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Whole-body STIR MR imaging in suspected child abuse: An alternative to skeletal survey radiography?
European Journal of Radiology Extra 63 (2007) 43–47
Whole-body STIR MR imaging in suspected child abuse: An alternative to skeletal survey radiography? Enno Stranzinger a , Christian Johannes Kellenberger a,∗ , Sabine Braunschweig b , Rachel Hopper c , Thierry Andr´e Gerard Marie Huisman a a
Department of Diagnostic Imaging, University Children’s Hospital Z¨urich, Steinwiesstr. 72, CH-8032 Z¨urich, Switzerland b Department of Paediatrics, University Children’s Hospital Z¨ urich, Steinwiesstr. 72, CH-8032 Z¨urich, Switzerland c University of Michigan Medical School, Ann Arbor, USA Received 26 January 2007; accepted 2 April 2007
Abstract Child abuse is a major problem worldwide. An early and reliable recognition and diagnostic work up is important for the management of these children and their caregivers. Radiological skeletal surveys in combination with brain imaging are mandatory in the initial evaluation. In selected cases, repeat radiography and/or bone scintigraphy is necessary. The radiation dose from these studies is significant. Whole-body STIR MR imaging permits evaluation of the entire skeleton and all viscera with a single examination while avoiding ionizing radiation. We report on a 2-month-old female suspected victim of child abuse in whom whole-body STIR MR imaging revealed multiple rib fractures suggestive of child abuse that were only partially recognised by conventional radiography. Our case suggests that whole-body STIR MR imaging should be considered as an alternative imaging modality in children in whom child abuse is suspected. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: MRI; Whole-body imaging; Trauma
1. Introduction The World Health Organization (WHO) recognises child abuse as a major problem worldwide. Although data are difficult to acquire, the WHO estimates that worldwide 40 million children aged 0–14 years are abused or neglected [1]. Early and reliable recognition of child abuse is mandatory and accurate imaging is essential in making the diagnosis [2–4]. However, false positive imaging studies are troublesome as they may have immense unwanted social, psychological, medical and legal consequences for the child and caregivers. On the other hand, false negative studies may result in continuation of child abuse which may impact the child’s future physical and psychological health. ∗ Corresponding author at: Department of Diagnostic Imaging, University Children’s Hospital Z¨urich, Steinwiesstrrasse 75, CH-8032 Z¨urich, Switzerland. Tel.: +41 44 2667500; fax: +41 44 2667158. E-mail address: [email protected] (C.J. Kellenberger).
1571-4675/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2007.04.001
Depending on the age of the child different patterns of injury may be observed. Very young children commonly present with “shaken baby syndrome”, a well-defined constellation of injuries that includes severe shearing injuries of the brain and hypoxia, damage to the spinal cord and neck, and fractures of the ribs. In older children, other fractures are more frequent [2]. Unusual radiological findings, especially traumatic lesions that do not match the clinical and/or trauma history, multiple fractures of different ages and fractures in unusual locations should alert the radiologist. Specific lesions such as posterior rib fractures, metaphyseal lesions, scapular fractures, spinous process fractures and sternal fractures are especially suggestive of child abuse [2,5]. A complete radiological skeletal survey is a wellestablished imaging modality in the diagnostic work up of children suspected for non-accidental trauma [2–4]. Computed tomography (CT) and magnetic resonance (MR) imaging are added if traumatic brain injury is suspected. Repeat radiographs or bone scintigraphy may be considered in those cases where non-accidental trauma is strongly
44
E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47
suspected but initial imaging is negative [3,4]. It is well known that acute fractures may not be apparent or may be overlooked on early radiographs. The radiation dose of repeat radiographs and/or bone scintigraphy is significant [6]. Therefore, alternative imaging modalities devoid of ionizing radiation are necessary in these young patients. Wholebody imaging with short tau inversion recovery (STIR) MR sequences has proven its value as a survey imaging technique for various non-traumatic indications [7–10]. Here we report on a 2-month-old female suspected victim of child abuse in whom multiple acute posterior and lateral rib fractures were identified by whole-body STIR MR imaging.
