Generation of potentially inhibitory autoantibodies to ADAMTS13 in coronavirus disease 2019

It has recently been shown that von Willebrand factor (VWF) multimers contribute to immunothrombosis in Coronavirus disease 2019 (COVID-19). Since COVID-19 is associated with an increased risk of autoreactivity, the present study investigates, whether the generation of autoantibodies to ADAMTS13 contributes to this finding. In this observational prospective controlled multicenter study blood samples and clinical data of patients hospitalized for COVID-19 were collected from April to November 2020. The study included 156 individuals with 90 patients having confirmed COVID-19 of mild to critical severity. 30 healthy individuals and 36 critically ill ICU patients without COVID-19 served as controls. ADAMTS13 antibodies occurred in 31 (34.4%) COVID-19 patients. Antibodies occurred more often in critically ill COVID-19 patients (55.9%) than non-COVID-19 ICU patients and healthy controls (5.6% and 6.7%; p < 0.001), respectively. Generation of ADAMTS13 antibodies in COVID-19 was associated with lower ADAMTS13 activity (56.5%, interquartile range (IQR) 21.25 vs. 71.5%, IQR 24.25, p = 0.0041), increased disease severity (severe or critical in 90% vs. 62.3%, p = 0.019), and a trend to higher mortality (35.5% vs. 18.6%, p = 0.077). Median time to antibody development was 11 days after first positive SARS-CoV-2-PCR specimen. Gel analysis of VWF multimers resembled the constellation in patients with TTP. The present study demonstrates for the first time, that generation of ADAMTS13 antibodies is frequent in COVID-19, associated with lower ADAMTS13 activity and increased risk of an adverse disease course. These findings provide a rationale to include ADAMTS13 antibodies in the diagnostic workup of SARS-CoV-2 infections.

In vitro and in vivo evidence that the switch from calcineurin to mTOR inhibitors may be a strategy for immunosuppression in Epstein-Barr virus-associated post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder is a life-threatening complication of immunosuppression following transplantation mediated by failure of T cells to control Epstein-Barr virus (EBV)-infected and transformed B cells. Typically, a modification or reduction of immunosuppression is recommended, but insufficiently defined thus far. In order to help delineate this, we characterized EBV-antigen-specific T cells and lymphoblastoid cell lines from healthy donors and in patients with a kidney transplant in the absence or presence of the standard immunosuppressants tacrolimus, cyclosporin A, prednisolone, rapamycin, and mycophenolic acid. Phenotypes of lymphoblastoid cell-lines and T cells, T cell-receptor-repertoire diversity, and T-cell reactivity upon co-culture with autologous lymphoblastoid cell lines were analyzed. Rapamycin and mycophenolic acid inhibited lymphoblastoid cell-line proliferation. T cells treated with prednisolone and rapamycin showed nearly normal cytokine production. Proliferation and the viability of T cells were decreased by mycophenolic acid, while tacrolimus and cyclosporin A were strong suppressors of T-cell function including their killing activity. Overall, our study provides a basis for the clinical decision for the modification and reduction of immunosuppression and adds information to the complex balance of maintaining anti-viral immunity while preventing acute rejection. Thus, an immunosuppressive regime based on mTOR inhibition and reduced or withdrawn calcineurin inhibitors could be a promising strategy for patients with increased risk of or manifested EBV-associated post-transplant lymphoproliferative disorder.

Effect of Nephrectomy After Allograft Failure on Inflammation, Erythropoiesis, Donor-Specific Antibodies, and Outcome of Re-Transplantation

Background

Morbidity and mortality rates are high for patients returning to dialysis after renal graft failure. Keeping failed kidney transplants in situ with concomitant minimization or withdrawal of immunosuppression is standard of care in many transplant centers. It is unclear, however, whether the resulting allospecific immune response can cause a microinflammatory milieu. The present work investigated the impact of allograft nephrectomy on systemic inflammation, erythropoiesis, and donor-specific antibodies (DSA).

