopedics and trauma surgery, the legal limit value of 20 mSv/year is generally not expected to be exceeded.

Am 27.06.2017 wurde das Gesetz zur Neuregelung des Rechts zum Schutz vor der schädlichen Wirkung ionisierender Strahlung verabschiedet. Eine der wesentlichen Neuerungen in der täglichen chirurgischen Praxis in den jetzt gesetzlich festgelegten Bestimmungen stellt die Absenkung der Augenlinsendosis auf 20 mSv/Jahr (§§ 78, 212 StrlSchG) dar. Zur Abschätzung der Höhe der Augenlinsendosis, welche im Rahmen von chirurgischen Eingriffen zu erwarten ist, wurde durch Messung der Strahlendosis in der Nähe der Augenlinsen durch Stirndosimeter über einen Zeitraum von 8 Wochen in 2 unterschiedlichen OP die Augenlinsendosis ermittelt, die beim Operateur/der Operateurin im Zusammenhang mit den durchgeführten Eingriffen zu erwarten ist. Im Ergebnis konnte eine mittlere geschätzte Augenlinsendosis Hp(3) von 190 µSv innerhalb des 2‑monatigen Untersuchungszeitraumes ermittelt werden und lag damit bei einer kumuliert geschätzten Dosis über ein Jahr von ca. 1,2 mSv deutlich unter dem gesetzlichen Grenzwert von 20 mSv/a. Bei Einhaltung der gängigen Strahlenschutzmaßnahmen im Rahmen operativer Eingriffe in der Orthopädie und Unfallchirurgie ist in der Regel nicht mit einer Überschreitung des gesetzlichen Grenzwerts von 20 mSv/Jahr zu rechnen.

Objective Differentiation of an adrenal from an ovarian source of hyperandrogenemia can be challenging. Recent studies have highlighted the importance of 11-oxygenated C19 steroids to the androgen pool in humans. The aim of this study was to confirm the origin of 11-oxygenated androgens in females and to explore their potential use in the diagnostics of hyperandrogenic disorders. Methods We measured testosterone and its precursors (dehydroepiandrosterone-sulfate and androstenedione) and 11-oxygenated androgens (11β-hydroxyandrostenedione (11-OHA4) and 11-ketotestosterone (11-KT)) in the periphery, adrenal and ovarian veins in four different cases of hyperandrogenism in females (polycystic ovary syndrome (PCOS), primary bilateral macronodular adrenal hyperplasia, Sertoli–Leydig cell tumor and ovarian steroid cell tumor). Results Two patients demonstrate excessive testosterone secretion in neoplastic ovarian tumors which was not paralleled by a significant secretion of 11-oxygenated androgens as determined by adrenal and ovarian vein sampling. In androgen-secreting bilateral adrenal macronodular hyperplasia, steroid profiles were characterized by elevated 11-KT and 11-OHA4 concentrations in adrenal veins and the periphery. In the patient with PCOS, peripheral 11-KT concentrations were slightly elevated in comparison to the other patients, but the 11-KT and 11-OHA4 concentrations were comparable in ovarian veins and in the periphery. Conclusion This study confirms that 11-OHA4 and 11-KT are not biosynthesized by the ovary. We propose that the testosterone/11-KT ratio as well as 11-OHA4 could help identify predominant adrenal androgen excess and distinguish neoplastic and non-neoplastic ovarian androgen source. Significance statement This study confirms that 11β-hydroxyandrostenedione (11-OHA4) and 11-ketotestosterone (11-KT) are not biosynthesized by the human ovary. We propose that the testosterone/11-KT ratio as well as 11-OHA4 could help to identify predominant adrenal androgen excess and distinguish neoplastic and non-neoplastic ovarian androgen source.

