CT-guided percutaneous lung biopsies in patients with haematologic malignancies and undiagnosed pulmonary lesions

Supplementary benefits of CT-guided transthoracic lung aspiration biopsy for core needle biopsy

Objective

This study aimed to investigate the diagnostic efficacy of computed tomography (CT)-guided transthoracic lung core needle biopsy combined with aspiration biopsy and the clinical value of this combined routine microbial detection.

Materials and methods

We retrospectively collected the electronic medical records, CT images, pathology, and other data of 1085 patients with sequential core needle biopsy and aspiration biopsy of the same lung lesion under CT guidance in the First Affiliated Hospital of Wenzhou Medical University from January 2016 to January 2021. GenXpert MTB/RIF detection and BD BACTEC™ Mycobacterium/fungus culture were applied to identifying the microbiological results of these patients. We then compared the positive diagnostic rate, false negative rate, and diagnostic sensitivity rate of three methods including core needle biopsy alone, aspiration biopsy alone, and both core needle biopsy and aspiration biopsy.

Results

The pathological results of cutting histopathology and aspiration of cell wax were examined for 1085 patients. The diagnostic rates of cutting and aspiration pathology were 90.1% (978/1085) and 86.3% (937/1085), respectively, with no significant difference (P > 0.05). Considering both cutting and aspiration pathologies, the diagnostic rate was significantly improved, up to 98% (1063/1085) (P < 0.001). A total of 803 malignant lesions were finally diagnosed (803/1085, 74.0%). The false negative rate by cutting pathology was 11.8% (95/803), which was significantly lower than that by aspiration biopsy [31.1% (250/803), P < 0.001]. Compared with core needle biopsy alone, the false negative rate of malignant lesions decreased to 5.6% (45/803) (P < 0.05). Next, the aspirates of the malignant lesions highly suspected of corresponding infection were cultured. The results showed that 16 cases (3.1%, 16/511) were infected with Mycobacterium tuberculosis complex, Aspergillus niger, and Acinetobacter baumannii, which required clinical treatment. 803 malignant tumors were excluded and 282 cases of benign lesions were diagnosed, including 232 cases of infectious lesions (82.3%, 232/282). The diagnostic rate of Mycobacterium/fungus culture for infectious lesions by aspiration biopsy (47.4%) was significantly higher than that by lung core needle biopsy (22.8%; P < 0.001). The diagnostic rate of aspiration biopsy combined with core needle biopsy was 56% (130/232). The parallel diagnostic rate of aspirated biopsy for GenXpert detection and Mycobacterium/fungal culture combined with core needle biopsy was 64.7% (150/232), which was significantly higher than that of lung core needle biopsy alone (P < 0.001). Finally, pulmonary tuberculosis was diagnosed in 90 cases (38.8%) of infectious lesions. Compared with the sensitivity of core needle biopsy to detect tuberculosis (27.8%, 25/90), the sensitivity of aspirating biopsy for GenXpert detection and Mycobacterium/fungal culture was significantly higher, at 70% (63/90) and 56.7% (51/90), respectively. Although there was no significant difference in the sensitivity of aspirated biopsy for GenXpert and Mycobacterium/fungal culture to detect pulmonary tuberculosis, the sensitivity was significantly increased to 83.3% (P < 0.05) when the two tests were combined. Moreover, when aspirated biopsies were combined with GenXpert detection, Mycobacterium/fungus culture, and core needle biopsy, the sensitivity was as high as 90% (81/90).

Conclusion

CT-guided lung aspiration biopsy has a significant supplementary effect on core needle biopsies, which is indispensable in clinical application. Additionally, the combination of aspiration biopsy and core needle biopsy can significantly improve the diagnostic rate of benign and malignant lesions. Aspiration biopsy showed that pulmonary malignant lesions are complicated with pulmonary tuberculosis, aspergillus, and other infections. Finally, the diagnostic ability of lung puncture core needle biopsy and aspiration biopsy combined with routine microbial detection under CT positioning in the diagnosis of pulmonary infectious diseases was significantly improved.

