Detection of pneumothorax: comparison of digital and conventional chest imaging

To investigate radiologists' performance at interpreting digital radiographic images, we compared the detectability of pneumothoraces on computed radiographic chest images with 0.2-mm pixel size (2.5 Ip/mm) with their detectability on matched conventional screen-film images (5 Ip/mm). Eight radiologists reviewed 50 computed and 50 screen-film chest radiographs from 25 patients with pneumothoraces and 25 patients with other (or no) abnormalities. Four of the readers who best detected pneumothoraces on screen-film examinations performed worse when interpreting computed radiographic studies; the other four readers detected pneumothoraces similarly with both techniques. No relationship was found between the size of a pneumothorax and its likelihood of detection by either technique. These results raise concerns about implementing computed radiography for comprehensive chest imaging.     

CT detection of occult pneumothorax in head trauma

A prospective evaluation for occult pneumothorax was performed in 25 consecutive patients with serious head trauma by combining a limited chest CT examination with the emergency head CT examination. Of 21 pneumothoraces present in 15 patients, 11 (52%) were found only by chest CT and were not identified clinically or by supine chest radiograph. Because of pending therapeutic measures, chest tubes were placed in nine of the 11 occult pneumothoraces, regardless of the volume. Chest CT proved itself as the most sensitive method for detection of occult pneumothorax, permitting early chest tube placement to prevent transition to a tension pneumothorax during subsequent mechanical ventilation or emergency surgery under general anesthesia.     

The floating cardiac fat pad—sign of occult pneumothorax

Pneumothoraces are a possible sequela of chest trauma with potential morbidity and mortality if not recognized and treated promptly. A portable supine chest radiograph is frequently the first radiologic study performed in the setting of trauma. While large pneumothoraces can be readily recognized on these radiographs, smaller pneumothoraces are missed in up to 15 % of trauma patients. There are many radiographic signs of occult pneumothoraces, and we are presenting a new radiographic sign of occult pneumothorax. The floating cardiac fat pad sign occurs when pleural air collects anteriorly and superiorly in the most non-dependent portion of the chest lifting the pericardial fat pad off the diaphragm. Lung markings are still seen surrounding the pericardial fat pad due to the inflated lower lobe of the lung resting dependently. Rapid and accurate identification of pneumothoraces is critical but often difficult on chest radiographs. Although there are many existing radiographic signs for identification of pneumothorax, prospective identification of small pneumothoraces is still relatively poor. Here, we describe an additional sign which aides in the detection of pneumothoraces, the floating cardiac fat pad. When present, this should prompt further evaluation with chest CT or upright chest radiograph.     

CT and chest radiography are equally sensitive in the detection of pneumothorax after CT-guided pulmonary interventional procedures

Pneumothorax is the most common complication after CT-guided pulmonary interventional procedures and should be promptly diagnosed and treated. Because it is easier to obtain CT scans than chest radiographs after CT-guided interventional procedures, it is important to know the sensitivity of CT in detecting pneumothoraces. To determine the sensitivity of CT for detecting procedure-induced pneumothoraces, we retrospectively reviewed 70 pulmonary interventional procedures performed under CT guidance. The sensitivity for detecting pneumothoraces with CT was compared with the detection rate with expiratory chest radiographs. Thirty-two (46%) of 70 procedures resulted in pneumothorax. Twenty-nine (91%) of the pneumothoraces were detected on CT scans and 27 (84%) were detected on chest radiographs. The difference between these two detection rates was not statistically significant (p less than .90). We conclude that postprocedure CT scans can replace expiratory chest radiographs for the detection of pneumothoraces after CT-directed pulmonary procedures.     

