Diaphragmatic injuries after blunt trauma: are they still a challenge?

Emerg Radiol (2012) 19:225 235 DOI 10.1007/s10140-012-1025-4 REVIEW ARTICLE Diaphragmatic injuries after blunt trauma: are they still a challenge? Reviewing CT findings and integrated imaging Giorgio Bocchini & Franco Guida & Giacomo Sica & Umberto Codella & Mariano Scaglione Received: 22 December 2011 / Accepted: 23 January 2012 / Published online: 24 February 2012 # Am Soc Emergency Radiol 2012 Abstract Traumatic diaphragmatic rupture is a lifethreatening injury that may occur in patients with blunt trauma. At present, supine chest radiographs is the initial, most commonly performed imaging test to evaluate a traumatic injury of the thorax. However, computed tomography (CT) is the imaging tool of choice, as it is the gold standard for the detection of diaphragmatic injury after trauma. In particular, recent literature indicates that multidetector CT with multiplanar reformations has significantly improved in accuracy. Radiologists working in the emergency room should keep in mind the possibility of diaphragmatic injuries and should routinely integrate the axial images CT with multiplanar reformations in order to detect any potential, subtle or doubtful sign of incomplete diaphragmatic injury. Keywords Diaphragm. Trauma. Chest radiograph. CT. MR. Clinical effectiveness Introduction Traumatic diaphragmatic rupture (TDR) is an uncommon but severe injury that can result from blunt or penetrating trauma. Prompt detection and subsequent surgical repair are essential to prevent life-threatening abdominal organ herniation into the chest cavity. Diagnosis of diaphragmatic injuries is often difficult because signs may not show up on X-rays, they may resemble other conditions or may even be absent. In most cases, the diaphragmatic rupture occurs G. Bocchini : F. Guida : G. Sica : U. Codella : M. Scaglione (*) Department of Diagnostic Imaging, Pineta Grande Medical Center, Via Domiziana Km. 30, Castel Volturno 81030, Italy e-mail: mscaglione@tiscalinet.it in combination with multiorgan injuries that may divert attention from addressing diaphragmatic disease, while subjecting the patient to a different therapeutic management. Chest radiographs are the most commonly performed imaging study to evaluate traumatic injury of the thorax in the primary survey; however, computed tomography (CT) is the gold standard for the detection of diaphragmatic injury after high kinetic energy trauma. A careful review of the literature suggests that diagnostic CT accuracy has significantly improved with advances in modern technology. Radiologists should keep in mind the possibility of diaphragmatic injuries in multitrauma patients and should routinely integrate the axial CT images with multiplanar reformations (MPRs), in order to detect any potential, subtle or doubtful sign of diaphragmatic injury. Types and mechanisms of traumatic rupture of the diaphgram TDR may be caused by blunt trauma or penetrating injuries, representing 80 85% and 15 20% of traumatic causes, respectively [1 6]. Diaphragmatic lesions originating from blunt trauma, most often resulting from motor vehicle collisions and/or high kinetic energy traumas, are less frequent and found in 0.5 8.0% of patients undergoing emergency exploratory laparotomy. Penetrating trauma is reported to be the most common cause of diaphragmatic injuries (blunt vs. penetrating01:2). In a few cases, TDR may be classified as due to iatrogenic causes [1 6]. There are various theories about the mechanism of TDR [1 10]. Raised intra-abdominal pressure is a well-accepted mechanism for blunt injury. Under normal conditions, the intra-abdominal pressure measures +2 cm H 2 O, reaching a value of +10 cm H 2 O during the inspiratory phase and a value of +100 cm H 2 O during Valsalva manoeuvre [8].