Objective: To identify computed tomography (CT) findings of purulent infections in ancient Egyptian child mummies. Materials: Whole-body CT examination of 21 ancient Egyptian child mummies from German (n = 18), Italian (n = 1), and Swiss museums (n = 2). Methods: CT examinations were evaluated for estimation of age at death and sex of the children. CT examinations were systematically assessed for any CT findings of purulent infection. Results: The estimated age at death of the children ranged from about one year to the age of 12-14 years (mean 4.8 years). Twelve children were assessed as male, seven as female and in two sex was indeterminate. Three out of 21 child mummies (14.3%) had radiological evidence of purulent infections. In one mummy, a bandage-like structure at the right lower leg was detected that most likely represented a dressing of a skin lesion. Conclusions: This study appears to be the first to describe radiologically visualized structures consistent with dried pus in ancient Egyptian mummies. This study also appears to be the first to physically demonstrate an original ancient Egyptian dressing. Significance: These cases may serve as models for further paleopathological investigation. The evidence of an original dressing contributes to our knowledge of ancient Egyptian medicine. Limitations: CT was used as the only examination method as sampling of the wrapped mummies was not possible. Suggestions for further research: Radiological-pathological correlation in mummies in which physical sampling is available may reveal further insights into purulent infections in ancient Egypt.

AbstractSecondary sclerosing cholangitis (SSC) is a severe complication of intensive care treatment in critically ill patients. It is characterized by rapid onset and severe chlolestasis with elevation of gGT. In contrast to primary sclerosing cholangitis, SSC-CIP has a distinct and timely well defined trigger and can have a rapid progress to cirrhosis and liver failure. In context of the COVID-19-pandemic, there are reports about patients, who developed SSC after a severe COVID-infection and intensive care treatment.We report on a 62-year old patient without any relevant pre-existing illnesses, who suffered from severe COVID-19 pneumonia with the need for long term ventilation. In the course of the disease he developed a critical-illness-polyneuropathy a pronounced cholestasis. After recovery from COVID-pneumonia, the PNP regressed but the cholestasis progressed. MRCP showed only irregular intrahepatic bile ducts, while EUS showed echogenic intraductal longitudinal structures characteristic for intraductal casts and for SSC-CIP. This was confirmed with ERC, where the complete necrotic bile ducts could be extracted and retrieved for histological and molecular analysis.The patient was included in a scheduled ERC-program to prevent a progress of SSC and the concomitant cirrhosis.SSC is an often missed diagnosis, which obviously can also occur in COVID-patients. In case of elevated liver function tests with cholestasis, EUS might be the key diagnostic method to characterize intraductal casts and identify those patients who should undergo ERC.

In recent phantom studies low-contrast detectability was shown to be independent from variations in tube voltage in digital radiography (DR) systems. To investigate the transferability to a clinical setting, the lower extremities of human cadavers were exposed at constant detector doses with different tube voltages in a certain range, as proposed in the phantom studies. Three radiologists independently graded different aspects of image quality (IQ) in a comparative analysis. The grades show no correlation between IQ and kV, which means that the readers were not able to recognize a significant IQ difference at different kV. Signal-to-noise and contrast-to-noise ratios showed no significant differences in IQ despite the kV-setting variations. These findings were observed from a limited kV range setting. Higher kV-settings resulted in lowest patient exposure at constant IQ. These results confirm the potential of DR-systems to contribute to standardization of examination protocols comparable to computed tomography. This may prevent the trend to overexpose. Further investigations in other body regions and other DR-systems are encouraged to determine transferability.