Material/Methods

We performed a retrospective analysis evaluating C-reactive protein (CRP), hemoglobin concentration (Hb), ferritin, iron substitution dosages, erythropoietin dosages, and DSA in 92 transplant recipients with allograft failure, of whom 49 did not (Group A) and 43 did undergo transplant nephrectomy (Group B). Blood samples and clinical data were obtained 3–6 months after returning to dialysis. We additionally assessed outcome of kidney re-transplantation in a 10-year follow-up.

Results

There was no significant difference in Hb concentrations, ferritin concentrations, CRP concentrations, iron, and EPO substitution dosages between the 2 groups. Patients undergoing nephrectomy had a significantly higher prevalence of DSA (65.1% vs 38.8%, P<0.0001). In the 10-year follow-up, 3 patients (12%) of Group B and none in Group A had allograft failure after primary successful re-transplantation.

Conclusions

Keeping a kidney graft in situ after returning to dialysis did not lead to an increase in microinflammation. Although DSA develops in more than 50% of patients after an allograft nephrectomy, the outcome of a renal re-transplantation seems to be unaffected. Thus, both strategies are feasible options in kidney transplant recipients after return to dialysis.

MO149: Effect of Plasma Exchange on COVID-19 Associated Excess of Von Willebrand Factor and Inflammation in Critically Ill Patients

BACKGROUND AND AIMS

Ubiquitous microthromboses in the pulmonary vasculature play a crucial role in the pathogenesis of COVID-19 associated acute respiratory distress syndrome (ARDS). Excess of von Willebrand factor (vWf) with intravascular multimer formation was identified as a key driver of this finding. Plasma exchange (PLEX) might be a therapeutic option to restore the disbalance between vWf and ADAMTS13. We report the effects of PLEX on vWf, ADAMTS13, inflammatory cytokines and parameters of ventilation.

METHOD

We investigated 25 patients, who were on mechanical ventilation for COVID-19 pneumonia with ARDS at two German university hospitals. All patients received PLEX as an ultima ratio measure for refractory ARDS. VWf antigen (vWf: Ag), ADAMTS13 activity, a cytokine panel mirroring the inflammatory situation and clinical parameters were assessed before and after three to six PLEX therapies with fresh frozen plasma.

RESULTS

Before the PLEX sequence, there was an excessive release of vWf: Ag (425.4 ± 167.5%) and mildly reduced ADAMTS13 activity (49.7 ± 23.3%). After the PLEX series, there was a significant increase of ADAMTS13 activity to 62.4 ± 17.7% (P = .029) and a significant decrease of vWf: Ag to 336.1 ± 138.2% (P = .041) resulting in a 63% improvement of the ADAMT13/vWf: Ag ratio from 14.5 ± 10.0 to 23.7 ± 14.6  (P = .024). Comparison of parameters before and after individual PLEX sessions (n = 35) revealed a mean reduction of vWf from 387.8 ± 165.1% to 213.2 ± 62.3% (P = .001) and an increase of ADAMTS13 activity from 60.4 ± 20.1% to 70.5 ± 14.0% (P = .001). Parallelly, monocyte chemotactic protein-1 and interleukin-18 decreased significantly (P = .034 each). Along the PLEX sequence lactate dehydrogenase (P = .001), C-reactive protein (P = .001), and positive end expiratory pressure (P = .01) significantly decreased accompanied by an improvement of Horovitz index (P = .001).

CONCLUSION

PLEX restores the disbalance between ADAMTS13 and vWf: Ag, a driver of immunothrombosis. Moreover, it reduces the inflammatory state and is associated with a benefit of ventilation parameters. These findings render a further rationale to regard PLEX as a therapeutic option in severe COVID-19.