Outpatient Management of Postbiopsy Pneumothorax with Small-Caliber Chest Tubes: Factors Affecting the Need for Prolonged Drainage and Additional Interventions

The aim of this study was to evaluate the efficacy of outpatient management of postbiopsy pneumothoraces with small-caliber chest tubes and to assess the factors that influence the need for prolonged drainage or additional interventions. We evaluated the medical records of patients who were treated with small-caliber chest tubes attached to Heimlich valves for pneumothoraces resulting from image-guided transthoracic needle biopsy to determine the hospital admission rates, the number of days the catheters were left in place, and the need for further interventions. We also evaluated the patient, lesion, and biopsy technique characteristics to determine their influence on the need for prolonged catheter drainage or additional interventions. Of the 191 patients included in our study, 178 (93.2%) were treated as outpatients. Ten patients (5.2%) were admitted for chest tube-related problems, either for underwater suction (n = 8) or for pain control (n = 2). No further interventions were required in 146 patients (76.4%), with successful removal of the chest tubes the day after the biopsy procedure. Prolonged catheter drainage (mean, 4.3 days) was required in 44 patients (23%). Nineteen patients (9.9%) underwent additional interventions for management of pneumothorax. Presence of emphysema was noted more frequently in patients who required additional interventions or prolonged chest tube drainage than in those who did not (51.1% vs. 24.7%; p = 0.001). We conclude that use of the Heimlich valve allows safe and successful outpatient treatment of most patients requiring chest tube placement for postbiopsy pneumothorax. Additional interventions or prolonged chest tube drainage are needed more frequently in patients with emphysema in the needle path.     

Timing of chest film follow-up after transthoracic needle aspiration

Transthoracic needle aspiration of pulmonary lesions is an extremely common procedure. Pneumothorax, the most common complication, is potentially life threatening. In an effort to determine the optimum time for obtaining chest radiographs to detect pneumothorax, all cases of pneumothorax that occurred after transthoracic needle aspiration between 1981 and 1984 were reviewed. During this period, 673 transthoracic-needle-aspiration procedures were performed. Pneumothorax occurred in 160 patients (23.8%), and 78 (11.5%) of these required a chest tube or aspiration. Of the total number of pneumothoraces, 142 (89%) were detected immediately, 15 (9%) were first seen after 1 hr, and only 3 (2%) were first seen on the 4-hr radiograph. Of the pneumothoraces requiring intervention, 69 (88%) were detected immediately while the remainder were first picked up after 1 hr. There were no significant pneumothoraces detected after the 1-hr radiograph. Immediate fluoroscopy and a routine chest radiograph 1-hour postprocedure are recommended. For outpatients 1-hr and 4-hr follow-up radiographs should be taken.     

Traumatic pneumothorax detection with thoracic US: correlation with chest radiography and CT--initial experience

PURPOSE: To prospectively compare the accuracy of ultrasonography (US) with that of supine chest radiography in the detection of traumatic pneumothoraces, with computed tomography (CT) as the reference standard. MATERIALS AND METHODS: Thoracic US, supine chest radiography, and CT were performed to assess for pneumothorax in 27 patients who sustained blunt thoracic trauma. US and radiographic findings were compared with CT findings, the reference standard, for pneumothorax detection. For the purpose of this study, the sonographers were blinded to the radiographic and CT findings. RESULTS: Eleven of 27 patients had pneumothorax at CT. All 11 of these pneumothoraces were detected at US, and four were seen at supine chest radiography. In the one false-positive US case, the patient was shown to have substantial bullous emphysema at CT. Sensitivity and negative predictive value of US were 100% (11 of 11 and 15 of 15 patients, respectively), specificity was 94% (15 of 16 patients), and positive predictive value was 92% (11 of 12 patients). Chest radiography had 36% (four of 11 patients) sensitivity, 100% (16 of 16 patients) specificity, a 100% (four of four patients) positive predictive value, and a 70% (16 of 23 patients) negative predictive value. CONCLUSION: In this study, US was more sensitive than supine chest radiography and as sensitive as CT in the detection of traumatic pneumothoraces.     

Role of chest radiography after the insertion of a subclavian vein catheter for ambulatory chemotherapy.

OBJECTIVE: To determine the need for routine chest radiography after the insertion of a catheter via the subclavian vein for ambulatory chemotherapy. METHODS: The case notes of all patients who had undergone catheter insertion between 1994 and 1998 were reviewed retrospectively. RESULTS: Of 3844 cases, there were 52 (1.4%) complications detected on chest radiographs after catheter insertion, 46 of which were pneumothoraces; 15 of the 46 patients had a clinical risk factor at insertion (technical difficulty or symptoms), and 14 had a risk factor after insertion (respiratory symptoms and signs). For 22 (47.8%) pneumothoraces, there was no clinical risk factor identified; 3 of these patients required intercostal drain insertion. Other complications (n = 6) included catheter malposition and kinking, and chest radiography made an important contribution to management in at least 1 of these cases. CONCLUSION: In approximately 0.1% of cases of catheter insertion in the subclavian vein, chest radiography detected a clinically occult complication significant enough to require intervention.     