2. Case report A 2-month-old girl was presented to the emergency department of our children’s hospital because of a recent increase in “fussiness and crying”, most noticeably at night. Symptoms reportedly started 2 weeks prior to presentation. The girl was born at 34 weeks of gestation, and the postnatal period was unremarkable. On physical examination, one haematoma was seen on the forehead (4 cm × 2 cm); a second was seen on the left cheek (1 cm × 1 cm). There were no petechiae or ecchymoses and the child otherwise appeared well. Vitamin K had been administered appropriately. Family history was unremarkable for hereditary coagulopathies. According to the mother, there was no history of trauma and the patient had remained exclusively in her parents’ care. Cranial CT revealed a subacute, focal subarachnoid haemorrhage within the right sylvian fissure (Fig. 1). No additional posttraumatic intracranial lesions were observed. The overlying skull was intact and no shearing injuries were seen. Chest/abdomen radiography showed focal widening of the lateral 6th to 8th ribs on the left and possibly of the posterior 9th rib on the right. In addition, discrete pleural thickening or effusion was seen on the left (Fig. 2). The multifocality of the chest lesions, the unusual intracranial finding and the discrepancy between the cranial CT findings and clinical symptoms as well as the facial haematomas raised the suspicion of child abuse and prompted an MR examination of the brain. Whole-body STIR imaging was added in order to detect additional skeletal or soft tissue injuries that would support the diagnosis of non-accidental trauma. MR imaging was performed on a 1.5 Tesla MR unit (General Electric Medical Systems, Milwaukee, Wisconsin, USA). The girl was examined under sedation with propofol. Brain imaging was performed according to the routine departmental trauma protocol. For the whole-body imaging, we used an eightchannel cardiac phased array surface coil. Three overlapping STIR sequences were acquired in the coronal plane covering the girl from the vertex to the feet. Imaging parameters were derived from previously published whole-body STIR imaging protocols [10]. MR imaging of the brain confirmed the CT findings. The signal characteristics (T1-hyperintense, T2- and T2*-
Fig. 1. Axial CT of the brain shows hyperdense subarachnoid haematoma within the right sylvian fissure. No additional lesions, no midline shift, no skull fracture.
hypointense) indicated that the subarachnoid haemorrhage was 1–2 weeks old. No additional posttraumatic intracranial lesions were seen. In addition, lesions that could have explained a spontaneous haemorrhage (e.g. an aneurysm, vascular malformation or tumour) were excluded. Whole-body STIR imaging revealed more extensive lesions of the chest wall than did radiography (Fig. 3). Not only did it confirm the previously identified lesions of the lateral 6th to 8th ribs on the left, but also showed hyperintense signal within the marrow space and in the surrounding soft tissue of multiple posterior ribs bilaterally. The posterior 10th rib on the right showed an irregularly thickened hypointense contour and also hyperintense signal in the adjacent soft tissue. In addition, the bone marrow signal of the left distal radial and ulnar metaphyses was slightly increased. The remainder of the skeleton, soft tissues and parenchymal organs showed normal signal. Selected follow-up radiographs were performed 2 weeks later. The chest radiograph confirmed the rib fractures by showing callus formation along the lateral 6th to 8th rib on the left (Fig. 4) and along the posterior ribs bilaterally. The radiograph of the forearm was unremarkable.
3. Discussion Child abuse or non-accidental trauma is frequently unrecognised, misrecognised or under recognised. The shortand long-term outcomes and physical and psychological sequelae may be devastating for the child and their sib-
E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47
Fig. 2. Frontal chest/abdomen radiograph shows widening of the left lateral 6th to 8th ribs with adjacent pleural thickening and possible focal thickening of the right posterior 9th rib suggesting multiple rib fractures.
