Bacterial pneumonia following bone marrow transplantation: HRCT findings

Role of HRCT Chest in Post Stem Cell Transplant Recipients Suspected of Pulmonary Complications

INTRODUCTION

Stem cell transplantation is today's procedure of choice for management of various hematopoietic malignant and severe immunogenic disorders. High Resolution Computed Tomography (HRCT) is a common technique for the diagnosis of pulmonary complications in stem cell transplant recipients. There are a large number of complications which can complicate the post-transplant period.

AIM

To study the role of HRCT chest in stem cell transplant patients developing pulmonary complications, detect any evidence of infection, detect clinical signs of lung infections, Graft versus Host Disease (GvHD) or other regimen related toxicities outlined earlier, detect any evidence of GvHD and correlate these clinical signs with radiological changes in the lungs.

MATERIALS AND METHODS

The study was a prospective study of 52 participants with indication of stem cell transplantation. The study included recipients of HSCT transplant and the exclusion criteria was patients who failed for engraftment and having an associated history of pulmonary embolism. Patients were screened for pre-transplant chemotherapy, clinical examination, laboratory investigations including blood and biochemical examinations, imaging by ultrasound, chest radiography, baseline HRCT and a follow-up for post-transplant infections and complications with 16 slice Siemens CT scan. Statistical analysis was done using Pearson's chi-squared test.

RESULTS

Four patients among the total 56 were excluded due to non-engraftment. The most common associated findings in decreasing order are (these patients died): consolidation, pancytopenia and gastrointestinal tract symptoms with VOD (Veno-Occlusive Disease). These findings were seen on HRCT as consolidation, cavities, ground glass opacities, fibrotic changes, bronchiectatic changes and tree in bud appearance.

CONCLUSION

The study highlights the significant positive findings on the HRCT which were missed on routine chest radiograph and can be used for early diagnoses. Thus, HRCT helped in decreasing the mortality. The abnormal vitals and TLC counts showed a significant relation between the numbers of death in the study.

Infections Caused by Stenotrophomonas maltophilia in Recipients of Hematopoietic Stem Cell Transplantation

Stenotrophomonas maltophilia (S. maltophilia) is a globally emerging Gram-negative bacillus that is widely spread in environment and hospital equipment. Recently, the incidence of infections caused by this organism has increased, particularly in patients with hematological malignancy and in recipients of hematopoietic stem cell transplantation (HSCT) having neutropenia, mucositis, diarrhea, central venous catheters or graft versus host disease and receiving intensive cytotoxic chemotherapy, immunosuppressive therapy, or broad-spectrum antibiotics. The spectrum of infections in HSCT recipients includes pneumonia, urinary tract and surgical site infection, peritonitis, bacteremia, septic shock, and infection of indwelling medical devices. The organism exhibits intrinsic resistance to many classes of antibiotics including carbapenems, aminoglycosides, most of the third-generation cephalosporins, and other β-lactams. Despite the increasingly reported drug resistance, trimethoprim-sulfamethoxazole is still the drug of choice. However, the organism is still susceptible to ticarcillin-clavulanic acid, tigecycline, fluoroquinolones, polymyxin-B, and rifampicin. Genetic factors play a significant role not only in evolution of drug resistance but also in virulence of the organism. The outcome of patients having S. maltophilia infections can be improved by: using various combinations of novel therapeutic agents and aerosolized aminoglycosides or colistin, prompt administration of in vitro active antibiotics, removal of possible sources of infection such as infected indwelling intravascular catheters, and application of strict infection control measures.