Impact of weather changes on hospital admissions for hypertension

Blood pressure (BP) shows a seasonal variation with higher levels at lower temperatures. Many hypertensives, however, report on BP disturbances rather in association with acutely changing weather conditions than with absolute temperatures. To date, the impact of changing meteorological parameters on hypertensive episodes remains elusive. We performed a retrospective time series regression analysis on 203,703 patients in three hospitals in Germany between 2010 and 2018, of whom 7362 patients were admitted for hypertensive disease. Numbers of daily admissions for hypertension were associated with metereological data obtained from three nearby weather stations. Data comprised temperature (mean, maximal, minimal and range within 24 h), athmospheric pressure, and precipitation. Changes of these parameters were calculated over a two and three day period. There was an inverse correlation between maximal daily temperature and the number of admissions for hypertensive disease, which remained significant both after adjustment for seasonality and week day in a spline model and in a constrained distributed lag model. A decrease of maximal temperature by 5 °C was associated with a 3% increase of risk for admission for hypertension and vice versa. There were no significant effects of precipitation and athmospheric pressure on the number of admissions. With regard to all observed metereological parameters, neither the change within two, nor within three days was consistently associated with the number of daily admissions. High temperatures are associated with lower numbers of hypertensive episodes requiring hospital admission. In contrast to the subjective perception of many hypertensive patients, however, acutely changing weather conditions are not associated with a higher risk of hypertensive emergency.

Effect of plasma exchange on COVID-19 associated excess of von Willebrand factor and inflammation in critically ill patients

Ubiquitous microthromboses in the pulmonary vasculature play a crucial role in the pathogenesis of COVID-19 associated acute respiratory distress syndrome (ARDS). Excess of Willebrand factor (vWf) with intravascular multimer formation was identified as a key driver of this finding. Plasma exchange (PLEX) might be a therapeutic option to restore the disbalance between vWf and ADAMTS13. We report the effects of PLEX on vWf, ADAMTS13, inflammatory cytokines and parameters of ventilation. We investigated 25 patients, who were on mechanical ventilation for COVID-19 pneumonia with ARDS at two German university hospitals. All patients received PLEX as an ultima ratio measure for refractory ARDS. VWf antigen (vWf:Ag), ADAMTS13 activity, a cytokine panel mirroring the inflammatory situation and clinical parameters were assessed before and after three to six PLEX therapies with fresh frozen plasma. Before the PLEX sequence there was an excessive release of vWf:Ag (425.4 ± 167.5%) and mildly reduced ADAMTS13 activity (49.7 ± 23.3%). After the PLEX series, there was a significant increase of ADAMTS13 activity to 62.4 ± 17.7% (p = 0.029) and a significant decrease of vWf:Ag to 336.1 ± 138.2% (p = 0.041) resulting in a 63% improvement of the ADAMT13/vWf:Ag ratio from 14.5 ± 10.0 to 23.7 ± 14.6, p = 0.024. Comparison of parameters before and after individual PLEX sessions (n = 35) revealed a mean reduction of vWf from 387.8 ± 165.1 to 213.2 ± 62.3% (p = 0.001) and an increase of ADAMTS13 activity from 60.4 ± 20.1 to 70.5 ± 14.0% (p = 0.001). Parallelly, monocyte chemotactic protein-1 and interleukin-18 decreased significantly (p = 0.034 each). Along the PLEX sequence lactate dehydrogenase (p = 0.001), C-reactive protein (p = 0.001), and positive end expiratory pressure (p = 0.01) significantly decreased accompanied by an improvement of Horovitz index (p = 0.001). PLEX restores the disbalance between ADAMTS13 and vWf:Ag, a driver of immunothrombosis. Moreover, it reduces the inflammatory state and is associated with a benefit of ventilation parameters. These findings render a further rationale to regard PLEX as a therapeutic option in severe COVID-19.

Feasibility of non-invasive measurement of central blood pressure and arterial stiffness in shock

BACKGROUND

Patients in haemodynamic shock are in need for an intensive care treatment. Invasive haemodynamic monitoring is state of the art for these patients. However, evolved, non-invasive blood pressure monitoring devices offer advanced functions like the assessment of central blood pressure and arterial stiffness. We analysed the feasibility of two oscillometric blood pressure devices in patients with shock.