Computed tomography whole body imaging in multi-trauma: 7 years experience

AIM: To assess the impact of the introduction of a computed tomography (CT) imaging protocol for multi-trauma patients on the workload, overall diagnostic yield, and effect on detection of cervical spine injury and pneumothorax. METHOD: Between February 1997 and April 2004, all patients presenting acutely to the Emergency Department (ED) with haemodynamically stable trauma (Abbreviated Injury Scale 3 or more) involving more than two body systems were imaged with a comprehensive pre-set helical CT protocol (including non-contrast head, cervical spine: cranio-cervical and cervico-thoracic junctions; and oral and intravenous contrast-enhanced thoracic, abdomen and pelvis) after initial triage and a standard trauma series of radiographs (chest, lateral C-spine and pelvis). Diagnosis of cervical spine fracture and pneumothorax was noted before and after the CT protocol was carried out and findings from all studies were recorded prospectively. RESULTS: Over the 7-year period 296 multi-trauma CT studies were completed of which 41 (13.8%) were negative. Of the positive cases there were 127 (43%) head injuries; 25 cervical spine fractures (8%); 66 pelvic fractures (22%);48 thoracic or lumbar spine fractures (16%); 97 pneumothoraces (33%); 22 mediastinal injuries (7%) and 49 intra-abdominal injuries (17%) with 19 (6%) splenic tears/ruptures. Positive findings included many unsuspected injuries, including 19 cervical spine fractures which were not demonstrated on the standard lateral radiograph from the resuscitation room. Of the 97 CT detected pneumothoraces, 12 were bilateral, 52 already had a chest drain in situ and 36 were not detected on initial supine chest radiography in the resuscitation room. One undetected case had bilateral tension pneumothoraces that were promptly drained on the CT table. Only three patients did not complete their multi-trauma examination because of deterioration in clinical condition and these were all immediately returned to the resuscitation room. CONCLUSION: Over the 7-year period in a large acute National Health Service (NHS) hospital trust currently averaging 85,000 ED attendances per year only 296 patients fulfilled the stated criteria for an immediate multi-trauma CT study. Although disruptive in the short-term, the overall impact on workload was small. A wide range of significant injuries were demonstrated rapidly, accurately and safely, including 19 cervical spine fractures and 26 pneumothoraces not detected on plain radiographs.     

Efficacy of digital radiography for the detection of pneumothorax: comparison with conventional chest radiography.

As part of our continuing evaluation of the clinical applicability of digital radiography, we compared the abilities of radiologists to detect pneumothoraces on conventional chest radiographs with their performances when using three formats of digitally obtained images. Twenty-three frontal-view chest radiographs with pneumothoraces and 22 other chest radiographs, either normal or showing miscellaneous abnormalities, were interpreted by five experienced radiologists in each of four formats: conventional film-screen chest radiographs, small-format (17.8 x 21.6 cm) computed radiographs, large-format (35.6 x 43.1 cm) computed radiographs, and digital images viewed on an interactive electronic workstation. The receiver-operating-characteristic curve areas for each observer for the four types of images were compared by a z test on a critical ratio, and the mean sensitivity and specificity values were compared by the sign rank test. The mean areas under the receiver-operating-characteristic curves ranged from 0.869 for the digital workstation to 0.915 for film-screen images. The differences observed among formats were not statistically significant. Mean specificities also were not significantly different, ranging from 0.90 for large-format computed radiographs to 0.96 for the digital workstation. Mean sensitivity ranged from 0.65 for the digital workstation to 0.82 for film-screen images. Radiologists interpreting digital workstation images were significantly less sensitive in detecting pneumothoraces than with film-screen and small-format computed images (p = .06). In this study, radiologists detected pneumothoraces equally well on conventional film-screen radiographs and digital images printed on film; however, they detected pneumothoraces less well on electronic viewing consoles. This latter finding reflects an important practical difference in the working behavior of radiologists interacting with a digital workstation.     