45
lings. An early and reliable diagnosis is a sine qua non [2–5]. Skeletal surveys encompassing multiple conventional radiographs and a brain CT as well as possible follow-up radiographs or additional bone scintigraphy represent a significant radiation dose to the child. A skeletal survey with 16 films using computed radiography has about 0.16 mSv of radiation [4]. The effective dose equivalent for a bone scan is about 0.11 mSv/MBq in newborns, 0.042 mSv/MBq for 1-year-old infants and 0.021 mSv/MBq for 5-year-old children [6]. Skeletal radiographs may overlook subtle acute osseous lesions. Fractures near the growth plates, the classic metaphyseal lesions, may be difficult to detect on bone scintigraphy because of the high degree of tracer uptake of the normal growth plate [4]. In addition, soft tissue lesions, with the exception of calcified haematomas, are seldom radiographically visible [4]. Consequently, an alternative imaging modality should be considered that preferably does not use ionizing radiation, is widely available, images the entire child, and allows visualisation of both the bone and soft tissues. Whole-body STIR MR imaging fulfils most of these requirements. Several studies have shown the value of wholebody STIR MR imaging in adults for detecting metastatic bone disease, staging of breast carcinoma and for assessment of multifocal diseases such as polymyositis [7–9]. In a series of 140 children, whole-body STIR MR imaging has been shown to be a sensitive radiation-free screening technique for assessing skeletal, bone marrow and soft tissue disease in a reasonable time [10]. Several researchers have suggested that whole-body STIR MR imaging may have a role in the assessment of child abuse [8,9]. In this setting, one single non-ionizing imaging modality could be used to assess for brain, visceral and skeletal injuries [9,10]. To the best of our knowledge, this is the first report on the use of whole-body STIR MR imaging in child abuse and its findings. Our case shows that the whole-body STIR technique can easily identify fractures by the hyperintense signal in the bone marrow and adjacent soft tissue. Lesion conspicuity is high because of the contrast between the hyperintense
Fig. 3. Selected coronal STIR images show hyperintense signal in the bone marrow of lateral ribs on the left, of posterior ribs bilaterally and increased signal in the surrounding soft tissue. The 10th rib on the right shows an irregular hypointense contour. Arrows indicate respective ribs.
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E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47
Fig. 4. Comparison (a) initial chest radiograph; (b) coronal STIR image; (c) follow-up chest radiograph. Callus formation confirms rib fracture.
traumatic lesion and the relatively low signal of normal tissues, which is inherent to the STIR sequence. Oedematous or proton-rich tissues have prolonged T1 relaxation and T2 decay times, resulting in high signal intensities on STIR imaging, whereas the signal from fat is suppressed by an initial 180◦ inverting pulse which nulls the longitudinal magnetization of fat at the time of the 90◦ excitation pulse [10]. In our case, STIR MR imaging was more sensitive than radiography. The STIR images revealed a more extensive chest wall injury with more rib fractures than seen on the initial radiograph, which were eventually confirmed on the follow-up radiograph. Further, STIR images revealed increased signal in the left distal radial and ulnar metaphyses suggesting fractures, which however were not confirmed by follow-up radiography. Although this could be a false positive MR finding, the STIR technique might have shown minor bone bruises which only resulted in minimal reparative processes not depicted on the follow-up radiographs. The true sensitivity and specificity of STIR MR imaging for detecting the different kinds of fractures encountered in non-accidental trauma need to be studied in larger prospective studies. Whole-body STIR MR imaging has several limitations. Although overt parenchymal lesions of the brain, lungs, liver, spleen, and kidneys can readily be detected, smaller parenchymal lesions may be missed due to the relatively low spatial resolution. Currently, whole-body STIR MR imaging cannot replace dedicated brain MR to exclude intracranial lesions, but can easily be added to brain MR examinations. The STIR technique is not specific for traumatic lesions because any inflammatory, infectious or neoplastic lesion with increased water content or protein concentration shows high signal. Therefore, the MR findings need to be interpreted in context with the clinical setting and other imaging results. Infants and small children require sedation for an MR study.
Finally, critically injured children are not easily accessible within the bore of the magnet, which can be troublesome in the emergency setting. In conclusion, whole-body STIR MR imaging is a radiation-free technique covering the entire body that is sensitive for traumatic lesions suggestive of child abuse, such as lateral and posterior rib fractures. The high lesion conspicuity allows depiction of radiographically occult bone and soft tissue lesions in an early phase. Currently, whole-body STIR MR imaging cannot replace a skeletal survey, but should be considered as alternative imaging technique in cases where follow-up radiographs or bone scintigraphy are indicated. This will reduce radiation exposure to small children significantly. Prospective studies are required to determine the value of whole-body STIR MR imaging in the diagnostic work up of children suspected of non-accidental trauma.