METHODS

We performed a monocentre prospective study, enrolling 57 patients admitted to the intensive care unit (ICU), due to septic and/or cardiogenic shock. We assessed invasive and non-invasive peripheral and central blood pressure <24 hours and 48 hours after admission on the ICU. Additional haemodynamic parameters such as pulse wave velocity (PWV), augmentation pressure and augmentation index were obtained through Mobil-o-Graph PWA (IEM) and SphygmoCor XCEL (AtCor Medical).

RESULTS

A complete haemodynamic assessment was successful in all patients (48) with the Mobil-o-Graph 24 hours PWA and in 29 patients with the SphygmoCor XCEL (P = .001), when cases of death or device malfunction were excluded. Reasons for failure were severe peripheral artery disease, haemodynamic instability, oedema and agitation. Invasive blood pressure showed a sufficient correlation with both devices; however, large differences between invasive and non-invasive techniques were recorded in Bland-Altmann analysis (P < .05 for all parameters). PWV differed between the two devices.

CONCLUSION

Non-invasive peripheral blood pressure measurement remains a rescue technique. However, non-invasive assessment of arterial stiffness and central blood pressure is possible in patients with septic or cardiogenic shock. Further studies are required to assess their clinical significance for patients in shock.

Impact of Histidine-Tryptophan-Ketoglutarate Versus University of Wisconsin Solution on the Outcome of Pancreas Transplant With Cold Ischemic Time ≥12 Hours: A Retrospective Study

OBJECTIVES

Histidine-tryptophan-ketoglutarate and University of Wisconsin solutions are currently used for pancreas graft preservation. Our hypothesis was whether the use of histidine-tryptophan-ketoglutarate solution is associated with worse pancreas graft survival than University of Wisconsin solution, in general and after prolonged cold ischemic time of ≥12 hours.

MATERIALS AND METHODS

This retrospective study investigated the impact of static cold storage in histidine-tryptophan-ketoglutarate (n = 133) versus University of Wisconsin (n = 107) solution on outcomes of 240 pancreas transplant procedures. Patient and graft survival rates were compared after 1, 3, and 5 years in both groups. Serum lipase, amylase, and C-reactive protein levels and incidence of surgical complications were evaluated at postoperative week 1. A subgroup analysis of 96 grafts (52 with histidine-tryptophanketoglutarate/44 with University of Wisconsin) with pancreas graft cold ischemic time ≥12 hours was also performed.

RESULTS

At mean follow-up of 75.2 ± 9.9 months, both groups demonstrated comparable short- and long-term patient survival. Overall, pancreas graft survival was slightly better in the histidine-tryptophan-ketoglutarate group (Kaplan-Meier analysis, log-rank P = .013). However, the subgroup analysis of grafts with cold ischemic time ≥12 hours showed slightly better pancreatic graft survival in the University of Wisconsin group, although not significantly (log-rank P = .95). Serum lipase and C-reactive protein levels at postoperative week 1 were higher in the histidinetryptophan-ketoglutarate group. Surgical complications were comparable. Multivariable Cox regression analysis identified neither solution as a risk factor affecting patient and graft survival.

CONCLUSIONS

Although a direct comparison between histidine-tryptophan-ketoglutarate and University of Wisconsin showed better pancreas graft survival with histidine-tryptophan-ketoglutarate, the multivariable analysis showed that the perfusion solution does not significantly influence patient and graft survival. However, in the analysis of transplants with cold ischemic time ≥12 hours, pancreas graft survival was slightly better in the University of Wisconsin group, although not significantly.

Biopsy findings after detection of de novo donor-specific antibodies in renal transplant recipients: a single center experience

Background

De novo donor-specific antibodies (DSA) are associated with an increased risk of antibody-mediated rejection and a substantial reduction of allograft survival. We hypothesized that detection of DSA should prompt a biopsy even in the absence of proteinuria and loss of estimated glomerular filtration rate (eGFR). However, data on a population without proteinuria or loss of kidney function is scant, and this is the main novelty of our study design.