A high resolution computer tomography scoring system to predict culture-positive pulmonary tuberculosis in the emergency department

This study evaluated the use of high-resolution computed tomography (HRCT) to predict the presence of culture-positive pulmonary tuberculosis (PTB) in adult patients with pulmonary lesions in the emergency department (ED). The study included a derivation phase and validation phase with a total of 8,245 patients with pulmonary disease. There were 132 patients with culture-positive PTB in the derivation phase and 147 patients with culture-positive PTB in the validation phase. Imaging evaluation of pulmonary lesions included morphology and segmental distribution. The post-test probability ratios between both phases in three prevalence areas were analyzed. In the derivation phase, a multivariate analysis model identified cavitation, consolidation, and clusters/nodules in right or left upper lobe (except anterior segment) and consolidation of the superior segment of the right or left lower lobe as independent positive factors for culture-positive PTB, while consolidation of the right or left lower lobe (except superior segment) were independent negative factors. An ideal cutoff point based on the receiver operating characteristic (ROC) curve analysis was obtained at a score of 1. The sensitivity, specificity, positivity predictive value, and negative predictive value from derivation phase were 98.5% (130/132), 99.7% (3997/4008), 92.2% (130/141), and 99.9% (3997/3999). Based on the predicted positive likelihood ratio value of 328.33 in derivation phase, the post-test probability was observed to be 91.5% in the derivation phase, 92.5% in the validation phase, 94.5% in a high TB prevalence area, 91.0% in a moderate prevalence area, and 76.8% in moderate-to-low prevalence area. Our model using HRCT, which is feasible to perform in the ED, can promptly diagnose culture-positive PTB in moderate and moderate-to-low prevalence areas.

How I manage pulmonary nodular lesions and nodular infiltrates in patients with hematologic malignancies or undergoing hematopoietic cell transplantation

Pulmonary nodules and nodular infiltrates occur frequently during treatment of hematologic malignancies and after hematopoietic cell transplantation. In patients not receiving active immunosuppressive therapy, the most likely culprits are primary lung cancer, chronic infectious or inactive granulomata, or even the underlying hematologic disease itself (especially in patients with lymphoma). In patients receiving active therapy or who are otherwise highly immunosuppressed, there is a wider spectrum of etiologies with infection being most likely, especially by bacteria and fungi. Characterization of the pulmonary lesion by high-resolution CT imaging is a crucial first diagnostic step. Other noninvasive tests can often be useful, but invasive testing by bronchoscopic evaluation or acquisition of tissue by one of several biopsy techniques should be performed for those at risk for malignancy or invasive infection unless contraindicated. The choice of the optimal biopsy technique should be individualized, guided by location of the lesion, suspected etiology, skill and experience of the diagnostic team, procedural risk of complications, and patient status. Although presumptive therapy targeting the most likely etiology is justified in patients suspected of serious infection while evaluation proceeds, a structured evaluation to determine the specific etiology is recommended. Interdisciplinary teamwork is highly desirable to optimize diagnosis and therapy.

Does high-resolution CT has diagnostic value in patients presenting with respiratory symptoms after hematopoietic stem cell transplantation?

BACKGROUND

Hematopoietic stem cell transplantation (SCT) can be complicated by a variety of live-threatening infectious and non-infectious pulmonary complications. The management of these complications is critically dependent on the most probable diagnosis, which is in part based on imaging work-up.

METHODS

Systematic review of the literature related to the diagnostic value of high-resolution computed tomography (HRCT) in patients who underwent SCT and developed respiratory symptoms.

RESULTS

Literature review did not reveal systematic cohort studies that included patients with respiratory symptoms post-SCT who underwent HRCT and had a well-defined outcome. Most studies selected participants based on their final diagnosis instead of the indication for diagnostic testing in practice. Nevertheless, several papers clearly indicated a potential role for HRCT when complications after SCT occur. A variety of articles described the role of certain HRCT findings in the diagnosis of specific infectious complications, but less data were available for non-infectious complications.

CONCLUSION

We believe more diagnostic studies are needed to determine the value of HRCT for a specific diagnosis in SCT-recipients who present with respiratory symptoms at the transplant clinic. Currently, radiologists should be cautious since HRCT interpretation in these patients is not unambiguous.