Parametric response mapping as an indicator of bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

Late effects of blood and marrow transplantation

Hematopoietic cell transplantation is a curative treatment for a variety of hematologic diseases. Advances in transplantation technology have reduced early transplant-related mortality and expanded application of transplantation to older patients and to a wider variety of diseases. Management of late effects after transplantation is increasingly important for a growing number of long-term survivors that is estimated to be half a million worldwide. Many studies have shown that transplant survivors suffer from significant late effects that adversely affect morbidity, mortality, working status and quality of life. Late effects include diseases of the cardiovascular, pulmonary, and endocrine systems, dysfunction of the thyroid gland, gonads, liver and kidneys, infertility, iron overload, bone diseases, infection, solid cancer, and neuropsychological effects. The leading causes of late mortality include recurrent malignancy, lung diseases, infection, secondary cancers and chronic graft-versus-host disease. The aim of this review is to facilitate better care of adult transplant survivors by summarizing accumulated evidence, new insights, and practical information about individual late effects. Further research is needed to understand the biology of late effects allowing better prevention and treatment strategies to be developed.

Age and Small Airway Imaging Abnormalities in Subjects with and without Airflow Obstruction in SPIROMICS

RATIONALE

Aging is associated with reduced FEV1 to FVC ratio (FEV1/FVC), hyperinflation, and alveolar enlargement, but little is known about how age affects small airways.

OBJECTIVES

To determine if chest computed tomography (CT)-assessed functional small airway would increase with age, even among asymptomatic individuals.

METHODS

We used parametric response mapping analysis of paired inspiratory/expiratory CTs to identify functional small airway abnormality (PRMFSA) and emphysema (PRMEMPH) in the SPIROMICS (Subpopulations and Intermediate Outcome Measures in COPD Study) cohort. Using adjusted linear regression models, we analyzed associations between PRMFSA and age in subjects with or without airflow obstruction. We subdivided participants with normal spirometry based on respiratory-related impairment (6-minute-walk distance <350 m, modified Medical Research Council ≥2, chronic bronchitis, St. George's Respiratory Questionnaire >25, respiratory events requiring treatment [antibiotics and/or steroids or hospitalization] in the year before enrollment).

MEASUREMENTS AND MAIN RESULTS

Among 580 never- and ever-smokers without obstruction or respiratory impairment, PRMFSA increased 2.7% per decade, ranging from 3.6% (ages 40-50 yr) to 12.7% (ages 70-80 yr). PRMEMPH increased nonsignificantly (0.1% [ages 40-50 yr] to 0.4% [ages 70-80 yr]; P = 0.34). Associations were similar among nonobstructed individuals with respiratory-related impairment. Increasing PRMFSA in subjects without airflow obstruction was associated with increased FVC (P = 0.004) but unchanged FEV1 (P = 0.94), yielding lower FEV1/FVC ratios (P < 0.001). Although emphysema was also significantly associated with lower FEV1/FVC (P = 0.04), its contribution relative to PRMFSA in those without airflow obstruction was limited by its low burden.

CONCLUSIONS

In never- and ever-smokers without airflow obstruction, aging is associated with increased FVC and CT-defined functional small airway abnormality regardless of respiratory symptoms.

Classification systems for chronic graft-versus-host disease

Chronic graft versus host disease (GVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Clinically, chronic GVHD is a pleiotropic, multiorgan syndrome involving tissue inflammation and fibrosis that often results in permanent organ dysfunction. Chronic GVHD is fundamentally caused by replacement of the host's immune system with donor cells, although the heterogeneity of clinical manifestations suggests that patient, donor, and transplant factors modulate the phenotype. The diagnosis of chronic GVHD and determination of treatment response largely rely on clinical examination and patient interview. The 2005 and 2014 National Institutes of Health Consensus Development Projects on Criteria for Clinical Trials in Chronic GVHD standardized the terminology around chronic GVHD classification systems to ensure that a common language and procedures are being used in clinical research. This review provides a summary of these recommendations and illustrates how they are being used in clinical research and the potential for their use in clinical care.