226 Emerg Radiol (2012) 19:225 235 Some studies have shown that these pressure values can increase up to about +1000 cm H 2 O at the time of trauma [7, 8]. This pressure gradient could also be responsible for organ injury in acute stage since intrathoracic herniation of abdominal organs can occur in a widely variable interval of time. The trauma force vector may be frontal or lateral. The first case is the most frequent (about 3:1) and consists of a sudden deformation of the rib cage which may lead to diaphragm muscle tearing. Frontal impacts represent the main cause for the abrupt change in intra-abdominal pressure gradient, resulting in large diaphragmatic rupture [4, 8, 9]. Lateral impacts may cause detachment of the peripheral tendinous insertions of the diaphragm from the ribs (avulsion) and rib fractures. Usually, diaphragmatic injuries resulting from blunt trauma are of considerable size (about 10 15 cm) and radial morphology, while injuries related to penetrating trauma are smaller (about 1 4 cm, less than 2 cm in 85% of cases) [10]. Blunt diaphragmatic injuries occur more frequently on the left side of the diaphragm (56 86% of cases); right hemidiaphragm ruptures represent 11 39% of the cases, while bilateral tears are extremely rare [1 6]. Different causes are identified as primarily responsible for left hemidiaphragm injury including: (a) congenital area of structural weakness along the embryonic fusion point of the lumbar and costal diaphragm component or lumbar triangle, (b) the presence of the oesophageal hiatus, which contributes to weaken the left side, (c) the protective effect exercised by the liver on the right hemithorax, acting as a sort of cushion that dampens the transmission of the high intra-abdominal pressure generated by the trauma, and (d) greater difficulty in correct identification of right hemidiaphragm traumatic lesions, which therefore remain partly unknown [8, 9, 11]. Normal anatomy, types of tears and weakness areas are shown in the Scheme 1. Scheme 1 Anatomy of the diaphragm, types of tears and weakness areas. ICV Inferior vena cava, ES esophagus, A aorta, RC right crus, LC left crus, tt transverse tear, rt radial tear, pd peripheral detachment. The pink area corresponds to the central tendon. The yellow areas indicate the two sites of congenital weakness most frequently involved in blunt trauma. a Lumbar triangle, and b region of oesophageal hiatus Associated injuries The diaphragm location and its anatomical close proximity with the thoracic and intra-abdominal organs explain the reason for the high percentage of associated injuries, which occur in 52 100% of trauma patients [3, 9, 12, 13]. Hemothorax, pneumothorax, multiple rib fractures are appreciable in 90% of patients with diaphragmatic rupture due to blunt trauma [2, 5, 9, 12]. Meyers et al. indicate a 5% incidence of thoracic aorta trauma in a group of 68 patients with diaphragmatic injury [1]. Other frequent related lesions affect the spleen (27 60% of cases) and the liver in 93% of right hemithorax trauma and in 24% of left hemithorax trauma patients [9 15]. Other common related injuries are pelvic fractures (40 55%), while long bone fractures (45 85%) and head trauma (25 55%) are common in nonthoracoabdominal sites [1, 5, 9]. Some authors highlighted that patients with blunt diaphragmatic rupture have a very high injury severity score (ISS) and a higher chest, abdomen, pelvis and extremity abbreviated injury scale (AIS) score than all blunt trauma patients, in general [12]; these data indicate the need to always suspect and look closely to blunt diaphragmatic injury in the presence of associated injuries, whether encephalic, thoracic or abdominal. Natural history The natural history of diaphragmatic injuries can be divided into three main stages. The acute phase is the period immediately following the traumatic event, when symptoms may be absent or obscured by potentially associated lesions [3, 12, 13]. In case of undiagnosed injury and/or not repairing diaphragmatic lesion, the so-called latent phase may occur. In this stage, which ranges from a few days to tens of years, patients may complain of nonspecific and heterogeneous symptoms such as dyspnea, abdominal cramps, dyspepsia and vomiting. On physical examination, although decreased physiological breath sounds represent the most frequent finding, auscultation of abnormal bowel sounds in the chest is due to the intrathoracic presence of gastrointestinal segments [13 15] and represents a clinical sign of a diaphragmatic hernia. Usually, the latent stage is diagnosed using clinical and instrumental examinations performed for other purposes, often after several years of injury. The obstructive phase is represented by the dramatic evolution of the latent stage of disease. It is generally characterized by a massive diaphragmatic herniation of the abdominal organs into the thoracic cavity with mediastinum shift and cardiorespiratory impairment; this event may be possibly associated with ischemia and/or perforation of the herniated organs. The clinical evolution is

