Pancreatic Trauma
Total Page:16
File Type:pdf, Size:1020Kb
Pancreas Trauma Dr. Michael R Aquino, MD, MHSc Assistant Professor of Medical Imaging Sick Kids Hospital, Toronto, ON, Canada I have no potential conflicts of interest to disclose. Learning Objectives • Identify the role of each imaging modality in the evaluation of pediatric patients with suspected blunt injury to the pancreas • Compare the advantages and disadvantages of each imaging modality used to evaluate the pediatric pancreas after blunt trauma • Describe how various techniques utilized in each modality could affect sensitivity and specificity for detecting pancreatic injury Management of Blunt Pancreatic Injury Injury Description of Injury Grade Minor contusion without duct injury I Superficial laceration without duct injury NON-OPERATIVE Major contusion without duct injury or tissue loss II Major laceration without duct injury or tissue loss NON-OPERATIVE VS OPERATIVE DEBATED III Distal transection or parenchymal injury with duct injury Large studies with conflicting findings IV Proximal transection or parenchymal injury involving ampulla NON-OPERATIVE PREFERRED Operative option is Whipple – more morbid operation which may have V Massive disruption of pancreatic head adverse long-term consequences Role of CT • Primary modality for evaluation of suspected blunt traumatic abdominal and pelvic injury in hemodynamically stable pediatric patients • Multiple algorithms / tools available to help decide which patients should be imaged CT Evaluation of Blunt Injury to the Pancreas • Main pancreatic duct integrity predicted based on depth of laceration • CT-based grading introduced by Wong Y, et al. CT Grade CT Findings A Pancreatitis and/or superficial laceration BI Deep laceration at distal pancreas BII Transections at distal pancreas CI Deep laceration at proximal pancreas CII Transection at proximal pancreas • Laceration >50% depth suspected to involve main pancreatic duct • Thought to be more reliable for body and tail, less reliable for head CT Evaluation of Blunt Injury to the Pancreas • Questionable accuracy of CT for identifying main pancreatic duct disruption • A few single center, small sample studies demonstrate high sensitivity • Phelan HA, et al. • Large multicenter retrospective study of MDCT for detecting pancreatic injury • Sn 52-54%, Sp 90-95% • CT unreliable in first 12-24 hours • Minimal early reactive edema • Close apposition of pancreatic transection fragments • Obscuration of laceration by surrounding hemorrhage, edema CT Protocol for Blunt Abdominal Trauma • FOV: Lower chest above diaphragms to symphysis pubis • Phase: Portal-venous • Contrast: IV contrast (2 mL/kg, max 120 mL), NO oral contrast • Image acquisition: • 0.625 mm • Reconstructed to 5 mm axial, and 3 mm coronal and sagittal images CT Protocol for Blunt Abdominal Trauma • Data do not support routine use of oral contrast • Eillison AM, et al • Minimal increased specificity for detecting any intra-abdominal injury • 84.7% (95% CI 82.2%-87.0%) vs 80.8% (95% CI 79.4%-82.1%) • Phelan H, et al • Oral contrast does not result in significant improvement in sensitivity of CT for detecting pancreatic ductal injury • Use delays study, increases risk of aspiration, may cause artifacts from air- contrast levels CT Protocol for Blunt Abdominal Trauma • Data does not support need for multiphasic pancreas protocol • Wong Y, et al • Single center, small sample prospective study with 6 proven duct injuries • Portal venous phase identified 6/6 duct disruptions and 3/3 normal ducts • Arterial/Parenchymal phase 2 false positives • Delayed/equilibrium phase 3 false negatives • Phelan HA, et al • Multicenter, retrospective study of MDCT detection of pancreas injury • Dedicated multiphasic pancreas protocol performed in 11% of cases but not associated with significant increase in