How I treat bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

In past years, a diagnosis of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic cell transplant (HCT) conferred nearly universal mortality secondary to lack of consensus for diagnostic criteria, poorly understood disease pathogenesis, and very few studies of therapeutic or supportive care interventions. Recently, however, progress has been made in these areas: revised consensus diagnostic guidelines are now available, supportive care has improved, there is greater understanding of potential mechanisms of disease, and prospective trials are being conducted. This article describes these advances and provides suggestions to optimize therapy for patients with BOS after HCT.

Parametric Response Mapping of Bronchiolitis Obliterans Syndrome Progression After Lung Transplantation

Bronchiolitis obliterans syndrome (BOS) remains a major complication after lung transplantation. Air trapping and mosaic attenuation are typical radiological features of BOS; however, quantitative evaluation remains troublesome. We evaluated parametric response mapping (PRM, voxel-to-voxel comparison of inspiratory and expiratory computed tomography [CT] scans) in lung transplant recipients diagnosed with BOS (n = 20) and time-matched stable lung transplant recipients (n = 20). Serial PRM measurements were performed prediagnosis, at time of BOS diagnosis, and postdiagnosis (T_pre , T₀ , and T_post , respectively), or at a postoperatively matched time in stable patients. PRM results were correlated with pulmonary function and confirmed by microCT analysis of end-stage explanted lung tissue. Using PRM, we observed an increase in functional small airway disease (fSAD), from T_pre to T₀ (p = 0.006) and a concurrent decrease in healthy parenchyma (p = 0.02) in the BOS group. This change in PRM continued to T_post , which was significantly different compared to the stable patients (p = 0.0002). At BOS diagnosis, the increase in fSAD was strongly associated with a decrease in forced expiratory volume in 1 s (p = 0.011). Micro-CT confirmed the presence of airway obliteration in a sample of a BOS patient identified with 67% fSAD by PRM. We demonstrated the use of PRM as an adequate output to monitor BOS progression in lung transplant recipients.

Value of Screening Spirometry for Early Diagnosis of Bronchiolitis Obliterans Syndrome in Children After Allogeneic Hematopoietic Stem Cell Transplantation

Bronchiolitis obliterans syndrome (BOS) is a chronic graft-versus-host disease that occurs in the lungs after hematopoietic stem cell transplantation (HSCT). Serial screening pulmonary function test (PFT) is recommended after transplantation for early diagnosis of BOS. However, little is known about the value or the optimum methods of serial PFT in this context. One hundred and 10 consecutive patients of 6 to 17 years of age at the time of transplantation who underwent allogeneic HSCT were recruited for this study. Screening PFTs were performed 1 week before transplantation and 3, 6, 9, and 12 months after transplantation. When findings of obstructive lung disease were found on PFT, chest high-resolution computed tomography was performed. Of the 110 patients, 5 (4.5%) developed BOS. Of the 5 patients who developed BOS, 2 patients were diagnosed early by screening PFT. However, screening PFT did not allow for early diagnosis of BOS in the other 3 patients because BOS developed after 12 months of transplantation, which is beyond the PFT screening period. In conclusion, trimonthly PFTs performed through 12 months after transplantation in patients who underwent allogeneic HSCT helped in the early diagnosis of BOS; however, there are some limitations to this screening protocol. Future studies will aid in the development of a new screening protocol that can subsequently be evaluated.

The Impact of Sources of Variability on Parametric Response Mapping of Lung CT Scans

Parametric response mapping (PRM) of inspiration and expiration computed tomography (CT) images improves the radiological phenotyping of chronic obstructive pulmonary disease (COPD). PRM classifies individual voxels of lung parenchyma as normal, emphysematous, or nonemphysematous air trapping. In this study, bias and noise characteristics of the PRM methodology to CT and clinical procedures were evaluated to determine best practices for this quantitative technique. Twenty patients of varying COPD status with paired volumetric inspiration and expiration CT scans of the lungs were identified from the baseline COPDGene cohort. The impact of CT scanner manufacturer and reconstruction kernels were evaluated as potential sources of variability in PRM measurements along with simulations to quantify the impact of inspiration/expiration lung volume levels, misregistration, and image spacing on PRM measurements. Negligible variation in PRM metrics was observed when CT scanner type and reconstruction were consistent and inspiration/expiration lung volume levels were near target volumes. CT scanner Hounsfield unit drift occurred but remained difficult to ameliorate. Increasing levels of image misregistration and CT slice spacing were found to have a minor effect on PRM measurements. PRM-derived values were found to be most sensitive to lung volume levels and mismatched reconstruction kernels. As with other quantitative imaging techniques, reliable PRM measurements are attainable when consistent clinical and CT protocols are implemented.