Efficacy and Safety of Endobronchial Ultrasonography with a Guide-sheath for Acute Pulmonary Lesions in Patients with Haematological Diseases

Objective Acute pulmonary lesions (APLs), defined as an acute infiltrate or nodular lung field, are a major complication in patients with haematological diseases. Recently, endobronchial ultrasonography with a guide-sheath (EBUS-GS) was established as a useful technique for diagnosing pulmonary lesions. This study aimed to evaluate the efficacy and safety of EBUS-GS for managing APLs in patients with haematological diseases. Methods Our single-centre, retrospective, observational, single-arm, descriptive study enrolled 22 consecutive adult (>20-year-old) patients with haematological diseases and concomitant APL who underwent EBUS-GS between January 2011 and June 2016 at Kameda Medical Center, Chiba, Japan. The primary endpoint was the contribution of EBUS-GS to clinical decision-making. Secondary endpoints were an adequate tissue collection rate, diagnostic yield, complication rate, and 30-day mortality. Results The median patient age was 70 years old, and 63.6% were men. Acute myeloid leukaemia was the most frequent underlying disease, accounting for 54.5% of patients. The contribution of EBUS-GS to clinical decision-making was recognised in 11 (50.0%) patients. Adequate tissue collection was achieved in 21 (95.5%) patients. The aetiology of the APL was identified in 9 (40.9%) patients. No complications, including severe haemorrhaging and pneumothorax, were observed in any patients, and the 30-day mortality rate was 0%. Conclusion EBUS-GS may be a suitable diagnostic option for APL in patients with haematological diseases. Further larger-scale and randomised controlled trials are needed to confirm our results.

Usefulness of CT-Guided Percutaneous Transthoracic Needle Lung Biopsies in Patients with Suspected Pulmonary Infection

Objective

This study aimed to evaluate the clinical benefits and risks of CT-guided percutaneous transthoracic needle lung biopsies (PTNBs) in patients with a suspected pulmonary infection.

Materials and Methods

This study included 351 CT-guided PTNBs performed in 342 patients (mean age, 58.9 years [range, 17–91 years]) with suspected pulmonary infection from January 2010 to December 2016. The proportion of biopsies that revealed the causative organism for pulmonary infection and that influenced patient's treatment were measured. Multivariate analyses were performed to identify factors associated with PTNB that revealed the causative organism or affected the treatment. Finally, the complication rate was measured.

Results

CT-guided PTNB revealed the causative organism in 32.5% of biopsies (114/351). The presence of necrotic components in the lesion (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.1–2.7; p = 0.028), suspected pulmonary tuberculosis (OR, 2.0; 95% CI, 1.2–3.5; p = 0.010), and fine needle aspiration (OR, 2.5; 95% CI, 1.1–5.8; p = 0.037) were factors associated with biopsies that revealed the causative organism. PTNB influenced patient's treatment in 40.7% (143/351) of biopsies. The absence of leukocytosis (OR, 1.9; 95% CI, 1.0–3.7; p = 0.049), presence of a necrotic component in the lesion (OR, 2.4; 95% CI, 1.5–3.8; p < 0.001), and suspected tuberculosis (OR, 1.7; 95% CI, 1.0–2.8; p = 0.040) were factors associated with biopsies that influenced the treatment. The overall complication rate of PTNB was 19% (65/351).

Conclusion

In patients with suspected pulmonary infection, approximately 30–40% of CT-guided PTNBs revealed the causative organism or affected the treatment. The complication rate of PTNB for suspected pulmonary infection was relatively low.

CT-guided Core-Needle Biopsy of the Lung Is Safe and More Effective than Fine-Needle Aspiration Biopsy in Patients with Hematologic Malignancies

Purpose

To evaluate the safety and diagnostic yield of CT-guided core-needle biopsy (CNB) versus fine-needle aspiration biopsy (FNAB) of lung nodules and masses in patients with hematologic malignancies (HMs).