References [1] WHO recognises child abuse as a major problem. The Lancet 1999;353(9161):1340. [2] Kleinman PK. Diagnostic imaging of child abuse. Baltimore: Williams & Wilkins; 1987. [3] Kleinman PK, Nimkin K, Spevak MR, et al. Follow-up skeletal surveys in suspected child abuse. AJR Am J Roentgenol 1996;167(4):893–6. [4] Mandelstam SA, Cook D, Fitzgerald M, Ditchfield MR. Complementary use of radiological skeletal survey and bone scintigraphy in detection of bony injuries in suspected child abuse. Arch Dis Child 2003;88(5):387–90. [5] Bulloch B, Schubert CJ, Brophy PD, Johnson N, Reed MH, Shapiro RA. Cause and clinical characteristics of rib fractures in infants. Pediatrics 2000;105(4):E48. [6] Hahn K, Fischer S, Colarinha P, et al. Guidelines for bone scintigraphy in children. Eur J Nucl Med 2001;28(3):42–7.
E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47 [7] Eustace S, Tello R, DeCarvalho V, et al. A comparison of whole-body turbo STIR MR imaging and planar 99mTc-methylene diphosphonate scintigraphy in the examination of patients with suspected skeletal metastases. AJR Am J Roentgenol 1997;169(6):1655–61. [8] O’Connell MJ, Powell T, Brennan D, Lynch T, McCarthy CJ, Eustace SJ. Whole-body MR imaging in the diagnosis of polymyositis. AJR Am J Roentgenol 2002;179(4):967–71.
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[9] Hargaden G, O’Connell M, Kavanagh E, Powell T, Ward R, Eustace S. Current concepts in whole-body imaging using turbo short tau inversion recovery MR imaging. AJR Am J Roentgenol 2003;180(1):247– 52. [10] Kellenberger CJ, Epelman M, Miller SF, Babyn PS. Fast STIR whole-body MR imaging in children. Radiographics 2004;24(5):1317– 30.
Whole-body STIR MR imaging in suspected child abuse: An alternative to skeletal survey radiography? Enno Stranzinger a , Christian Johannes Kellenberger a,∗ , Sabine Braunschweig b , Rachel Hopper c , Thierry Andr´e Gerard Marie Huisman a a
Department of Diagnostic Imaging, University Children’s Hospital Z¨urich, Steinwiesstr. 72, CH-8032 Z¨urich, Switzerland b Department of Paediatrics, University Children’s Hospital Z¨ urich, Steinwiesstr. 72, CH-8032 Z¨urich, Switzerland c University of Michigan Medical School, Ann Arbor, USA Received 26 January 2007; accepted 2 April 2007
Abstract Child abuse is a major problem worldwide. An early and reliable recognition and diagnostic work up is important for the management of these children and their caregivers. Radiological skeletal surveys in combination with brain imaging are mandatory in the initial evaluation. In selected cases, repeat radiography and/or bone scintigraphy is necessary. The radiation dose from these studies is significant. Whole-body STIR MR imaging permits evaluation of the entire skeleton and all viscera with a single examination while avoiding ionizing radiation. We report on a 2-month-old female suspected victim of child abuse in whom whole-body STIR MR imaging revealed multiple rib fractures suggestive of child abuse that were only partially recognised by conventional radiography. Our case suggests that whole-body STIR MR imaging should be considered as an alternative imaging modality in children in whom child abuse is suspected. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: MRI; Whole-body imaging; Trauma
1. Introduction The World Health Organization (WHO) recognises child abuse as a major problem worldwide. Although data are difficult to acquire, the WHO estimates that worldwide 40 million children aged 0–14 years are abused or neglected [1]. Early and reliable recognition of child abuse is mandatory and accurate imaging is essential in making the diagnosis [2–4]. However, false positive imaging studies are troublesome as they may have immense unwanted social, psychological, medical and legal consequences for the child and caregivers. On the other hand, false negative studies may result in continuation of child abuse which may impact the child’s future physical and psychological health. ∗ Corresponding author at: Department of Diagnostic Imaging, University Children’s Hospital Z¨urich, Steinwiesstrrasse 75, CH-8032 Z¨urich, Switzerland. Tel.: +41 44 2667500; fax: +41 44 2667158. E-mail address: [email protected] (C.J. Kellenberger).