National Institutes of Health Consensus Development Project on Criteria for Clinical Trials in Chronic Graft-versus-Host Disease: V. The 2014 Ancillary Therapy and Supportive Care Working Group Report

The 2006 National Institutes of Health (NIH) Consensus paper presented recommendations by the Ancillary Therapy and Supportive Care Working Group to support clinical research trials in chronic graft-versus-host disease (GVHD). Topics covered in that inaugural effort included the prevention and management of infections and common complications of chronic GVHD, as well as recommendations for patient education and appropriate follow-up. Given the new literature that has emerged during the past 8 years, we made further organ-specific refinements to these guidelines. Minimum frequencies are suggested for monitoring key parameters relevant to chronic GVHD during systemic immunosuppressive therapy and, thereafter, referral to existing late effects consensus guidelines is advised. Using the framework of the prior consensus, the 2014 NIH recommendations are organized by organ or other relevant systems and graded according to the strength and quality of supporting evidence.

NIH Consensus development project on criteria for clinical trials in chronic graft-versus-host disease: II. The 2014 Pathology Working Group Report

The 2005 National Institute of Health (NIH) Consensus Conference outlined histopathological diagnostic criteria for the major organ systems affected by both acute and chronic graft-versus-host disease (GVHD). The 2014 Consensus Conference led to this updated document with new information from histopathological studies of GVHD in the gut, liver, skin, and oral mucosa and an expanded discussion of GVHD in the lungs and kidneys. The recommendations for final histological diagnostic categories have been simplified from 4 categories to 3: no GVHD, possible GVHD, and likely GVHD, based on better reproducibility achieved by combining the previous categories of "consistent with GVHD" and "definite GVHD" into the single category of "likely GVHD." Issues remain in the histopathological characterization of GVHD, particularly with respect to the threshold of histological changes required for diagnostic certainty. Guidance is provided for the incorporation of biopsy information into prospective clinical studies of GVHD, particularly with respect to biomarker validation.

Biopsy-verified bronchiolitis obliterans and other noninfectious lung pathologies after allogeneic hematopoietic stem cell transplantation

Bronchiolitis obliterans (BO) is a serious complication of allogeneic hematopoietic stem cell transplantation (HSCT). Lung biopsy is the gold standard for diagnosis. This study describes the course of BO and assesses the congruity between biopsy-verified BO and a modified version of the National Institutes of Health's consensus criteria for BO syndrome (BOS) based exclusively on noninvasive measures. We included 44 patients transplanted between 2000 and 2010 who underwent lung biopsy for suspected BO. Of those, 23 were diagnosed with BO and 21 presented other noninfectious pulmonary pathologies, such as cryptogenic organizing pneumonia, diffuse alveolar damage, interstitial pneumonia, and nonspecific interstitial fibrosis. Compared with patients with other noninfectious pulmonary pathologies, BO patients had significantly lower values of forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity, and maximal mid-expiratory flow throughout follow-up, but there was no difference in the change in pulmonary function from the time of lung biopsy. The BO diagnosis was not associated with poorer overall survival. Fifty-two percent of patients with biopsy-verified BO and 24% of patients with other noninfectious pulmonary pathology fulfilled the BOS criteria. Pathological BO diagnosis was not superior to BOS criteria in predicting decrease in pulmonary function beyond the time of biopsy. A lung biopsy may provide a characterization of pathological patterns that can extend our knowledge on the pathophysiology of HSCT-related lung diseases.