CONTEXT:Recent studies support a bidirectional interaction between aldosterone and parathyroid hormone (PTH), possibly increasing the individual cardiovascular risk. Primary aldosteronism (PA) and primary hyperparathyroidism can occur simultaneously.OBJECTIVE:Our aim was to investigate the prevalence of hyperparathyroidism in PA.PATIENTS:We performed a case finding of primary hyperparathyroidism in a retrospective series of 503 patients with PA (cohort 1). We analysed primary and secondary hyperparathyroidism in 141 prospective PA patients who underwent PTH, serum calcium and phosphate measurements at time of diagnosis of PA (cohort 2).RESULTS:The prevalence for primary hyperparathyroidism was 1.2% in cohort 1, and 2.1% in cohort 2. Secondary hyperparathyroidism was found in 54.6% of the patients. Patients with secondary hyperparathyroidism had significantly higher aldosterone and lower potassium levels and took more antihypertensive medications compared to those with normal PTH levels. In multivariate analysis, aldosterone and 25-hydroxyvitamin D levels were significantly correlated with serum PTH levels. There was a nonsignificant trend to a higher cardiovascular morbidity in patients with secondary hyperparathyroidism. Patients with aldosterone producing adenoma had significantly higher PTH levels compared to patients with bilateral adrenal hyperplasia. After treatment, there was a significant decrease of PTH levels in both groups.CONCLUSION:Patients with PA frequently have primary or secondary hyperparathyroidism, which is alleviated by correction of PA by surgical or medical means. Patients affected by secondary hyperparathyroidism seem to have a more severe phenotype of PA and have a trend towards more cardiovascular co-morbidities.

CONTEXT:High dietary salt intake is known to aggravate arterial hypertension. This effect could be of particular relevance in the setting of primary aldosteronism (PA), which is associated with cardiovascular damage independent of blood pressure levels. The aim of this study was to determine the impact of therapy on salt intake in PA patients. PATIENTS AND METHODS:A total of 148 consecutive PA patients (66 with unilateral and 82 with bilateral PA) from the database of the German Conn's Registry were included. Salt intake was quantified by 24-hour urinary sodium excretion before and after initiation of PA treatment. STUDY DESIGN:Observational longitudinal cohort study. SETTING:Tertiary care hospital. RESULTS:At baseline, unilateral PA patients had a significantly higher urinary sodium excretion than patients with bilateral disease (205 vs 178 mmol/d, P = 0.047). Higher urinary sodium excretion correlated with an increased cardiovascular risk profile including proteinuria, impaired lipid, and glucose metabolism and was associated with higher daily doses of antihypertensive drugs to achieve blood pressure control. In unilateral disease, urinary sodium excretion dropped spontaneously to 176 mmol/d (P = 0.012) 1 year after unilateral adrenalectomy and remained low at 3 years of follow-up (174 mmol/d). In contrast, treatment with mineralocorticoid receptor antagonists (MRA) in bilateral PA patients was not associated with a significant change in urinary sodium excretion at follow-up (179 mmol/d vs 183 mmol/d). CONCLUSION:PA patients consuming a high-salt diet, estimated based on urinary sodium excretion, respond to adrenalectomy with a significant reduction of salt intake, in contrast to MRA treatment.

Background Clinical care of patients with cyclic Cushing’s syndrome (CS) is challenging. Classical pitfalls include incorrect subtyping, unnecessary surgical procedures and delayed definite treatment. Case presentation A 43-year-old female suffered from a rapidly cycling ectopic CS. She experienced six cycles of severe hypercortisolism within a 2 year period (maximum plasma cortisol 5316 nmol/L, normal range 124.2–662.4 nmol/L; maximum urinary free cortisol 79,469 nmol/24 h, normal range < 414 nmol/24 h) lasting 2–9 weeks. The episodes were associated with pronounced hypokalemia (lowest K + value recorded 2.4 mmol/l) and progressive signs and symptoms of CS. A bilateral inferior petrosal sinus sampling (BIPSS) performed during a trough phase was false positive for pituitary ACTH overproduction resulting in unnecessary transsphenoidal surgery while a second BIPSS performed during an active phase was indicative for ectopic CS. The 18 F-DOPA PET/CT showed a pancreatic lesion, which was subsequently partially removed. Surprisingly, the histopathology was conclusive for ACTH-positive lymph node metastasis located in the retro-duodenal tissue of an occult neuroendocrine tumor WHO grade II. The primary tumor has not been identified so far and, because of the persistent hypercortisolism, the patient underwent bilateral adrenalectomy. Two years later, ACTH levels started to increase progressively. Percutaneous biopsy of a newly identified suspected lesion in the fifth thoracic vertebra revealed a metastasis with positive staining for ACTH, synaptophysin and chromogranin A. Therapy with carboplatin and etoposide was started and, since then, the patient underwent 12 cycles of chemotherapy. Conclusions We report the challenging case of a rapidly cycling CS secondary to ACTH-secreting neuroendocrine intestinal tumor of unknown primary. We highlight the importance of performing diagnostic tests only during the phases of active cortisol secretion and as soon as first symptoms appear to avoid pitfalls.