Emerg Radiol (2012) 19:225 235 227 associated to a significant increase in morbidity (30 80% of cases) [6, 16 18]. Imaging Chest radiograph Chest radiography is still the first technique performed in the primary survey of the polytraumatized patient [9 11]. However, the need for a proper staging of the decelerated trauma requires the use of multidetector CT (MDCT) in stable and semistable subjects. The preliminary chest radiograph is normal or nonspecific in about 20 50% of patients with traumatic rupture of the diaphragm. This is due to the large range (7 66%) of initially unrecognized injuries [9, 11]. The literature indicates that chest radiographs performed at patient admission is diagnostic or reveals a suspicion of left hemidiaphragmatic injury in 27 68% of cases, resulting in diagnosis or suspicion of right hemidiaphragmatic injury in 17 33% [2, 9, 19]. Two main radiographic signs of diaphragmatic rupture have been described: herniation of visceral organs into the thoracic cavity, with or without focal constriction of the herniated mass at the herniation site, known as collar sign [2, 4, 5, 9], and identification of a nasogastric tube apex in the supradiaphragmatic position [2, 11]. Elevation of the hemidiaphragm represents an additional nonspecific sign with a 61% accuracy (Fig. 1). Although the positive predictive value of this sign has been evaluated [2, 4, 5], its real diagnostic value is limited, since it may result from muscle rupture and tendon avulsion, or even be the expression of pleural effusion, post-traumatic paralysis of the phrenic nerve or diaphragmatic eventration. Other signs of diaphragmatic rupture include obliteration of costophrenic sulcus, distorted or blurred diaphragmatic profile and air fluid levels in the lower chest. Although these sign are considered helpful for TDR diagnosis, they are more often found in other pathological conditions (pleural effusion, hydropneumothorax, atelectasis, pneumonia, lung contusions, pneumatocele, etc.); for this reason, clinical features and diagnostic integration are mandatory [2, 5, 11]. Chest radiography retains its diagnostic value in the follow-up checks that can suggest the possibility of diaphragmatic injury on the basis of radiographic changes [2, 8, 9]. Abolition of assisted ventilation may facilitate the diagnosis of lesions of the diaphragm too, as it allows the establishment of a thoracoabdominal pressure gradient that could lead to progressive intrathoracic herniation of abdominal viscera [11, 20]. Computed tomography CT represents the imaging method of choice for the correct classification of the trauma patient, beyond the presence of radiographic and clinical findings of diaphragmatic rupture. Studies based on the use of single-layer CT values reported high specificity (76 99%), but lower sensitivity (14 61%) in the diagnosis of diaphragmatic disruption [9, 19, 21, 22]. This is attributed to the use of scans with large collimation (8 10 mm) that does not allow proper visualization of the diaphragm dome and the adjacent structures, with poor quality of multiplanar reformations (MPR). The recent literature has highlighted the improvement of diagnostic sensitivity (61 100%) due to the assistance of Fig. 1 A 53-year-old patient who sustained a motor vehicle collision. At admission, supine chest radiograph shows elevation of the left hemidiaphragm and air fluid level suggestive of gastric fundus herniation in the thoracic cavity. Rib fractures, pulmonary subatelectasis and mediastinal displacement are also evident Fig. 2 Discontinuity of diaphragmatic profile. A 72-year-old man who sustained a fall from a tree 2 years before, suffering from intense dyspnea (latent clinical phase). Coronal maximum intensity projection (MIP) reformation shows loss of continuity of the left hemidiaphragmatic contour (arrow) with intrathoracic herniation of the splenic flexure and homentum

