Whole-body SPECT/CT for bone scintigraphy: diagnostic value and effect on patient management in oncological patients.

PURPOSE: This study was designed to assess the additional value of SPECT/CT of the trunk used in conjunction with conventional nuclear imaging and its effects on patient management in a large patient series. METHODS: In 353 patients, whole-body scintigraphy (WBS), SPECT, and SPECT/CT were prospectively performed for staging and restaging. SPECT/CT of the trunk was performed in all patients. In the 308 evaluable patients (211 with breast cancer, 97 with prostate cancer), clinical follow-up was used as the gold standard. Bone metastases were confirmed in 72 patients and excluded in 236. Multistep analyses per lesion and per patient were performed. Clinical relevance was expressed in terms of downstaging and upstaging rates on a per-patient basis. RESULTS: In the total patient group, sensitivities, specificities, and negative and positive predictive values on a per-patient basis were 93 %, 78 %, 95 % and 59 % for WBS, 94 %, 71 %, 97 % and 53 % for SPECT, and 97 %, 94 %, 97 % and 88 % for SPECT/CT, respectively. In all subgroups, specificity and positive predictive value were significantly (p<0.01) better with SPECT/CT. Downstaging of metastatic disease in the total, breast cancer and prostate cancer groups using SPECT/CT was possible in 32.1 %, 33.8 % and 29.5 % of patients, respectively. Upstaging in previously negative patients by additional SPECT/CT was observed in three breast cancer patients (2.1 %). Further diagnostic imaging procedures for unclear scintigraphic findings were necessary in only 2.5 % of patients. SPECT/CT improved diagnostic accuracy for defining the extent of multifocal metastatic disease in 34.6 % of these patients. CONCLUSIONS: SPECT/CT significantly improved the specificity and positive predictive value of bone scintigraphy in cancer patients. In breast cancer patients, we found a slight increase in sensitivity. SPECT/CT had a significant effect on clinical management because of correct downstaging and upstaging, better definition of the extent of metastases, and a reduction in further diagnostic procedures.

Beta-trace protein-based equations for calculation of GFR in renal transplant recipients.

Recently, we showed that serum beta-trace protein (BTP) is an alternative marker of glomerular filtration rate (GFR) in renal transplant recipients (RTR). We have now developed three BTP-based GFR formulae derived by multiple regression analyses from the patients who had participated in that study. Currently, we validated the diagnostic performance of these BTP-formulae in 102 consecutive RTR who underwent a technetium diethylenetriamine pentaacetic acid (DTPA) clearance for GFR measurement in comparison to the re-expressed Modification of Diet in Renal Disease (MDRD) equation and a recently proposed BTP-based equation (referred to as 'White equation'). The best-performing BTP formula was found to be: GFR = 89.85 x BTP(-0.5541)x urea(-0.3018). This equation estimated true GFR virtually without bias (+0.43 mL/min/1.73 m(2), not significant [NS]), while a small, but significant, overestimation was seen for the MDRD formula (+3.43 mL/min/1.73 m(2), p = 0.003). Precision and accuracies within 50% of true GFR (93.1% and 88.2%, respectively) tended to be higher for the BTP formula, but the differences did not reach significance. The White equation overestimated the true GFR by 9.43 mL/min/1.73 m(2)(p = 0.001), and was inferior with respect to precision and 50% accuracy (79.4%). BTP-based GFR calculations are reliable, and may serve as an alternative to the re-expressed MDRD equation.

Renal anemia aggravated by long-term parvovirus B19 and cytomegalovirus infection in a renal transplant patient: case report and evaluation of B19 seroprevalence in dialysis patients.

Due to viral replication in erythroid precursor cells, severe anemia represents a major complication of B19 infection. However, cytomegalovirus (CMV) is the leading cause of virus-induced complications with a significant impact on graft outcome of renal transplant patients. Herein, we present a long-term B19 infection in a 45-year-old female renal transplant patient, which aggravated the renal anemia associated with a concomitant CMV infection. Since no data were available on the seroprevalence of this virus in pretransplant patients, we determined the B19 serostatus of 90 dialyzed pretransplant adult subjects.

The fibrinolytic system in chronic renal failure.

BACKGROUND: Patients with chronic renal failure (CRF) face a high risk of cardiovascular morbidity and mortality. Impaired fibrinolysis has recently been acknowledged to function as a risk factor for cardiovascular ischemic complications. Whether changes in fibrinolytic function contribute to the increased cardiovascular risk in CRF, however, remains unclear. METHODS: In the present study, tissue-plasminogen activator (t-PA) and its main antagonist plasminogen activator inhibitor-1 (PAI- 1) were determined in 12 subjects with normal renal function (group A) [serum creatinine (Cr) <1.3 mg/dl], 24 patients with impaired renal function (Cr 1.3-6.5 mg/dl) (group B) and 22 patients with endstage renal disease (ESRD) on hemodialysis (Cr>6.5 mg/dl) (group C). RESULTS: Plasma concentrations of PAI-1 and t-PA antigen as well as the PAI-1:t-PA molar ratio were unchanged in group B as compared to group A. However, in ESRD patients (group C), t-PA concentrations markedly decreased [13.7 +/- 2.9 ng/ml vs. 32.8 +/- 4.7 ng/ml (group B, p <0.01) and 35.4 +/- 8.4 ng/ml (group A, p <0.01)] while PAI-1 antigen concentrations remained in the control range. Thus, the PAI-1:t-PA molar ratio significantly increased in group C patients [12.4 +/- 4. 0 vs. 6.0 +/- 2.5 (group B; p<0.01) and 4.5 +/- 1.7 (group A; p<0.01]. CONCLUSIONS: From our data it may be suggested that fibrinolysis is markedly disturbed in ESRD due to a decreased availability of t-PA. Thus, it may be speculated that the development of atherothrombotic events in hemodialysis patients is, at least in part, due to an impaired fibrinolysis.