Methods

Single center retrospective analysis on biopsy findings after detection of de novo DSA. One-hundred-thirty-two kidney and pancreas-kidney transplant recipients were included. Eighty-four of these patients (63.6%) underwent allograft biopsy. At the time of biopsy n = 50 (59.5%) had a protein/creatinine ratio (PCR) > 300 mg/g creatinine and/or a loss of eGFR ≥ 10 ml/min in the previous 12 months, whereas 40.5% did not. Diagnosis of rejection was performed according to Banff criteria.

Results

Seventy-seven (91.7%) of the biopsies had signs of rejection (47.6% antibody mediated rejection (ABMR), 13.1% cellular, 20.2% combined, 10.7% borderline). Among subjects without proteinuria or loss of eGFR ≥ 10 ml/min/a (n = 34), 29 patients (85.3%) showed signs of rejection (44.1% antibody mediated (ABMR), 14.7% cellular, 11.8% combined, 14.7% borderline).

Conclusion

The majority of subjects with de novo DSA have histological signs of rejection, even in the absence of proteinuria and deterioration of graft function. Thus, it appears reasonable to routinely perform an allograft biopsy after the detection of de novo DSA.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-01040-y.

Coronavirus Disease 2019 Associated Risk Score, Behavior, and Symptom Prevalence in German Transplant Recipients

Background

Transplant recipients are prone to developing severe infections because of immunosuppression. Therefore, studying the manifestation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in transplant recipients is of particular importance.

Methods

One hundred twelve transplant patients consecutively visiting the outpatient department of 2 German transplant centers were included in this study after providing written informed consent. The patients were interviewed about coronavirus disease 2019 (COVID-19) symptoms and history. Nasopharyngeal swabs were analyzed by SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR). SARS-CoV-2 IgG and IgA were measured concomitantly in patient sera by enzyme-linked immunosorbent assay.

Results

The risk of severe COVID-19 according to 2 recent scores differed among the analyzed patients. All patients were well educated about their presumed higher risk of a severe COVID-19 and described performing self-isolation wherever possible. Nevertheless, 20 patients reported contact with someone suspected of having COVID-19 or who tested positive shortly thereafter (18%). Despite this relatively high exposure, no clinically relevant case of COVID-19 was reported. Though SARS-CoV-2 IgG and IgA were found in 3 patients (3%); 2 patients were asymptomatic and only 1 had mild COVID-19 symptoms and positive RT-PCR 4 weeks earlier. There were no occult SARS-CoV-2 infections, as demonstrated by negative PCR tests.

Conclusion

Despite the high exposure level, the incidence of COVID-19 remained very low. Because of the differences in COVID-19 risk, balancing risk exposure and quality of life should be recommended.

Psychological Responses to the Coronavirus Disease 2019 Pandemic in Renal Transplant Recipients

BACKGROUND

Renal transplant recipients are at increased risk for an adverse course of coronavirus disease 2019 (COVID-19), most likely due to immunosuppression and the high level of cardiovascular comorbidity. Many transplant recipients are aware of these facts. The psychological effects of this knowledge, however, remain elusive.

METHODS

Cross-sectional study on 62 renal transplant recipients. Fifty cardiovascular outpatients without immunosuppression and 55 healthy subjects served as control. We performed a focused psychological assessment during the pandemic (April 2020) and compared the data with a time 6 months before. Additionally, an intergroup analysis was performed for the data during the pandemic. The analysis was performed by means of a questionnaire derived from KPD-38. We extracted 5 questions focusing on the parameters "life satisfaction" and perceived "action competence." Life satisfaction score ranged from 2 to 8, and the score for action competence from 5 to 20.