PURPOSE:To assess the diagnostic value of intima media thickness measurements and contrast-enhanced ultrasound (CEUS) of the supraaortic arteries in the assessment of disease activity in Takayasu arteritis (TA). MATERIALS AND METHODS:Patients with TA and involvement of the carotid and/or subclavian/axillary arteries underwent CEUS imaging in addition to B-mode and color duplex ultrasound. The maximum IMT (mIMT) was measured and high-resolution CEUS of the most prominently thickened vessel segment was performed. Two blinded readers reviewed the CEUS movies, with semiquantitative assessment of microbubble enhancement of the arterial wall (grade 0: no or minimal; grade 1: moderate; grade 2: pronounced). Clinical symptoms, acute phase reactants, and established indices of clinical disease activity (NIH criteria, ITAS score) were recorded. RESULTS:40 examinations in 17 patients were analyzed. According to clinical judgement, 27 and 13 cases were classified as clinically inactive and active, respectively. An mIMT-cutoff of > 2.7 mm identified active disease with a sensitivity and specificity of 69.2 % and 88.9 %, respectively (area under the curve 0.83). The interobserver agreement of CEUS analysis was substantial (Cohen's kappa 0.76). By consensus reading, 17, 15, and 8 cases were classified as uptake grade 0, grade 1 and grade 2, respectively. Grade 0 uptake was exclusively present in 17 clinically inactive patients. Grade 1 uptake was seen in 10 patients with clinically inactive disease and 5 patients with clinically active disease. Grade 2 uptake was exclusively present in 8 patients with active disease. CONCLUSION:Both sonographic IMT measurements and high-resolution CEUS are promising in the ad-hoc assessment of disease activity in patients with TA.

BACKGROUND & AIMS: We studied the effects of diameter of covered, self-expandable, nitinol stents on survival times of patients with a transjugular intrahepatic portosystemic shunt (TIPS). METHODS: We collected data from 185 patients (median age, 55 y; 30% female) who received a covered nitinol stent, from February 2006 through September 2010, using the online multicenter German TIPS registry. TIPS were given to 107 patients for refractory ascites and to 78 patients for variceal bleeding. Patients at risk of hepatic encephalopathy (owing to advanced age, prior episodes) or liver failure (bilirubin level, >3 mg/dL), and bleeding patients receiving variceal embolization at TIPS, received 8-mm stents (n = 53). The remaining patients received 10-mm stents (n = 132). Eighty-one of the 10-mm stents were underdilated using 8-mm dilation balloons. Clinical and biochemical data were collected after TIPS placement at 1 month, 3 months, 6 months, 9 months, 1 year, and thereafter every 3 to 6 months. Groups were compared using propensity score analysis. RESULTS: Patients who received 8-mm stents survived significantly longer (34 +/- 26 mo) than patients who received 10-mm stents (18 +/- 19 mo), regardless of whether they were fully dilated or underdilated. When we compared 10-mm stents with or without underdilation, we found that a significantly higher proportion of patients who received underdilated stents survived for 1 month after TIPS placement (95% vs 84%; P = .03), but not for 3 months (P = .10). In multivariate analysis, 1-year mortality correlated with full dilation of the stent to 10 mm (hazard ratio [HR], 2.0; 95% CI, 1.1-3.5) and with serum creatinine concentration at baseline (HR, 1.5; 95% CI, 1.0-1.7). Five-year mortality was associated with use of the 10-mm stents (HR, 1.8; 95% CI, 1.4-2.7) and baseline concentration of creatinine (HR, 1.3; 95% CI, 1.1-1.6). CONCLUSIONS: A smaller stent (nominal diameter of 8 mm, but not underdilation of a 10-mm stent) is associated with a prolonged survival compared with 10-mm stents, independent of liver-specific prognostic criteria.