Materials and Methods

With institutional review board approval, 166 patients were retrospectively reviewed between 2007 and 2017 who were diagnosed with leukemia, lymphoma, or myelodysplastic syndromes (with or without hematopoietic stem cell transplant) and who underwent CT-guided FNAB and/or CNB of the lung. Patient medical records, pathologic reports, and interventional biopsy reports were reviewed.

Results

In the study period, 166 patients underwent percutaneous CT-guided lung biopsy; 36% (60 of 166) of the procedures included CNB (CNB + FNAB and CNB only), whereas 64% (106 of 166) were FNAB only. In the CNB group, FNAB was also performed for 92% (55 of 60) of the patients before CNB; 13% (eight of 60) of patients in the CNB group were nondiagnostic versus 45% (48 of 106) of FNAB only (P < .0001). There was no statistically significant difference in the pulmonary complication rates, with 1.7% of CNB and 1.9% of FNAB only requiring chest tube placement (P = .7), 5% of CNB and 2.8% of FNAB only developing hemoptysis (P = .4), and 5% of CNB and 2% of FNAB only developing hemothorax (P = .3). A change in clinical management was observed in 51% of patients with diagnostic biopsies compared with 21% of patients with nondiagnostic biopsies (P = .0002).

Conclusion

CT-guided CNB is an effective technique for performing lung biopsy in patients with HMs with higher diagnostic yield compared with FNAB, and a higher, although not a statistically significant, increased risk of bleeding complications and pneumothorax.© RSNA, 2019See also the commentary by Elicker in this issue.

A bronchoalveolar lavage-driven antimicrobial treatment improves survival in hematologic malignancy patients with detected lung infiltrates: A prospective multicenter study of the SEIFEM group

Bronchoalveolar lavage (BAL) is recommended for diagnosing lung infiltrates (LI) in patients with hematologic malignancy (HM). Prospective data on the impact of BAL on survival are still lacking. We conducted a prospective observational study on patients who performed BAL for LI among 3055 HM patients hospitalized from January to September 2018. The BAL was performed in 145 out of 434 patients who developed LI, at a median time of four days from LI detection. The median age was 60 (1-83). Most patients had an acute myeloid leukemia/myelodisplastic syndrome (81), followed by lymphoma (41), acute lymphoblastic leukemia (27), and other types of HM (36). A putative causal agent was detected in 111 cases (76%), and in 89 cases (61%) the BAL results provided guidance to antimicrobial treatment. We observed a significantly improved outcome of LI at day +30 in patients who could receive a BAL-driven antimicrobial treatment (improvement/resolution rate: 71% vs 55%; P = .04). Moreover, we observed a significantly improved outcome in 120-day overall survival (120d-OS) (78% vs 59%; P = .009) and 120-day attributable mortality (120d-AM) (11% vs 30%; P = 0.003) for patients who could receive a BAL-driven treatment. The multivariate analysis showed that BAL-driven antimicrobial treatment was significantly associated with better 120d-OS and lower 120d-AM. We did not observe any severe adverse events. In conclusion BAL allows detection of a putative agent of LI in about 75% of cases, it is feasible and well tolerated in most cases, demonstrating that a BAL-driven antimicrobial treatment allows improvement of clinical outcome and survival.

Acute respiratory failure in immunocompromised adults

Acute respiratory failure occurs in up to half of patients with haematological malignancies and 15% of those with solid tumours or solid organ transplantation. Mortality remains high. Factors associated with mortality include a need for invasive mechanical ventilation, organ dysfunction, older age, frailty or poor performance status, delayed intensive care unit admission, and acute respiratory failure due to an invasive fungal infection or unknown cause. In addition to appropriate antibacterial therapy, initial clinical management aims to restore oxygenation and predict the most probable cause based on variables related to the underlying disease, acute respiratory failure characteristics, and radiographic findings. The cause of acute respiratory failure must then be confirmed using the most efficient, least invasive, and safest diagnostic tests. In patients with acute respiratory failure of undetermined cause, a standardised diagnostic investigation should be done immediately at admission before deciding whether to perform more invasive diagnostic procedures or to start empirical treatments. Collaborative and multidisciplinary clinical and research networks are crucial to improve our understanding of disease pathogenesis and causation and to develop less invasive diagnostic strategies and more targeted treatment options.