RESULTS

Both life satisfaction and perceived action competence were significantly lower during the pandemic than 6 months before in all the 3 groups (P < .005 each). During the pandemic median levels of life satisfaction did not significantly differ between the 3 groups (transplant recipients 6, interquartile range [IQR] 4-7; cardiovascular patients 5, IQR: 4-6; healthy controls 6, IQR 5-7; Kruskal-Wallis P > .05). In contrast, the perceived action competence was higher in healthy subjects (15, IQR 12-17) than in both renal transplant recipients (13, IQR 10-15) and cardiovascular patients (13, IQR 8-14, Kruskal-Wallis P = .0003).

CONCLUSION

The COVID-19 pandemic has negative effects on life satisfaction and perceived action competence in renal transplant recipients, cardiovascular patients without immunosuppression, and healthy subjects. The effects on life satisfaction in transplant recipients did not differ from nonimmunocompromised patients or healthy controls. In contrast, the feeling of reduced action competence exceeded healthy controls, most likely due to a subjective need for stricter social distancing to avoid infection.

Vaccination Against Urinary Tract Infection After Renal Transplantation

BACKGROUND

Recurrent urinary tract infections (UTIs) increase mortality and reduce graft survival after renal transplantation. Because current prophylactic strategies such as methionine, cranberry juice, and antibiotics fail to sufficiently prevent recurrent infections in a substantial number of patients, there is a clinical need for alternative approaches. The present work describes first experiences with an immunization strategy against bacterial strains after kidney transplantation.

METHODS

We performed a retrospective single-center analysis of an immunization approach against 10 strains of inactivated bacteria (StroVac). A total of 14 renal transplant recipients with 3 or more UTI episodes/year underwent immunization with 3 subcutaneous injections of inactivated bacteria (follow-up 12 months before to 12 months after immunization). These patients were compared to 14 renal transplant patients without immunization who were matched for number of UTIs and time after transplantation (24 months follow-up). We compared the UTI incidence and potential side effects, including development of de novo donor-specific antibodies (DSA).

RESULTS

The immunization significantly decreased the incidence of UTIs from 3.4 ± 1.3 to 0.9 ± 1.0 by 74.9%. The incidence did not change from year 1 to year 2 of the observation period in the control group. Immunization was tolerated well, without any clinical complaints. There were no de novo DSAs in the first year after immunization.

CONCLUSIONS

Immunization against inactivated bacterial strains substantially reduced the incidence of UTIs without eliciting any safety concerns in this small cohort of renal transplant recipients. This strategy may be a helpful expansion of our preventive measures in patients with recurrent UTIs.

Outcome of Kidney Transplantation Using Organs From Brain-dead Donors Older Than 75 Years

PURPOSE

We investigated whether older donor kidneys aged >75 years have acceptable long-term function and if recipients can benefit sufficiently from the transplantation.

METHODS

This single-center study retrospectively analyzed patient data from 217 deceased donor kidney transplants performed between 1998 and 2014 as part of the Eurotransplant Senior Program, where the organ donors were ≥65 years old. Depending on donor age, the groups "older donors" (OD; n = 161) and "very old donors" (VOD; n = 56) received transplants from donors aged 65 to 75 years and >75 years, respectively. Donor and recipient clinical characteristics, delayed graft function, estimated glomerular filtration rate, 1-year rejection rate, patient and graft survival, and postoperative complications were investigated.

RESULTS

Comparing VOD group vs OD group, the 1-year, 3-year, and 5-year graft survival rates were 80.4% vs 76.4%, 62.5% vs 65.8%, and 42.6% vs 57.3%, respectively. Patient survival rates after 1, 3, and 5 years were 89.3% vs 88.2%, 71.4% vs 78.2%, and 57.5% vs 71.8%, respectively. There were no significant differences between the 2 groups (graft survival P = .107; patient survival P = .126). Kidney graft function after 1, 2, and 3 years was significantly better in the OD group than in the VOD group. No differences were found regarding postoperative complications, rejection rate, and delayed graft function.

