The role of multi slice computed tomography in the evaluation of acute non-cardiac chest pain

Introduction: Differential diagnosis of acute chest pain encompasses a broad spectrum of illnesses which are most likely followed by benign outcomes (pneumonia, pneumothorax, pleurisy, pericardial effusion, hiatus hernia), but also illnesses of lethal outcomes (pulmonary embolism, myocardial infarction, aortic dissection, thoracic aortic aneurysms, thoracic aortic aneurysm rupture, etc). Illnesses associated with benign and lethal outcomes may present very similar if not the same symptoms, resulting in a diffi cult establishment of accurate diagnosis. Methods: During the period of one year, 123 patients presented with non-cardiac acute chest pain were referred for the multi slice computed tomography (MSCT) examination. Scanning of thorax was conducted in two series: unenhanced and contrast-enhanced, using a window for pulmonary parenchyma and mediastinum. Results: From a total number of patients 21.1% had normal results while the other 79.9% had pathological results. Out of the total number of patients with pathological result MSCT established potentially lethal outcome for 35.0%, out of which 83.7% was contributed to vascular territory of pulmonary artery, while 16.3% was contributed to aorta. Conclusion: MSCT scanning, owe to its ability of simultaneous analysis of vascular and non-vascular thoracic structures, represents a very effi cient and reliable method for establishing accurate diagnosis and appropriate triage of patients with acute chest pain. Accurate and effi cient diagnosis enables benefi cial outcome for the patient in this group of illness. MSCT enables the differentiation of etiological factors, which present as acute onset of non-cardiac chest pain. © 2012 All rights reserved


Introduction
Many patient admissions to Emergency Department are due to acute chest pain (1,2).Diff erential diagnosis of acute chest pain encompasses a broad spectrum of illnesses which are most likely followed by benign outcomes (pneumonia, pneumothorax, pleurisy, pericardial eff usion, hiatus hernia), but also illnesses of lethal outcomes (pulmonary embolism, myocardial infarction, aortic dissection, thoracic aortic aneurysms, thoracic aortic aneurysm rupture, etc).Illnesses associated with benign and lethal outcomes may present very similar if not the same symptoms, resulting in a diffi cult establishment of accurate diagnosis (2,3).Specialist in the fi eld of emergency medicine can utilize a number of methods (anamnesis, systematic examination, chest X-ray, ECG, biological markers: troponin, CK-MB, D-dimmer) to diagnose chest pain and accurately identify the cause or contributing factors.However, in some cases these tests are insuffi cient in identifying a cause, and consequently leading to low confi dence in establishing accurate diagnosis.Specialist oft en resort to repetition of the same tests, which leads to mismanagement of time and resource, resulting in an expensive investigation which oft en delays the initiation of the appropriate treatment and the healing process for the patient (2,4).Numerous researchers consider MSCT, owning to its ability of simultaneously analyzing all vascular and non vascular thoracic structures, as a very effi cient and reliable tool for establishing accurate diagnosis and appropriate triage of patients with acute chest pain, resulting in a better outcome (1,2,3,5).
In this study we present causes of non-cardiac acute chest pain established by the MSCT.

Methods
In this study, conducted over 12 month period (January-December 2011), 123 patients were triaged by emergency department as having acute non-cardiac chest pain.All the patients admitted to the clinic, had the same medical conduct which entailed thorough anamnesis, systematic examination, ECG, and the laboratory analysis of urea, creatinine, and biological markers: troponin, CK-MB, D-dimmer.Patients with pathological ECG, elevated levels of troponin and CK-MB were eliminated from the study.Likewise, patients with elevated levels of urea and creatinine, and patients with anamnesis which included known allergic reaction to iodine contrast were also eliminated from the study mainly due to inability of administering the contrast intravenously.Patients who were included into the study were of diff erent ages: the youngest patient was 18 years old and the making the average age of the patient 54.4.Out of the total number of patients 46.3% (n=57) were females, while the remaining 53.7% (n=66) were males.Immediately prior to MSCT scanning, patients did not undergo any specifi c preparation.All the MSCT scans were performed using GE BrightSpeed 4-slice and GE LightSpeed VCT 64-slice in supine position (General Electric Company, Fairfi eld, Connecticut, USA).On acquired coronal topogram scanning fi eld was planned so that it encompasses the whole of thorax, from the level of fi rst rib to the level of the diaphragm.Scanning of thorax was initially conducted in native serial progression, following intravenous administration of contrast; scanning was conducted using a window for pulmonary parenchyma and mediastinum.Patients were instructed to hold their breath prior to the onset of scanning.Iodine contrast (Ultravist 370, Schering, Germany) was administered via automatic injector; quantity and application speed was adjusted to the age and body weight of each patient.Th e waiting period was determined using "smart preparation technique".During analysis of scanned images MPR, MIP and volume rendering techniques were used.