Die Mehrzahl der Patienten mit Leberzirrhose entwickelt als Folge der portalen Hypertension entweder Varizen oder Aszites. Die Frage, was diese beiden Patientengruppen unterscheidet, ist bis heute ungeklärt. Aus pathophysiologischer Sicht entsteht Aszites durch ein Ungleichgewicht von hepatischer Filtration und Lymphdrainage. Hierbei wird die Filtration durch den hydrostatischen und onkotischen Druck in den Sinusoiden reguliert, welche die sog. Starling forces darstellen. Wie u.a. durch die TIPS-Therapie gezeigt wird, führt die Abnahme des hydrostatischen Druckes zur Aszitesresorption und dessen erneute Zunahme (z.B. bei TIPS-Insuffizienz) zum erneuten Auftreten von Aszites. Die Bedeutung des onkotischen Druckes hingegen ist unzureichend erforscht und ist deshalb Gegenstand dieser Studie.

Objective Adrenal vein sampling (AVS) represents the current diagnostic standard for subtype differentiation in primary aldosteronism (PA). However, AVS has its drawbacks. It is invasive, expensive, requires an experienced interventional radiologist and comes with radiation exposure. However, exact radiation exposure of patients undergoing AVS has never been examined. Design and methods We retrospectively analyzed radiation exposure of 656 AVS performed between 1999 and 2017 at four university hospitals. The primary outcomes were dose area product (DAP) and fluoroscopy time (FT). Consecutively the effective dose (ED) was approximately calculated. Results Median DAP was found to be 32.5 Gy*cm2 (0.3–3181) and FT 18 min (0.3–184). The calculated ED was 6.4 mSv (0.1–636). Remarkably, values between participating centers highly varied: Median DAP ranged from 16 to 147 Gy*cm2, FT from 16 to 27 min, and ED from 3.2 to 29 mSv. As main reason for this variation, differences regarding AVS protocols between centers could be identified, such as number of sampling locations, frames per second and the use of digital subtraction angiographies. Conclusion This first systematic assessment of radiation exposure in AVS not only shows fairly high values for patients, but also states notable differences among the centers. Thus, we not only recommend taking into account the risk of radiation exposure, when referring patients to undergo AVS, but also to establish improved standard operating procedures to prevent unnecessary radiation exposure.

Purpose. Pre-clinical determination of reasonable simplified examination protocols before clinical application to assess the performance of a direct digital radiography (DDR) system. Material and methods. The experimental setup consists of a DDR system with fixed flat-panel detector (CsI). A phantom with low-contrast structures (LCS) was examined in two settings in order to simulate standard radiographs: (1) small peripheral joints like the wrist (no patient phantom, no anti-scatter grid) and (2) big proximal joints like the hip (20 cm water tank patient simulation and with an anti-scatter grid). Setup (1) was manually exposed at 55 kV/2 mAs, 60 k V/1.6 mAs and 65 k V/1.25 mAs. Setup (2) was automatically exposed at 1.6, 2.5, 4 and 6 mu Gy per kV-setting (80 +/- 5 kV). Contrast-detail curves (CDC) were generated by analyzer software. Results. Exposures of setup(1) showed similar CDC(p = 0.99) with a decreasing curve with larger diameter of LCS. In all exposures of setup (2) CDC were similar for all kV-settings (p > 0.93) with a decreasing curve with larger LCS diameter. CDC insignificantly decrease with increasing exposure dose (p > 0.38). Conclusion. Low-contrast detectability was independent of kV and marginally dependent on the dose, both within a certain range. This could be used to further reduce radiation dose and simplify examination protocols to be tested in a further clinical study.