MDCT quantification is the dominant parameter in decision-making regarding chest tube drainage for stable patients with traumatic pneumothorax

It is commonly believed that the size of a pneumothorax is an important determinant of treatment decision, in particular regarding whether chest tube drainage (CTD) is required. However, the volumetric quantification of pneumothoraces has not routinely been performed in clinics. In this paper, we introduced an automated computer-aided volumetry (CAV) scheme for quantification of volume of pneumothoraces in chest multi-detect CT (MDCT) images. Moreover, we investigated the impact of accurate volume of pneumothoraces in the improvement of the performance in decision-making regarding CTD in the management of traumatic pneumothoraces. For this purpose, an occurrence frequency map was calculated for quantitative analysis of the importance of each clinical parameter in the decision-making regarding CTD by a computer simulation of decision-making using a genetic algorithm (GA) and a support vector machine (SVM). A total of 14 clinical parameters, including volume of pneumothorax calculated by our CAV scheme, was collected as parameters available for decision-making. The results showed that volume was the dominant parameter in decision-making regarding CTD, with an occurrence frequency value of 1.00. The results also indicated that the inclusion of volume provided the best performance that was statistically significant compared to the other tests in which volume was excluded from the clinical parameters. This study provides the scientific evidence for the application of CAV scheme in MDCT volumetric quantification of pneumothoraces in the management of clinically stable chest trauma patients with traumatic pneumothorax.     

Evaluation of the role of chest computed tomography in the management of trauma patients

The role of chest computed tomography (CT) in the management of trauma patients is evolving. The present study reviews the chest radiographic and chest CT findings in a group of trauma patients to determine the clinical impact of findings noted exclusively on chest CT.Fifty-five trauma patients examined with chest radiography and chest CT and whose clinical charts were available for review were retrospectively identified. There were 46 men and 9 women, with a mean age of 39 years. The presence (and size) of pneumothorax, hemothorax, pulmonary contusion, and fractures was tabulated for the chest radiographs and CT scans. The presence of mediastinal widening on chest radiographs and all mediastinal findings on CT were noted. The results of aortography, when applicable, were correlated. The clinical charts were reviewed to assess the impact of CT findings on patient management.Pneumothorax (P<0.05), hemothorax (P<0.05), pulmonary contusions, and fractures were noted more frequently on chest CT than on chest radiography. However, clinical management was affected in only three (5%) of these patients. Chest CT findings related to the mediastinum affected patient management in 13 (24%) patients. CT obviated the need for aortography in 7 of 10 patients with mediastinal widening on chest radiographs. Six other patients had aortography, four for mediastinal hematoma with a normal-appearing aorta on contrast medium-enhanced CT, and two for mediastinal hematoma and aortic injury on CT.Despite detection of significantly more pneumothoraces and hemothoraces on chest CT, clinical management was affected in only a small minority (5%) of cases. CT did prove useful in evaluating the mediastinum, obviating the need for aortography in 7 of 10 patients with a widened mediastinum on chest radiography and accurately diagnosing the presence and site of aortic injury in the two patients with that diagnosis.     

Pneumothorax after lung biopsy: prevention with transpleural placement of compressed collagen foam plugs.

The effectiveness of pleural sealing with a compressed collagen foam plug in preventing the development of pneumothorax was evaluated in a prospective, comparative study of 50 patients undergoing transthoracic needle biopsies. The 4-cm-long plug was deposited through the thin-walled guidance needle at the end of the procedure in a position where it would cross both the visceral and the parietal pleura. The prevalence of postbiopsy pneumothorax was 28% (seven of 25 patients) in the control group and 8% (two of 25 patients) in the plug group. In each study group, two patients with pneumothoraces required chest tubes. Although further experience is necessary, the authors conclude that transpleural collagen foam plug placement may be an effective supplement for transthoracic needle biopsies.     