228 Emerg Radiol (2012) 19:225 235 modern CT equipment (spiral CT scanners and the latest multilayer CT) with high spatial resolution, high speed, reduction of artifacts and the ability to get high quality MPR on sagittal and coronal planes [5, 9 11, 18, 23 29]. A retrospective review of the single-layer spiral CT of 41 patients was performed by Keellen et al. showing a sensitivity of 78% and 50% for left- and right-sided diaphragmatic injuries, respectively, with an overall specificity of 100% for both sides [24]. Bergin et al. found a spiral CT overall sensitivity of 90%, with 100% and 75% specificity for left and right-sided rupture, respectively. Subsequently, Larici et al. [25] evaluated the value of MPR sagittal and coronal reformations and calculated an overall spiral CT sensitivity of 84% [25]. Lastly, in the more recent studies of Nchimi et al. and Dessert et al., CT analysis of the various diaphragmatic rupture signs allowed to detect a sensitivity of this technique that ranges between 77% and 100% [26 28]. These data show that diagnostic accuracy is improved by the enhancement of CT equipment. The protocol of CT study varies depending on CT scanner available and patient s clinical conditions. Today, patients with thoracoabdominal trauma should undergo the whole body MDCT for trauma protocol [30, 31]. This protocol allows scanning of large volumes in a single acquisition, obtaining the data in a few seconds. Specifically, is advisable to use high-flow medium contrast injection and thin collimation in order to obtain optimal representation of head to toe lesions, including small diaphragm tears and potentially life-threatening vascular lesions. There is common agreement that the MDCT assessment should be reserved for hemodynamically stable and semi-stable patients [31, 32]. CT signs of diaphragmatic rupture are classified as direct and indirect and associated CT signs. Fig. 3 Intrathoracic herniation of abdominal viscera. Patient presenting with slight dyspnea and abdominal pain after a motorcycle collision occurred many years before. Chest radiograph (a) shows poorly defined left lower hemitorax without clear visualization of left hemidiaphragm. Axial noncontiguous images at the lower thorax (b,c) show abdominal viscera in the thoracic cavity. Oblique sagittal MPR reformation (d) demonstrates intrathoracic herniation of the upper left colon and the adjacent fat tissue through a large diaphragmatic tear

Emerg Radiol (2012) 19:225 235 229 Direct signs Discontinuity of diaphragmatic profile This sign is associated with a sensitivity of 58 80% and a specificity of 83 95% [21, 23 25, 33 36]. It consists of the direct evidence of the tear of the musculotendinous component, often thickened by post-traumatic oedema (Fig. 2). This finding, already visualized in the axial planes, is more frequently detected in the sagittal images [23, 24]. A related CT sign is the segmental nonrecognition of diaphragm. This sign shows a sensitivity of 86%, a limited specificity (68%) and can be falsely positive in the presence of associated intra or retroperitoneal hematoma, pulmonary contusion and atelectasis of basal lung segments [9, 24, 26]. Furthermore, some studies have reported that diaphragmatic defects can be found in 6 11% of the healthy population with an incidence increasing proportionally with age [34]. Intrathoracic visceral herniation It represents a frequently reported sign, with values of sensitivity and specificity of 60 90% and 94 100% respectively [9, 23 31]. It is due to the sharp increase of intra-abdominal pressure at the time of the trauma or to the thoracoabdominal pressure gradient that develops in the subacute phase, which induces the progressive enlarging of the diaphragmatic tear. In case of left hemidiaphragmatic injury, stomach, colon, small bowel, kidney and retroperitoneal fatty tissue are the organs that most frequently herniate into the chest cavity (Figs. 2 and 3) [24]. Herniation of right colic flexure, small bowel and gallbladder can occur as a result of right-side injury. Intrapericardial herniation of abdominal viscera is a rare occurrence and could lead to cardiac tamponade [9]. These findings should not be mistaken with congenital or iatrogenic diaphragmatic herniation (Bochdalek and Morgagni hernias). Collar sign It is a waistlike constriction of the herniated abdominal organs at the site of diaphragm tear produced by diaphragmatic compression (Fig. 4). The observed sensitivity is variable depending on the side involved in trauma (36 85% and 17 50% for left-sided and right-sided injury respectively), with an overall specificity ranging from 80 to 100% [9, 23 27]. The collar sign is typically produced by the stomach on the left and the liver on the right side. Although axial CT images may demonstrate the collar sign, this finding can be easily revealed by MPR images. However, both axial and MPR allow clear detection of possible signs of visceral ischemia of the herniated organs (Fig. 5). Hump sign and Band sign Usually described as two variants of the collar sign, they specifically refer to rightsided diaphragm injuries and can be more easily identified using high quality sagittal and coronal reformations [9, 27]. Fig. 4 Collar sign. A 53-year-old patient who suffered from a blunt abdominal trauma in a motor vehicle collision (same case of Fig. 1). Although the axial image (a) is already diagnostic, sagittal MPR reformation (b) shows herniation of the stomach across the left hemidiaphragm with abrupt narrowing at the level of the diaphragmatic tear (arrows). Note also the dependent viscera sign. Pleural effusion and lung base atelectasis are associated injuries The hump sign (sensitivity of 83%) describes a portion of liver herniating through the site of diaphragm tear and forming a hump-shaped mass (Fig. 6). The band sign (sensitivity of 33%) is a linear low density portion on liver dome, at the level of herniation into the chest cavity. Rees et al. believe that it represents under-perfusion of liver parenchyma due to the compressive edge of the torn diaphragm and relative diminished enhancement compared with the adjacent normally perfused liver (Fig. 6) [27]. Dependent viscera sign In healthy individuals in supine position, the diaphragm supports the abdominal organs preventing them coming in contact with the posterior chest wall. The dependent viscera sign (sensitivity 52 90%; specificity 71 96) appears on the right side if the upper third of the liver keeps in contact with the posterior ribs and on the

230 Emerg Radiol (2012) 19:225 235 Fig. 5 A 22-year-old man presenting with severe fever, dyspnea and vomiting who sustained a blunt thoracic trauma after a motor vehicle collision 1 month before (obstructive phase of blunt diaphragmatic injury). Supine chest radiograph (a) shows a large air fluid level in the lower left thorax (arrow), pulmonary atelectasis and pleural effusion. Axial TC scan (b) demonstrates herniation of the stomach into the lower thoracic cavity associated with decreased enhancement of the gastric walls and pneumatosis (arrow); extensive reactive pleural effusion, pulmonary atelectasis and partial mediastinal displacement are also evident. Coronal reformation (c) shows poor enhancement of the herniated gastric fundus (arrow)in comparisonwiththe normal enhancement of the subphrenic portion of the gastric body (arrow head). Additional axial CT scan (d) after administration of water-soluble oral contrast medium (d) demonstrates a collection of contrast medium in the pleural cavity due to gastric perforation (arrow). Source: Courtesy of Prof. G. Gualdi and Dr. E. Casciani, Radiology DEA Department, Umberto I Hospital Sapienza University, Rome, Italy left side if the stomach, bowel or spleen lie against the posterior chest wall (Figs. 4 and 7) [24]. This sign, found bilaterally and usually associated with a wide diaphragm tear, is more frequently generated by ruptures of classic point of structural weakness of the diaphragm, represented by the left postero-lateral area. In any case, the abdominal contents herniated into the chest cavity obliterate the posterior costo-phrenic sulcus [24, 25, 35]. This sign may be obscured bilaterally, more often on the right side, because of the presence of hemothorax and/or hemoperitoneum [24]. Some pathological conditions, such as congenital hernias or diaphragmatic eventration, may simulate the dependent viscera sign, leading to the incorrect diagnosis of posttraumatic diaphragm rupture (Fig. 8) [24]. Thickening of the diaphragm Diaphragmatic rupture is sometimes related to the thickening of its peripheral portions, especially near the tendinous insertions, due to its retraction and hemorrhagic infarction (Fig. 8). This sign shows a sensitivity of 36 60% and a specificity of 58 77% [25, 26] and can be falsely positive in cases of associated intra-or retroperitoneal hematoma [26]. Some authors have described the thick crus sign which describes an abnormally thickening of diaphragmatic crus in trauma patients [37] (Fig. 9). Conversely, other studies suggest that this aspect can exist even in healthy subjects, being variable based on the age of the patient [24, 34]. Dangling sign This sign has been recently described and is visible when the free edge of the torn diaphragm curls inward toward the abdominal cavity away from the thoracoabdominal wall, having the appearance of a commashaped fragment of diaphragm (Fig. 10). The reported sensitivity and specificity are 54% and 98% respectively

Emerg Radiol (2012) 19:225 235 231 Fig. 6 Hump sign and band sign. A 47-year-old man who sustained a blunt thoracoabdominal trauma after a motor vehicle collision 5 years before. Chest radiograph (a,b) shows elevation of the apparent right hemidiaphragm. Axial CT (c) shows a double liver dome with a low attenuation band inbetween (arrow). This effect is due to axial slice crossing the herniated haepatic portion and subdiaphragmatic one. Haepatic parenchyma shows a sort of indentation representing the liver compression by the edge of the diaphragm (arrows). Coronal (d) and sagittal (e) MPR reformations clearly show a hump-shaped mass formed by the right liver dome herniating through the diaphragm (stars) [28]. Finally, Nchimi et al. [26] have described a case of hypoattenuatxed hemidiaphragm compared to the opposite side, as a result from post-traumatic devascularization. MDCT imaging