Takayasu arteritis (TA) is a rare large vessel vasculitis, affecting the aorta and its major branches, typically in young women. In this case report, we present three cases of young women of Caucasian descent who experienced relapses while under treatment with the monoclonal humanized antibody to the interleukin 6 receptor, tocilizumab. Active vasculitic lesions of the supraaortic (common carotid and axillary) arteries were detected and characterized via high resolution contrast enhanced ultrasound. Based on these cases, we discuss the potential role of contrast enhanced ultrasound in the diagnosis and follow-up of TA as well as the current data on the efficacy of tocilizumab in the treatment of TA.

Context: Primary aldosteronism (PA) represents the most frequent form of endocrine hypertension. Hyperaldosteronism and hypercortisolism both induce excessive left ventricular hypertrophy (LVH) compared with matched essential hypertensives. In recent studies frequent cosecretion of cortisol and aldosterone has been reported in patients with PA. Objective: Our aim was to investigate the impact of cortisol cosecretion on LVH in patients with PA. We determined 24-hour excretion of mineralocorticoids and glucocorticoids by gas chromatography-mass spectrometry and assessed cardiac remodeling using echocardiography initially and 1 year after initiation of treatment of PA. Patients: We included 73 patients from the Munich center of the German Conn's registry: 45 with unilateral aldosterone-producing adenoma and 28 with bilateral adrenal hyperplasia. Results: At the time of diagnosis, 85% of patients with PA showed LVH according to left ventricular mass index [(LVMI); median 62.4 g/m(2.7)]. LVMI correlated positively with total glucocorticoid excretion (r(2) = 0.076, P = 0.018) as well as with tetrahydroaldosterone excretion (r(2) = 0.070, P = 0.024). Adrenalectomy led to significantly reduced LVMI in aldosterone-producing adenoma (P < 0.001) whereas mineralocorticoid receptor antagonist therapy in bilateral adrenal patients with hyperplasia reduced LVMI to a lesser degree (P = 0.024). In multivariate analysis, the decrease in LVMI was positively correlated with total glucocorticoid excretion and systolic 24-hour blood pressure, but not with tetrahydroaldosterone excretion. Conclusion: Cortisol excess appears to have an additional impact on cardiac remodeling in patients with PA. Treatment of PA by either adrenalectomy or mineralocorticoid receptor antagonist improves LVMI. This effect was most pronounced in patients with high total glucocorticoid excretion.

AIM:To determine the diagnostic yield of 18 F-fluorodeoxyglucose positron emission tomography (PET) in disease activity assessment of large vessel vasculitides (LVV).METHODS:Patients with LVV who had undergone PET (between 2004 and June 2010) or PET co-registered with computed tomography (PET/CT; since June 2010) were identified. Clinical disease activity was assessed using established scoring systems. PET images were reviewed by two blinded nuclear medicine physicians. Uptake of the aortic wall was compared to the liver uptake utilizing a visual 4-point score, with a vessel wall uptake similar or higher than liver uptake considered as active disease. Various target-to-background ratios were calculated. Receiver operator characteristics analysis was applied to determine the diagnostic accuracy of PET for detecting clinically active disease. Interobserver agreement of visual readings was measured with Cohen´s kappa.RESULTS:Eighty examinations in 62 patients were analyzed, with a mean time between diagnosis and PET of 106 ± 171 weeks. Fifty-seven cases were finally classified as clinically active and 23 cases as clinically inactive. With a cut-off value of 1.3, the aorta-to-liver ratio yielded a sensitivity and specificity of 84.2% and 82.6% (area under the curve 0.9). Overall, sensitivity and specificity of visual analysis were 68.4% and 91.3%, but sensitivity decreased to 54% in patients treated for more than 3 months. Interobserver agreement of visual rating was excellent (κ: 0.93).CONCLUSION:Positron emission tomography is specific and reliable in disease activity assessment of LVV, but lacks sensitivity for detecting active disease in patients under long-term immunosuppressive treatment.