Autopsy findings in patients with acute myeloid leukemia and non-Hodgkin lymphoma in the modern era: a focus on lung pathology and acute respiratory failure

We aimed to report autopsy findings in patients with acute myeloid leukemia (AML) and non-Hodgkin lymphoma (NHL) in the modern era, and also to focus on lung pathology in the subgroup of patients with acute respiratory failure (ARF) of unknown etiology, which is associated with especially high mortality rates. Charts and autopsy reports of 107 patients (59 AML and 48 NHL) autopsied between 2003 and 2018 were reviewed. More than 50% of patients had missed major diagnoses found at autopsy with 95% of lungs displaying abnormal findings. Malignant infiltration in at least one organ was observed in about 70% of patients with either no complete remission or relapse at the time of death (n = 92) versus 20% in patients without signs of active malignancy (n = 15) (p = 0.001). In patients with ARF of unknown etiology (n = 59), the proportion of malignant lung infiltration was 27% and equilibrated with bacterial pneumonias (29%), fungal pneumonias represented 8%, and isolated alveolar damage or pulmonary edema were the only findings in 32% of patients. Overall, 85% of patients with ARF of unknown etiology had either relapsed or not achieved remission at time of death and 80% of patients with malignant lung infiltration had ARF of unknown etiology. Ninety percent of malignant infiltration and fungal infections were observed in patients with no complete remission or relapse. Autopsy remains valuable in AML and NHL patients; besides infections, malignant infiltration is a significant contributor to ARF of unknown etiology and is rarely diagnosed ante mortem.

Diagnostic Evaluation of Pulmonary Abnormalities in Patients with Hematologic Malignancies and Hematopoietic Cell Transplantation

Pulmonary complications (PC) of hematologic malignancies and their treatments are common causes of morbidity and mortality. Early diagnosis is challenging due to host risk factors, clinical instability, and provider preference. Delayed diagnosis impairs targeted treatment and may contribute to poor outcomes. An integrated understanding of clinical risk and radiographic patterns informs a timely approach to diagnosis and treatment. There is little prospective evidence guiding optimal modality and timing of minimally invasive lung sampling; however, a low threshold for diagnostic bronchoscopy during the first 24 to 72 hours after presentation should be a guiding principle in high-risk patients.

Fungal Pneumonia in Patients with Hematologic Malignancy and Hematopoietic Stem Cell Transplantation

Fungal pneumonias cause unacceptable morbidity among patients with hematologic malignancies (HM) and recipients of hematopoietic stem cell transplantation (HSCT). The high incidence of fungal pneumonias in HM/HSCT populations arises from their frequently severe, complex, and persistent immune dysfunction caused by the underlying disease and its treatment. The cytopenias, treatment toxicities, and other immune derangements that make patients susceptible to fungal pneumonia frequently complicate its diagnosis and increase the intensity and duration of antifungal therapy. This article addresses the host factors that contribute to susceptibility, summarizes diagnostic recommendations, and reviews current guidelines for management of fungal pneumonia in patients with HM/HSCT.

Management of neutropenic patients in the intensive care unit (NEWBORNS EXCLUDED) recommendations from an expert panel from the French Intensive Care Society (SRLF) with the French Group for Pediatric Intensive Care Emergencies (GFRUP), the French Society of Anesthesia and Intensive Care (SFAR), the French Society of Hematology (SFH), the French Society for Hospital Hygiene (SF2H), and the French Infectious Diseases Society (SPILF)