1571-4675/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2007.04.001
Depending on the age of the child different patterns of injury may be observed. Very young children commonly present with “shaken baby syndrome”, a well-defined constellation of injuries that includes severe shearing injuries of the brain and hypoxia, damage to the spinal cord and neck, and fractures of the ribs. In older children, other fractures are more frequent [2]. Unusual radiological findings, especially traumatic lesions that do not match the clinical and/or trauma history, multiple fractures of different ages and fractures in unusual locations should alert the radiologist. Specific lesions such as posterior rib fractures, metaphyseal lesions, scapular fractures, spinous process fractures and sternal fractures are especially suggestive of child abuse [2,5]. A complete radiological skeletal survey is a wellestablished imaging modality in the diagnostic work up of children suspected for non-accidental trauma [2–4]. Computed tomography (CT) and magnetic resonance (MR) imaging are added if traumatic brain injury is suspected. Repeat radiographs or bone scintigraphy may be considered in those cases where non-accidental trauma is strongly
44
E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47
suspected but initial imaging is negative [3,4]. It is well known that acute fractures may not be apparent or may be overlooked on early radiographs. The radiation dose of repeat radiographs and/or bone scintigraphy is significant [6]. Therefore, alternative imaging modalities devoid of ionizing radiation are necessary in these young patients. Wholebody imaging with short tau inversion recovery (STIR) MR sequences has proven its value as a survey imaging technique for various non-traumatic indications [7–10]. Here we report on a 2-month-old female suspected victim of child abuse in whom multiple acute posterior and lateral rib fractures were identified by whole-body STIR MR imaging.
2. Case report A 2-month-old girl was presented to the emergency department of our children’s hospital because of a recent increase in “fussiness and crying”, most noticeably at night. Symptoms reportedly started 2 weeks prior to presentation. The girl was born at 34 weeks of gestation, and the postnatal period was unremarkable. On physical examination, one haematoma was seen on the forehead (4 cm × 2 cm); a second was seen on the left cheek (1 cm × 1 cm). There were no petechiae or ecchymoses and the child otherwise appeared well. Vitamin K had been administered appropriately. Family history was unremarkable for hereditary coagulopathies. According to the mother, there was no history of trauma and the patient had remained exclusively in her parents’ care. Cranial CT revealed a subacute, focal subarachnoid haemorrhage within the right sylvian fissure (Fig. 1). No additional posttraumatic intracranial lesions were observed. The overlying skull was intact and no shearing injuries were seen. Chest/abdomen radiography showed focal widening of the lateral 6th to 8th ribs on the left and possibly of the posterior 9th rib on the right. In addition, discrete pleural thickening or effusion was seen on the left (Fig. 2). The multifocality of the chest lesions, the unusual intracranial finding and the discrepancy between the cranial CT findings and clinical symptoms as well as the facial haematomas raised the suspicion of child abuse and prompted an MR examination of the brain. Whole-body STIR imaging was added in order to detect additional skeletal or soft tissue injuries that would support the diagnosis of non-accidental trauma. MR imaging was performed on a 1.5 Tesla MR unit (General Electric Medical Systems, Milwaukee, Wisconsin, USA). The girl was examined under sedation with propofol. Brain imaging was performed according to the routine departmental trauma protocol. For the whole-body imaging, we used an eightchannel cardiac phased array surface coil. Three overlapping STIR sequences were acquired in the coronal plane covering the girl from the vertex to the feet. Imaging parameters were derived from previously published whole-body STIR imaging protocols [10]. MR imaging of the brain confirmed the CT findings. The signal characteristics (T1-hyperintense, T2- and T2*-
Fig. 1. Axial CT of the brain shows hyperdense subarachnoid haematoma within the right sylvian fissure. No additional lesions, no midline shift, no skull fracture.