has improved the overall sensitivity and specificity of the method in recognizing diaphragm traumatic rupture. Nevertheless, the diagnostic improvement achieved for left-sided injuries (sensitivity ranging from 78% to 100%) did not have the same results for the right side (sensitivity of 50 79%) [23 29]. The main reason is probably the hemidiaphragmatic location close to the liver, which is often poorly distinguishable, having similar densitometric coefficients. Moreover, since the dome of the right haepatic lobe is the structure most frequently herniating, the evidence of many CT signs of right-side ruptures requires the presence of both a large defect in the diaphragm and concomitant injuries of the ligaments that support the liver [9, 26]. For left-sided diaphragm injuries, the abovementioned signs are quite similar for

232 Emerg Radiol (2012) 19:225 235 Fig. 7 Dependent viscera sign. Two distinct cases. a A 62-year-old woman who sustained a blunt thoracoabdominal trauma after a fall from a bicycle 3 years before. Avulsion of the right hemidiaphragm with intrathoracic herniation of the liver, gallbladder and right colic flexure. In the supine position, the liver and the abdominal fat lie against the posterior thoracic wall, obliterating the costophrenic sulcus (arrow). b A 38-year-old man who sustained a motorcycle collision. Left hemidiaphragmatic rupture with intrathoracic herniation of the stomach obliterating the left costo-phrenic sulcus (arrow). Note also the waistlike constriction of the stomach (collar sign), suggesting its herniation through the injured diaphragm (arrow head) several reasons: the easy herniation of abdominal contents and fat through left hemithorax due to negative intra-pleural pressure and the close proximity to intra and retroperitoneal fat [9]. Fig. 8 Diaphragmatic eventration. A 22-year-old patient who sustained a motor vehicle collision, with possible diaphragmatic injury. The axial scan (a) shows intestinal loops, abdominal fat and part of the stomach at the level of the lower thoracic cavity; furthermore, the spleen lies in the dependent position (dependent viscera sign) and obliterates the left costophrenic sulcus. However, coronal MPR reformation shows integrity of the diaphragmatic profile (arrows), thus eliminating any doubt of diaphragmatic injury Fig. 9 Diaphragm thickening. A 32-year-old man who sustained a motorcycle collision. Axial CT scan (a) shows discontinuity of left hemidiaphragm (arrows) with thickening of diaphragmatic crus due to its retraction and hemorrhagic infarction (asterisk). MPR coronal reformation (b) offers a better spatial representation of the injured diaphragmatic crus, which is thickened and retracted (arrow). Furthermore, a splenic contusion of the lower splenic pole and subcutaneous enphysema are also visible

Emerg Radiol (2012) 19:225 235 233 Magnetic resonance Routine use of cardiac and respiratory gating, the possibility of direct acquisition in coronal and sagittal plane and high contrast resolution make potentially useful to assess diaphragm injury (Fig. 11). T1-weighted and gradient-echo sequences display the diaphragm as a continuous hypointense band. Intra-abdominal Fig. 10 Dangling sign in right (a) and left (b) hemidiaphragmatic rupture. Two distinct cases of blunt abdominal trauma after car accidents. The free edge of the torn diaphragm curls inward (arrows) away from chest wall Indirect and associated CT signs Elevated hemidiaphragm and active peridiaphragmatic bleeding are the most significant indirect signs of diaphragmatic injury. In a preliminary CT scout view, the elevation of hemidiaphragm is often the first predictor of diaphragmatic injury and the value of this finding has already been discussed previously. Active peridiaphragmatic bleeding is suggestive of laceration but associated with low specificity. Although sometimes described as the only sign of suspected diaphragmatic injury [25], contrast medium extravasation in close proximity to the diaphragm may be related to associated injuries (parenchymatous organs, gastrointestinal viscera, intercostal arteries, etc.) [25, 26]. Further signs frequently associated include rib fractures, hemothorax, pleural effusion, pulmonary atelectasis, hemoperitoneum and parenchymal organ injuries (liver, spleen, pancreas, kidneys, adrenal glands) that, while leading to the suspicion of traumatic diaphragm, might obscure the direct TC signs previously described. As described above, blunt diaphragmatic rupture is associated with high ISS and AIS score [12]; if associated injuries are present, a thorough search of diaphragm is suggested, especially if the injuries are present on both sides. Fig. 11 Patient with right emidiaphragmatic rupture and avulsion who sustained blunt thoracoabdominal trauma after a fall from the bicycle 3 years before (same case of Fig. 7a). T1-weighted MR axial image (a) shows abrupt interruption of the diaphragmatic profile at the left costal posterolateral site (arrows). T2-weighted coronal images (b,c) show intrathoracic herniation of liver dome through a diaphragmatic tear with collar sign (arrows) and herniation of haepatic flexure and gallbladder (arrow heads)