Neutropenia is defined by either an absolute or functional defect (acute myeloid leukemia or myelodysplastic syndrome) of polymorphonuclear neutrophils and is associated with high risk of specific complications that may require intensive care unit (ICU) admission. Specificities in the management of critically ill neutropenic patients prompted the establishment of guidelines dedicated to intensivists. These recommendations were drawn up by a panel of experts brought together by the French Intensive Care Society in collaboration with the French Group for Pediatric Intensive Care Emergencies, the French Society of Anesthesia and Intensive Care, the French Society of Hematology, the French Society for Hospital Hygiene, and the French Infectious Diseases Society. Literature review and formulation of recommendations were performed using the Grading of Recommendations Assessment, Development and Evaluation system. Each recommendation was then evaluated and rated by each expert using a methodology derived from the RAND/UCLA Appropriateness Method. Six fields are covered by the provided recommendations: (1) ICU admission and prognosis, (2) protective isolation and prophylaxis, (3) management of acute respiratory failure, (4) organ failure and organ support, (5) antibiotic management and source control, and (6) hematological management. Most of the provided recommendations are obtained from low levels of evidence, however, suggesting a need for additional studies. Seven recommendations were, however, associated with high level of evidences and are related to protective isolation, diagnostic workup of acute respiratory failure, medical management, and timing surgery in patients with typhlitis.

Diagnosis and antimicrobial therapy of lung infiltrates in febrile neutropenic patients (allogeneic SCT excluded): updated guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Up to 25% of patients with profound neutropenia lasting for >10 days develop lung infiltrates, which frequently do not respond to broad-spectrum antibacterial therapy. While a causative pathogen remains undetected in the majority of cases, Aspergillus spp., Pneumocystis jirovecii, multi-resistant Gram-negative pathogens, mycobacteria or respiratory viruses may be involved. In at-risk patients who have received trimethoprim-sulfamethoxazole (TMP/SMX) prophylaxis, filamentous fungal pathogens appear to be predominant, yet commonly not proven at the time of treatment initiation. Pathogens isolated from blood cultures, bronchoalveolar lavage (BAL) or respiratory secretions are not always relevant for the etiology of pulmonary infiltrates and should therefore be interpreted critically. Laboratory tests for detecting Aspergillus galactomannan, β-D-glucan or DNA from blood, BAL or tissue samples may facilitate the diagnosis; however, most polymerase chain reaction assays are not yet standardized and validated. Apart from infectious agents, pulmonary side-effects from cytotoxic drugs, radiotherapy or pulmonary involvement by the underlying malignancy should be included into differential diagnosis and eventually be clarified by invasive diagnostic procedures. Pre-emptive treatment with mold-active systemic antifungal agents improves clinical outcome, while other microorganisms are preferably treated only when microbiologically documented. High-dose TMP/SMX is first choice for treatment of Pneumocystis pneumonia, while cytomegalovirus pneumonia is treated primarily with ganciclovir or foscarnet in most patients. In a considerable number of patients, clinical outcome may be favorable despite respiratory failure, so that intensive care should be unrestrictedly provided in patients whose prognosis is not desperate due to other reasons.

A long-term survivor of disseminated Aspergillus and mucorales infection: an instructive case

Invasive fungal infections remain major causes of infection-related mortality in hematopoietic stem cell transplantation (HSCT) patients. Mixed infections and multiple organ involvement have been reported in these patients. Here, we report a case of mixed Aspergillus and Mucorales infection involving the lungs, brain, spleen and bone in a HSCT patient with relapsed acute myeloid leukemia, who finally improved with triple antifungal therapy and neurosurgical evacuation of brain abscesses. She was put on lifelong secondary prophylaxis with posaconazole with excellent compliance and no sign of toxicity despite over 10 years of drug administration. Serial galactomannan measurements and positron emission tomography/computed tomography were used and were helpful for disease activity monitoring. This is an instructive case of long-term survival after a severe combined mould infection.