CT-guided lung biopsy: incidence of pneumothorax after instillation of NaCl into the biopsy track

This study was conducted to evaluate whether instillation of NaCl 0.9% solution into the biopsy track reduces the incidence of pneumothoraces after CT-guided lung biopsy. A total of 140 consecutive patients with pulmonary lesions were included in this prospective study. All patients were alternatingly assigned to one of two groups: group A in whom the puncture access was sealed by instillation of NaCl 0.9% solution during extraction of the guide needle (n = 70) or group B for whom no sealing was performed (n = 70). CT-guided biopsy was performed with a 18-G coaxial system. Localization of lesion (pleural, peripheral, central), lesion size, needle-pleural angle, rate of pneumothorax and alveolar hemorrhage were evaluated. In group A, the incidence of pneumothorax was lower compared to group B (8%, 6/70 patients vs. 34%, 24/70 patients; P < 0.001). All pneumothoraces occurred directly post punctionem after extraction of the guide needle. One patient in group A and eight patients in group B developed large pneumothoraces requiring chest tube placement (P = 0.01). The frequency of pneumothorax was independent of other variables. After CT-guided biopsy, instillation of NaCl 0.9% solution into the puncture access during extraction of the needle significantly reduces the incidence of pneumothorax.     

Protection of the mediastinum and chest wall with an artificial pneumothorax during lung ablations

The objective in creating an artificial pneumothorax during lung ablation is to develop a working space in the thorax sufficient to displace the target lung lesion from adjacent vulnerable mediastinal or chest wall structures. Attempts to induce a protective pneumothorax with the use of spring-loaded needles were successful in four of six patients, permitting development of safe "windows" for ablation. These pneumothoraces were induced by the introduction of a needle with a spring-loaded, blunt-tipped obturator into the pleural space, followed by injection of room air. Pleural adhesions related to previous interventions may interfere with creation of a pneumothorax. Use of this technique could extend the utility of ablative therapies for lesions adjacent to the mediastinum and chest wall.     

Percutaneous pulmonary aspiration biopsy using the Chiba needle.

The Chiba needle was used for percutaneous needle aspiration of lung lesions in 35 patients. Two separate needles were used for each patient at the same sitting. The aspirate was true positive for malignancy in 23 patients and true negative for malignancy in eight patients. Two aspirates were false negative for malignancy and two aspirates, negative for malignancy, were classified as inconclusive due to inadequate patient follow-up. The overall accuracy rate was 94%. Six patients had small pneumothoraces but only one required a chest tube. Appreciable hemoptysis did not occur. The Chiba needle provided an adequate aspirate for cytologic diagnosis. The complication rate using two needles appears to be entirely acceptable.     

Prevalence and significance of thoracic pathology first detected on the lung base images of abdominal computed tomographic scans

The purpose of this study was to examine the prevalence and significance of pathology present on the lung base images of abdominal computed tomographic (ACT) scans, but not apparent on the chest radiographs, in two distinct patient populations. The reports of 853 consecutive ACT scans performed in patients at an urban Veterans Affairs hospital (DVAMC) (mean age = 69 years) and 1152 consecutive inpatient and emergency department ACT scans performed at an inner city level I trauma center (UMDNJ) (mean age = 39 years) were reviewed retrospectively. The original images of all ACT scans for which lung base abnormalities were reported were re-interpreted by two radiologists and compared with findings on chest radiographs taken within 48 hours. The degree of correlation between the two studies was analyzed, and the clinical impact of all findings incidentally imaged on ACT but not apparent on the chest radiograph were assessed. At UMDNJ, 51 ACT reports (4.4%) and at DVAMC, 95 reports (11.1%) described lung base pathology. The most common findings at both institutions were pleural effusions, with 23 and 42 depicted at UMDNJ and DVAMC, respectively. At UMDNJ, the remaining abnormalities included 7 pneumothoraces, 5 infiltrates, 1 bleeding artery, and 1 case of multiple nodules, whereas at DVAMC, the next most frequent lower thoracic pathology findings were asbestos pleural plaques (11 patients), multiple nodules (10 patients), and solitary masses (9 patients). Lung base pathology not visible on chest radiography was present in 25 of 37 cases at UMDNJ (68%) and 38 of 89 cases at DVAMC (43%), of which a total of 19 were relevant to further patient management (30%). Three of the five such clinically relevant discrepancies at UMDNJ were pneumothoraces, and 12 of 14 at DVAMC were malignancies. Overall, 0.4% of ACT scans at UMDNJ and 1.7% at DVAMC revealed previously undetected lesions relevant to patient care (P=0.012). In certain subpopulations, especially elderly patients with known carcinomas and victims of trauma, the lung base images of ACT often present findings that may alter clinical management.     