hypointense) indicated that the subarachnoid haemorrhage was 1–2 weeks old. No additional posttraumatic intracranial lesions were seen. In addition, lesions that could have explained a spontaneous haemorrhage (e.g. an aneurysm, vascular malformation or tumour) were excluded. Whole-body STIR imaging revealed more extensive lesions of the chest wall than did radiography (Fig. 3). Not only did it confirm the previously identified lesions of the lateral 6th to 8th ribs on the left, but also showed hyperintense signal within the marrow space and in the surrounding soft tissue of multiple posterior ribs bilaterally. The posterior 10th rib on the right showed an irregularly thickened hypointense contour and also hyperintense signal in the adjacent soft tissue. In addition, the bone marrow signal of the left distal radial and ulnar metaphyses was slightly increased. The remainder of the skeleton, soft tissues and parenchymal organs showed normal signal. Selected follow-up radiographs were performed 2 weeks later. The chest radiograph confirmed the rib fractures by showing callus formation along the lateral 6th to 8th rib on the left (Fig. 4) and along the posterior ribs bilaterally. The radiograph of the forearm was unremarkable.
3. Discussion Child abuse or non-accidental trauma is frequently unrecognised, misrecognised or under recognised. The shortand long-term outcomes and physical and psychological sequelae may be devastating for the child and their sib-
E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47
Fig. 2. Frontal chest/abdomen radiograph shows widening of the left lateral 6th to 8th ribs with adjacent pleural thickening and possible focal thickening of the right posterior 9th rib suggesting multiple rib fractures.
45
lings. An early and reliable diagnosis is a sine qua non [2–5]. Skeletal surveys encompassing multiple conventional radiographs and a brain CT as well as possible follow-up radiographs or additional bone scintigraphy represent a significant radiation dose to the child. A skeletal survey with 16 films using computed radiography has about 0.16 mSv of radiation [4]. The effective dose equivalent for a bone scan is about 0.11 mSv/MBq in newborns, 0.042 mSv/MBq for 1-year-old infants and 0.021 mSv/MBq for 5-year-old children [6]. Skeletal radiographs may overlook subtle acute osseous lesions. Fractures near the growth plates, the classic metaphyseal lesions, may be difficult to detect on bone scintigraphy because of the high degree of tracer uptake of the normal growth plate [4]. In addition, soft tissue lesions, with the exception of calcified haematomas, are seldom radiographically visible [4]. Consequently, an alternative imaging modality should be considered that preferably does not use ionizing radiation, is widely available, images the entire child, and allows visualisation of both the bone and soft tissues. Whole-body STIR MR imaging fulfils most of these requirements. Several studies have shown the value of wholebody STIR MR imaging in adults for detecting metastatic bone disease, staging of breast carcinoma and for assessment of multifocal diseases such as polymyositis [7–9]. In a series of 140 children, whole-body STIR MR imaging has been shown to be a sensitive radiation-free screening technique for assessing skeletal, bone marrow and soft tissue disease in a reasonable time [10]. Several researchers have suggested that whole-body STIR MR imaging may have a role in the assessment of child abuse [8,9]. In this setting, one single non-ionizing imaging modality could be used to assess for brain, visceral and skeletal injuries [9,10]. To the best of our knowledge, this is the first report on the use of whole-body STIR MR imaging in child abuse and its findings. Our case shows that the whole-body STIR technique can easily identify fractures by the hyperintense signal in the bone marrow and adjacent soft tissue. Lesion conspicuity is high because of the contrast between the hyperintense
Fig. 3. Selected coronal STIR images show hyperintense signal in the bone marrow of lateral ribs on the left, of posterior ribs bilaterally and increased signal in the surrounding soft tissue. The 10th rib on the right shows an irregular hypointense contour. Arrows indicate respective ribs.