Results
All 123 patients were successfully examined.Acquired scanning images were satisfactory in quality and suitable for analysis and establishment of diagnosis.Out of the total 123 patients, 8 were unable to hold their breath during the scanning time, which created minor artifacts on the scanning images; however, this did not prevent images to be used in analysis Due to its ability to quickly scan the entire chest area, the MSCT is regarded universal diagnostic instrument for the evaluation of acute chest pain (4,6,7).Apart from the evaluation of pulmonary parenchyma, pleural and pericardial spaces and thoracic part of gastrointestinal tract, the contrast enhanced angiography phase of scanning enables for analysis of coronary and pulmonary arteries, as well as thoracic aorta via MSCT (6)(7)(8).Th e greatest proportion of cases with potentially lethal noncardiac related acute chest pain is in fact related to pathology of pulmonary arteries and aorta (6)(7)(8).
In this study pulmonary embolism was identifi ed to be the most common, potentially lethal cause of acute chest pain.MSCT is a golden standard in diagnosis of acute pulmonary embolism, and as a fi rst-line imaging modality it has replaced previously used conventional pulmonary angiography and ventilation -perfusion scintigraphy (9)(10)(11).
On the other hand, the greatest number of patients with normal results was referred for MSCT scanning under preliminary diagnosis of pulmonary embolism.Th is diagnosis is most probably related to the fact that the positive D-dimmer test is not specifi c enough to establish accurate diagnosis of pulmonary embolism.Th is, together with inadequate assessment of risk factors (such as immobilization, malignant illnesses, conditions related to MSCT scanning can therefore be exposed to a risk of misuse as a more of a screening rather than diagnostic test.Th is type of negligent practice is directly related to non eff ective use of this resource, which leads to increased costs of health care and unnecessary exposure of patients to radiation and iodine contrast medium (fi g. 3) (11,12).Acute thoracic aortic dissection is a life threatening condition that requires immediate diagnosis and treatment and is the most common cause of aortic emergency.Due to the fact that MSCT sensitivity and specifi city is almost 100% accurate in diagnosis of acute aortic dissection, this method should therefore be used as a fi rst-line of diagnostic tests that should be performed as soon as acute dissection of thoracic aorta is suspected (13,14).MSCT enables not only the detection of dissection of the thoracic aorta, but also provides the information necessary for classifi cation according to the Stanford system.MSCT also diff erentiates between true and false lumen, which is very important from the perspective of furthering our abilities in the fi eld of endovascular treatment (13,14).In this study all the cases of thoracic aortic dissection fall within the category "A" according to Stanford classifi cation system (Figure 4).In the case of aneurism of thoracic aorta, and in particular the rupture of aortic aneurism as a most serious related complication which requires immediate prompt and aggressive treatment, MSCT angiography is the preferred method for the evaluation of these cases (15,16).Th is method enables a total analysis of thoracic aorta aneurism; more specifi cally, it enables detailed morphology, expansion, relation to nearby structures and branches, exact location of rupture and associated measurements necessary for undertaking of endovascular treatment (15,16).In this study one case of rupture of aneurism of thoracic aorta was diagnosed.Successful MSCT angiography provided results for accurate and effi cient diagnosis which resulted in the endovascular treatment of the patient (fi g. 5).Spontaneous rupture of the diaphragm is a rare cause of acute chest pain.Although the initial method for evaluating of this condition is chest X ray, MSCT is a method of choice due to its coronal and sagittal reconstruction ability.MSCT scanning in emergency cases enables not only diagnosis of rupture but also the analysis of the herniated contents in thoracic area and possible subsequent pathological conditions in the chest (17,18).In this study we diagnosed two cases of spontaneous rupture of left hemi-diaphragm with consequential herniation of intestine into the left hemi-thorax.Patients were successfully treated through necessary surgery (fi g. 6).
In this study most oft en acute chest pain with probable benign outcome was identifi ed via MSCT in patients suff ering from infl ammatory changes in the lungs and pleura, spontaneous pneumothorax, hiatus hernia and pericardial eff usion.Th e importance of MSCT scanning is not only refl ected in the fact that these conditions were accurately diagnosed, furthermore diff erentiation between this group of pathological conditions and conditions requiring immediate attentions

Conclusion
MSCT scanning, owning to its ability of simultaneously analyzing vascular and non vascular thoracic structures represents a very effi cient and reliable method for establishing accurate diagnosis and appropriate triage of patients with acute chest pain.Accurate and effi cient diagnosis enables benefi cial outcomes for the patient in this group of illness.MSCT enables the diff erentiation of etiological factors which present as acute onset of non cardio vascular chest pain that may lead to a benign or lethal outcome.Because of all the previously mentioned advantages, MSCT should be a fi rst choice method in evaluating acute noncardiac chest pain which is more sensitive and specifi c in comparison to more conventional physiological, laboratory or other radiological methods.
SANDRA VEGAR-ZUBOVIĆ, SPOMENKA KRISTIĆ: THE ROLE OF MULTI SLICE COMPUTED TOMOGRAPHY IN THE EVALUATION OF ACUTE NON-CARDIAC CHEST PAIN

FIGURE 3 .
FIGURE 3. Massive pulmonary embolism: thrombotic masses in both pulmonary arteries

FIGURE 7 . 8 .
FIGURE 7. Spontaneous pneumothorax with large bullae FIGURE 8. Hiatus hernia as the cause of acute non-cardiac chest pain