CONCLUSION

The utilization of selected kidney-grafts from donors >75 years resulted in acceptable outcomes after kidney transplantation and could expand the donor pool. In contrast to the high mortality rate during dialysis, recipients in both groups benefited from transplantation.

Virtual Reality Simulation in Peritoneal Dialysis Training: The Beginning of a New Era

Background/Aim: Peritonitis rates in peritoneal dialysis (PD) vary considerably not only across countries but also between centers in the same country. Patient education has been shown to significantly reduce infection rates but up till now training lacks standardization with patients being trained using different methods and media (e.g., illustrations, videos). As a result, patients may be insufficiently experienced in performing PD, which might be one of the causes for high peritonitis rates. To address these issues, we developed a PD training program based on virtual reality (VR). Methods: To become acquainted with the PD procedure, patients are equipped with a VR headset and controllers. They are presented with a virtual PD set, which simulates the feeling of sitting in front of a real PD set. The patient is enabled to run through the program as often as necessary to become familiarized with the whole PD procedure. The aim is to standardize, facilitate, and accelerate the individual learning process. To compare the effect of the applied training method to traditional training, a randomized controlled trial is underway. Conclusion: Previous studies on the effectiveness of learning showed that VR training applications are superior to traditional methods, such as text- or video-based training. However, no study has been undertaken in the context of dialysis. We believe that the implementation of VR training programs in clinical practice will be beneficial in improving the patient’s proficiency, and thereby the quality and safety of PD.

Kidney transplant: functional assessment with diffusion-tensor MR imaging at 3T

PURPOSE

To evaluate the feasibility of diffusion-tensor (DT) imaging at 3 T for functional assessment of transplanted kidneys.

MATERIALS AND METHODS

This study was approved by the local ethics committee; written informed consent was obtained. Between August 2009 and October 2010, 40 renal transplant recipients were prospectively included in this study and examined with a clinical 3-T magnetic resonance (MR) imager. An echo-planar DT imaging sequence was performed in coronal orientation by using five b values (0, 200, 400, 600, 800 sec/mm(2)) and 20 diffusion directions. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were determined for the cortex and medulla of the transplanted kidney. Relationships between FA, ADC, and allograft function, determined by the estimated glomerular filtration rate (eGFR), were assessed by using Pearson correlation coefficient. ADC and FA were compared between patients with good or moderate allograft function (group A; eGFR > 30 mL/min/1.73 m(2)) and patients with impaired function (group B; eGFR ≤ 30 mL/min/1.73 m(2)) by using a student t test. P < .05 indicated a statistically significant difference.

RESULTS

Mean FA of the renal medulla and cortex was significantly higher in group A (0.39 ± 0.06 and 0.17 ± 0.4) compared with group B (0.27 ± 0.05 and 0.14 ± 0.03) (P < .001 and P = .009, respectively). Mean ADCs of renal cortex and medulla were significantly higher in group A than in group B (P = .007 and P = .01, respectively). In group B, mean medullary FA was significantly lower in patients whose renal function did not recover (0.22 ± 0.02) compared with those with stable allograft function at 6 months (0.29 ± 0.05, P < .001). There was significant correlation between eGFR and medullary FA (r = 0.65, P < .001), cortical ADC (r = 0.43, P = .003), and medullary ADC (r = 0.35, P = .01).

CONCLUSION

DT imaging is a promising noninvasive technique for functional assessment of renal allografts. FA values in the renal medulla exhibit a good correlation with renal function.

Metastasis to skeletal muscle from esophageal adenocarcinoma

We report on a case of a 54-year-old man who was admitted to hospital with diffuse muscular pain and recurrent vomiting. Diagnosis of an adenocarcinoma of the esophagus was established by endosonography-guided biopsy. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed multiple nodular lesions within the skeletal musculature; CT-guided biopsy proved the metastatic origin of the primary tumor site. The report stresses the importance of CT and MRI in patients with proven or suspected metastases to skeletal muscle and provides a short overview of the literature.