Aspergillus PCR-based investigation of fresh tissue and effusion samples in patients with suspected invasive Aspergillosis enhances diagnostic capabilities

Although it is a severe complication in immunocompromised patients, diagnosing invasive fungal disease (IFD), especially invasive aspergillosis (IA), remains difficult. In certain clinical scenarios, examining tissue samples for identification of the infectious organism becomes important. As culture-based methods rarely yield results, the performance of an Aspergillus-specific nested PCR in fresh tissue or pleural effusion samples was evaluated. Fresh tissue (n = 59) and effusion (n = 47) specimens from 79 immunocompromised patients were subjected to an Aspergillus-specific PCR assay. Twenty-six patients had proven (n = 20) or probable (n = 6) IFD, according to the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) criteria, while the remaining patients were classified as having either possible IFD (n = 30) or no IFD (n = 23). IA was identified as the underlying IFD in 21/26 proven/probable cases. PCR positivity was observed for 18/21 proven/probable and 6 possible IA cases; cases classified as no IA did not show positive signals. Patients with proven IFD (n = 5) with cultures positive for non-Aspergillus molds also had negative Aspergillus PCR results. Aspergillus PCR performance analysis yielded sensitivity and specificity values of 86% (95% confidence interval [CI], 65% to 95%) and 100% (95% CI, 86% to 100%), respectively, thus leading to a diagnostic odds ratio of >200. In this analysis, good diagnostic performance of the PCR assay for detection of IA was observed for tissue samples, while effusion samples showed lower sensitivity rates. PCR testing represents a complementary tool; a positive PCR result strengthens the likelihood of IA, whereas IA seems unlikely in cases with negative results but findings could indicate non-Aspergillus IFD. Thus, PCR testing of these specimens enhances the diagnostic capabilities.

How I treat mucormycosis

Unlike invasive aspergillosis, the prognosis and outcome of hematologic malignancy patients who develop invasive mucormycosis have not significantly improved over the past decade as a majority of patients who develop the infection still die 12 weeks after diagnosis. However, early recognition and treatment of invasive mucormycosis syndromes, as well as individualized approaches to treatment and secondary prophylaxis, could improve the odds of survival, even in the most persistently immunosuppressed patient receiving chemotherapy and/or of stem cell transplantation. Herein, we describe the subtle clinical and radiographic clues that should alert the hematologist to the possibility of mucormycosis, and aggressive and timely treatment approaches that may limit the spread of infection before it becomes fatal. Hematology patients with this opportunistic infection require integrated care across several disciplines and frequently highly individualized and complex sequence of decision-making. We also offer perspectives for the use of 2 antifungals, amphotericin B products and posaconazole, with activity against Mucorales. The availability of posaconazole in an oral formulation that can be administered safely for prolonged periods makes it an attractive agent for long-term primary and secondary prophylaxis. However, serum drug concentration monitoring may be required to minimize breakthrough infection or relapsing mucormycosis associated with inadequate blood concentrations.

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.

The impact of imaging speed of MR-guided punctures and interventions in static organs--a phantom study

PURPOSE

Verification of MR-guidance with image acquisitions slower than 1 image per second as it is inevitable for some interventions. Therefore, we quantified solely the effect of acquisition-time on the efficiency of MR-guided interventions in a static phantom study.

MATERIALS AND METHODS

We measured the duration, accuracy and error rate of simulated interventions for different acquisition-times using a simplified interventional setup. All measurements were performed in a 1.0 T open MRI scanner. Imaging was performed with a gradient-echo sequence (flipangle=20°; TR/TE=12/6 ms; voxelsize=1 mm×1 mm; slicethickness=5 mm; FOV=230 mm×200 mm; acquisition-time=1 s). Variable acquisition times were simulated with intermediate pauses of 0, 1, 2, 3, 4 and 5 s. The interventions were performed by a total of 20 volunteers including 7 experienced interventionalists.

RESULTS

The mean duration of the intervention was 2 min. Significant differences between experienced and unexperienced volunteers were limited to the localization of the image plane and corrections made. The mean accuracy was 5.6 mm. The time to localize the image plane increased with deceleration of imaging from 24 s to 49 s. A similar increase was observed for the intervention time (55-108 s). A significant influence of the acquisition-time on durations and corrections was only found with acquisition-times greater than 4s per image.

CONCLUSION

Even image rates of several seconds per image are sufficient enough for efficient interventions in static organs. Thus, the main attention has to be turned on the visibility of the needle when sequences are optimized for MR-guidance. The minimization of imaging speed is rather of secondary interest.