Calculation of glomerular filtration rate based on cystatin C in cirrhotic patients.

BACKGROUND: Plasma creatinine and creatinine clearance are of limited value for the estimation of renal function in cirrhotics. In these patients, cystatin C (Cys C) has been proposed as an alternative marker of glomerular filtration rate (GFR) and Cys C-based equations for calculation of GFR have been developed in non-cirrhotic patient cohorts. METHODS: We retrospectively analyzed correlation, bias, precision and accuracy of two Cys C-based formulae (Larsson and Hoek) for GFR estimation in comparison with two creatinine-based equations (Cockroft & Gault and MDRD). The Cys C was determined by an immunonephelometric method. The GFR was measured by means of inulin clearance in 44 consecutive patients with liver cirrhosis. RESULTS: On average, inulin clearance was 28.3 (95% CI: 29.2-41.3 ml/min/1.73 m2). Creatinine as well as Cys C-based equations overestimated the true GFR by 105-154%. However, Cys C-based equations showed significantly lower bias and higher precision than the creatinine-based formulae. Correlation and accuracy tended to be better with the Hoek and Larsson equation than with the Cockroft & Gault or MDRD formulae. Hoek and Larsson equations showed a similar diagnostic performance in all statistical procedures. CONCLUSION: Our data suggest a significant improvement of GFR estimation in liver cirrhotics by means of the Cys C-based Hoek and Larsson formulae. However, all estimates remain a crude approximation of true GFR and thus cannot replace gold standard methods.

Cystatin C-based calculation of glomerular filtration rate in kidney transplant recipients.

Cystatin C (Cys C) has been shown to be an alternative marker of renal function. However, estimation of the glomerular filtration rate (GFR) based on Cys C has received little attention. Recently, several Cys C-based equations were developed in different patient cohorts. To date, the benefit of a Cys C-based GFR calculation in patients after renal transplantation (RTx) remains to be elucidated. We compared the diagnostic accuracy of three Cys C-based formulae (Larsson, Hoek, Filler which used an immunonephelometric method) with the results of the Modification of Diet in Renal Disease (MDRD) formula. GFR was measured by means of technetium-diethylenetriamine pentaacetic acid ((99m)Tc-DTPA) clearance in 108 consecutive patients after RTx. Correlation coefficients of all calculated GFR estimates with the true GFR were high but did not differ significantly from one another (0.83-0.87). The MDRD and Filler equations overestimated GFR significantly, whereas the Larsson equation significantly underestimated GFR. Bias of the Hoek formula was negligible. Precision of the Hoek (8.9 ml/min/1.73 m(2)) and Larsson equations (9.6 ml/min/1.73 m(2)) were significantly better than MDRD equations (11.4 ml/min/1.73 m(2); P< or =0.035 each). Accuracy within 30% of real GFR was 67.0 and 65.1% for the MDRD and Filler formulae, and 77.1% for the Larsson and Hoek formulae, respectively. Accuracy within 50% of true GFR for the Hoek formula (97.2%) was better than for the MDRD equations (85.3%). Cys C-based formulae may provide a better diagnostic performance than creatinine-based equations in GFR calculation after RTx.

Cystatin C as an endogenous marker of glomerular filtration rate in renal transplant patients.

BACKGROUND: Serum creatinine is the most common endogenous marker used to estimate the glomerular filtration rate (GFR). However, creatinine depends considerably on muscle mass, and its tubular secretion increases, especially in chronic renal failure. Cystatin C is a 13-kD protease inhibitor which is produced by all nucleated cells and is independent of muscle mass and sex. Cystatin C is eliminated by glomerular filtration and metabolized by proximal tubular cells. Its measurement has been proposed as an alternative and more sensitive marker of GFR than creatinine in patients with slight to moderately decreased GFR. METHODS: We investigated serum cystatin C levels in comparison with creatinine as a single measurement for estimation of GFR in 173 patients after renal transplantation. GFR was calculated as creatinine clearance according to standard equations. RESULTS: Serum creatinine correlated well with cystatin C (r = 0.84; p < 0.0001). No significant differences were obtained for the comparison of the linear correlation of 1/creatinine with creatinine clearance (r = 0.77; p < 0.0001) and for the linear correlation of 1/cystatin C with creatinine clearance (r = 0.73; p < 0.0001). However, we found a significant advantage of cystatin C in detecting a clinical relevant reduction of kidney function (GFR <70 ml/min; p = 0.0047, McNemar test). CONCLUSION: Cystatin C is an alternative marker for the assessment of GFR in renal allograft recipients that may be superior to creatinine.