234 Emerg Radiol (2012) 19:225 235 and mediastinal fatty tissue are hyperintense in these sequences and therefore easily distinguishable from the diaphragmatic profile; the same applies to abdominal organs, characterized by relative hyperintensity. Some authors suggest that the T1- weighted sequences are to be preferred [9, 18, 38]. The use of intravenous gadolinium, the ability to suppress the signal from fatty tissue and additional sequences where needed improve the diagnostic accuracy [4, 9]. Nevertheless the ability of thin collimation and high quality of volumetric reformations of current MDCT scanners has significantly reduced the necessity of using magnetic resonance imaging in clinical practice, both for acute and long-term settings. Further imaging studies Water-soluble medium contrast and oral barium administration have been described to be able to identify traumatic injuries of the diaphragm. Allen et al. [39] suggest that the opacification of gastro-intestinal tract using oral medium of contrast does not increase the diagnostic sensitivity of CT. Other studies established that the US can detect the site of traumatic diaphragm injury, floating diaphragm edges, visceral herniation and some indirect signs of diaphragmatic rupture [40]. The diagnostic value of these techniques is confined to the theoretical possibilities of modern imaging, with limited application in the clinical practice [29, 40]. Indications for surgical management Timely diagnosis and correct identification of diaphragmatic injury and any associated lesions are essential for proper clinical management and surgical treatment. When the diagnosis of diaphragmatic rupture is performed, surgical approach is recommended as soon as possible in order to limit the expansion of the traumatic tear, to prevent or reduce herniation of intra-thoracic abdominal viscera and to avoid late complications such as respiratory distress and possible strangulation of the herniated viscera, both associated with high mortality rates. Surgical approach to diaphragmatic ruptures includes: open surgery such as laparotomy and thoracotomy, or less invasive methods represented by laparoscopy or thoracoscopy; the decision depends critically on associated lesions and the preference of surgeons. High incidence of intraabdominal organ injury dictates a trans-abdominal approach with a midline laparotomy because it offers the opportunity to repair diaphragmatic tears and associated lesions in the same time [12, 41].Thisincisioncanbeextendedtoa thoracolaparotomy if significant intrathoracic injuries are correctly diagnosed. The discussion about the utility of laparoscopic or thoracoscopic repair in acute and chronic TDR is still controversial. Some authors recommend the use of minimally invasive methods in left chronic diaphragmatic lesions and in hemodynamically stable patients with penetrating left thoracoabdominal trauma [41, 42]. Finally, some reports support the role of video-assisted thoracoscopic surgery for stable patients when intraabdominal and controlateral diaphragmatic injuries are excluded [43]. In some cases of high hemodynamic instability related to seriously bleeding injuries, it is suggested to even postpone surgical diaphragmatic repair; actually, diaphragmatic injury is not to be considered a true emergency sensu stricto if there are not associated complications such as bleeding injuries in its context, ischemic changes of the herniated abdominal viscera or significant compressive lung atelectasis [12, 22, 41 44]. Conclusions Despite the significant improvement in diagnostic accuracy values of MDCT imaging and the possibility of spatial diaphragm representation with the current postprocessing techniques, traumatic injuries of diaphragm remain a diagnostic challenge in the assessment of polytraumatized patients. The natural history has not substantially changed in recent years and is combined with a highly variable and still high rate of missed diagnosis, due to the anatomical position of diaphragm and the complex pathophysiological implications related to the rupture, which is not always complete and associated with herniation of abdominal viscera through diaphragm. Radiologists should keep the possibility of diaphragmatic injuries in mind in multitrauma patients and should routinely integrate the axial images CT with MPR reformations in order to detect any potential, subtle or doubtful sign of diaphragmatic injury. References 1. 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