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E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47
Fig. 4. Comparison (a) initial chest radiograph; (b) coronal STIR image; (c) follow-up chest radiograph. Callus formation confirms rib fracture.
traumatic lesion and the relatively low signal of normal tissues, which is inherent to the STIR sequence. Oedematous or proton-rich tissues have prolonged T1 relaxation and T2 decay times, resulting in high signal intensities on STIR imaging, whereas the signal from fat is suppressed by an initial 180◦ inverting pulse which nulls the longitudinal magnetization of fat at the time of the 90◦ excitation pulse [10]. In our case, STIR MR imaging was more sensitive than radiography. The STIR images revealed a more extensive chest wall injury with more rib fractures than seen on the initial radiograph, which were eventually confirmed on the follow-up radiograph. Further, STIR images revealed increased signal in the left distal radial and ulnar metaphyses suggesting fractures, which however were not confirmed by follow-up radiography. Although this could be a false positive MR finding, the STIR technique might have shown minor bone bruises which only resulted in minimal reparative processes not depicted on the follow-up radiographs. The true sensitivity and specificity of STIR MR imaging for detecting the different kinds of fractures encountered in non-accidental trauma need to be studied in larger prospective studies. Whole-body STIR MR imaging has several limitations. Although overt parenchymal lesions of the brain, lungs, liver, spleen, and kidneys can readily be detected, smaller parenchymal lesions may be missed due to the relatively low spatial resolution. Currently, whole-body STIR MR imaging cannot replace dedicated brain MR to exclude intracranial lesions, but can easily be added to brain MR examinations. The STIR technique is not specific for traumatic lesions because any inflammatory, infectious or neoplastic lesion with increased water content or protein concentration shows high signal. Therefore, the MR findings need to be interpreted in context with the clinical setting and other imaging results. Infants and small children require sedation for an MR study.
Finally, critically injured children are not easily accessible within the bore of the magnet, which can be troublesome in the emergency setting. In conclusion, whole-body STIR MR imaging is a radiation-free technique covering the entire body that is sensitive for traumatic lesions suggestive of child abuse, such as lateral and posterior rib fractures. The high lesion conspicuity allows depiction of radiographically occult bone and soft tissue lesions in an early phase. Currently, whole-body STIR MR imaging cannot replace a skeletal survey, but should be considered as alternative imaging technique in cases where follow-up radiographs or bone scintigraphy are indicated. This will reduce radiation exposure to small children significantly. Prospective studies are required to determine the value of whole-body STIR MR imaging in the diagnostic work up of children suspected of non-accidental trauma.
References [1] WHO recognises child abuse as a major problem. The Lancet 1999;353(9161):1340. [2] Kleinman PK. Diagnostic imaging of child abuse. Baltimore: Williams & Wilkins; 1987. [3] Kleinman PK, Nimkin K, Spevak MR, et al. Follow-up skeletal surveys in suspected child abuse. AJR Am J Roentgenol 1996;167(4):893–6. [4] Mandelstam SA, Cook D, Fitzgerald M, Ditchfield MR. Complementary use of radiological skeletal survey and bone scintigraphy in detection of bony injuries in suspected child abuse. Arch Dis Child 2003;88(5):387–90. [5] Bulloch B, Schubert CJ, Brophy PD, Johnson N, Reed MH, Shapiro RA. Cause and clinical characteristics of rib fractures in infants. Pediatrics 2000;105(4):E48. [6] Hahn K, Fischer S, Colarinha P, et al. Guidelines for bone scintigraphy in children. Eur J Nucl Med 2001;28(3):42–7.
E. Stranzinger et al. / European Journal of Radiology Extra 63 (2007) 43–47 [7] Eustace S, Tello R, DeCarvalho V, et al. A comparison of whole-body turbo STIR MR imaging and planar 99mTc-methylene diphosphonate scintigraphy in the examination of patients with suspected skeletal metastases. AJR Am J Roentgenol 1997;169(6):1655–61. [8] O’Connell MJ, Powell T, Brennan D, Lynch T, McCarthy CJ, Eustace SJ. Whole-body MR imaging in the diagnosis of polymyositis. AJR Am J Roentgenol 2002;179(4):967–71.
47
[9] Hargaden G, O’Connell M, Kavanagh E, Powell T, Ward R, Eustace S. Current concepts in whole-body imaging using turbo short tau inversion recovery MR imaging. AJR Am J Roentgenol 2003;180(1):247– 52. [10] Kellenberger CJ, Epelman M, Miller SF, Babyn PS. Fast STIR whole-body MR imaging in children. Radiographics 2004;24(5):1317– 30.