Pneumothorax with prolonged chest tube requirement after CT-guided percutaneous lung biopsy: incidence and risk factors

Purpose

To evaluate the incidence and risk factors of pneumothoraces requiring prolonged maintenance of a chest tube following CT-guided percutaneous lung biopsy in a retrospective, single-centre case series.

Materials and methods

All patients undergoing CT-guided percutaneous lung biopsies between June 2012 and May 2014 who required chest tube insertion for symptomatic or enlarging pneumothoraces were identified. Based on chest tube dwell time, patients were divided into two groups: short term (0-2 days) or prolonged (3 or more days). The following risk factors were stratified between groups: patient demographics, target lesion characteristics, and procedural/periprocedural technique and outcomes.

Results

A total of 2337 patients underwent lung biopsy; 543 developed pneumothorax (23.2 %), 187 required chest tube placement (8.0 %), and 55 required a chest tube for 3 days or more (2.9 % of all biopsies, 29.9 % of all chest tubes). The median chest tube dwell time for short-term and prolonged groups was 1.0 days and 4.7 days, respectively. The transfissural needle path predicted prolonged chest tube requirement (OR: 2.5; p?=?0.023). Other factors were not significantly different between groups.

Conclusion

Of patients undergoing CT-guided lung biopsy, 2.9 % required a chest tube for 3 or more days. Transfissural needle path during biopsy was a risk factor for prolonged chest tube requirement.

Key Points

? CT-guided percutaneous lung biopsy (CPLB) is an important method for diagnosing lung lesions ? A total of 2.9 % of patients require a chest tube for ≥3 days following CPLB ? Transfissural needle path is a risk factor for prolonged chest tube time

     

Medial herniation of the parietal pleura: a useful sign of pneumothorax in supine neonates.

In a series of 235 consecutive infants with respiratory distress syndrome, pneumothorax was demonstrated radiographically in 20. On anteroposterior supine chest radiographs of such infants, the intrapleural gas tends to seek an anteromedial position within the involved hemithorax. When the pneumothorax is large, the gas may cause the ipsilateral mediastinal pleura to bulge and herniate across the anterior mediastinum into the contralateral hemithorax. This was seen in 12 or the 14 right pneumothoraces, but only in two of the 10 left ones. The gas-containing sac appeared radiologically as a crescent-shaped lucency medial to the upper thoracic spine which was sharply delineated laterally by the mediastinal pleural layers and the somewhat atelectatic contralateral lung. In some patients treated with a chest tube, the gas disappeared more slowly from the herniated portion of the pleural sac than from elsewhere in the pleural space. Therefore, in addition to being a useful confirmatory sign of pneumothorax, this finding is also important in assessing the completeness of pleural drainage.     

Initial assessment of chest X-ray in thoracic trauma patients: Awareness of specific injuries

AIM: To compare the reported injuries on initial assessment of the chest X-ray (CXR) in thoracic trauma patients to a second read performed by a dedicated trauma radiologist. METHODS: By retrospective analysis of a prospective database, 712 patients with an injury to the chest admitted to the University Medical Center Utrecht were studied. All patients with a CXR were included in the study. Every CXR was re-evaluated by a trauma radiologist, who was blinded for the initial results. The findings of the trauma radiologist regarding rib fractures, pneumothoraces, hemothoraces and lung contusions were compared with the initial reports from the trauma team, derived from the original patient files. RESULTS: A total of 516 patients with both thorax trauma and an initial CXR were included in the study. After re-evaluation of the initial CXR significantly more lung contusions (53.3% vs 34.1%, P < 0.001), hemothoraces (17.8% vs 11.0%, P < 0.001) and pneumothoraces (34.4% vs 26.4%, P < 0.001) were detected.During initial assessment significantly more rib fractures were reported (69.8% vs 62.3%, P < 0.001). CONCLUSION: During the initial assessment of a CXR from trauma patients in the emergency department, a significant number of treatment-dictating injuries are missed. More awareness for these specific injuries is needed.