sensitivity CT Protocol for Blunt Abdominal Trauma • Slice thickness • Phelan HA, et al • Multicenter, retrospective study of MDCT detection of pancreas injury • ~22% of studies with slice thickness ≤3 mm • No significant difference in sensitivity between studies with slice thickness ≤3 mm and ≥5 mm • Anderson S, et al & Itoh S, et al, & Faria S, et al • Several non-trauma-related studies demonstrate significant improved visualization of the main pancreatic duct with the use of thin-section MDCT (0.5 mm – 1.25 mm) • Panda A, et al • Single center study MDCT using 1.5 mm slice thickness and curved multiplanar reformatted images identified 18/19 duct disruptions • Must consider increased radiation exposure, noise, time to process CT Protocol for Blunt Abdominal Trauma • Curved planar reformations • Fukushima H, et al • Non-trauma-related studies have demonstrated improved visualization of the main pancreatic duct with the use of curved planar reformats • Panda A, et al • Recent single center study MDCT using 1.5 mm slice thickness and curved multiplanar reformatted images identified 18/19 duct disruptions • Requires time, post-processing Role of MRCP • Complementary to CT • Noninvasive technique to assess ductal integrity with high accuracy • Heavily T2-weighted sequences facilitate visualization of pancreaticobiliary tree MRCP Evaluation of Blunt Injury to Pancreas • Several predominantly adult studies demonstrate high sensitivity and specificity for identifying main pancreatic duct injury • Drake LM, et al • 31 patients with MRCP • Sn 91%, Sp 100% • Panda A, et al • 17 patients with MRCP, 3 pediatric • Sn 92%, Sp 100% • Houben C, et al • MRCP identified duct injury in 4 patients that had subsequent ERCP MRCP vs ERCP • MRCP • Noninvasive • Depicts entire abdomen including pancreatic parenchyma, peripancreatic fluid • Image duct upstream of injury • ERCP • May be diagnostic AND therapeutic • Potential for procedural complications • Ionizing radiation • May not be readily available MRCP Protocol Sequence Plane TR (ms) TE (ms) FOV (cm) Matrix Slice Thickness Respiration Compensation 3D T2 TSE Coronal 1000 864 ~30 256 x 205 2 mm, 1 mm gap Respiratory-triggered Fat Suppressed 2D T2 SS TSE Coronal 1000 740 ~30 320 x 256 40 mm radial slabs Breath-hold in older children, Fat Suppressed Radial angle 12.83 degree manual during shallower respiration in younger children 2D T2 SS TSE Coronal 3000 160 ~20 184 x 178 3 mm Respiratory-triggered Axial 3000 160 ~25 228 x 235 3 mm 3D T1 TFE Axial 500 50 ~20 320 x 256 1.5 mm Breath-hold Fat Suppressed 2D bSSFP Axial 500 50 ~37 268 x 429 5 mm TI 120 ms Respiratory-triggered 2D T2 TSE SPIR Axial 2000 80 ~37 376 x 300 5 mm, 1 mm gap Respiratory-triggered Fat Suppressed • Cardiac coil or pediatric body coil MRCP Protocol • No IV or oral contrast • No secretin MRCP Protocol • Smallest coil appropriate for size of child • Cardiac coil or pediatric body coil • Appropriate FOV to improve SNR • Effective respiratory compensation techniques • Fasting 4-6 h to reduce artifact from gas and fluid in adjacent bowel MRCP Protocol • 3.0T vs 1.5T • 3.0T high signal-to-noise ratio • Improved spatial resolution • Reduced scan time • More prone to dielectric effects and susceptibility artifacts • Isoda H, et al. & O’Regan DP, et al. • Significant improvement in image noise, SNR, and qualitative image quality at 3.0T • Trend but statistically insufficient improved visibility of the pancreatic duct at 3.0T • Onishi H, et al. • Significant improvement in visualization of pancreatic duct • No significant difference in homogeneity of signal intensity • Almehdar A and Chavahan G • Pediatric study demonstrated diagnostic quality of majority of MRCP exams sufficient to answer clinical question MRCP Protocol • 3D FSE vs SSFSE radial slab • 3D sequences with higher spatial resolution, higher SNR, MIP • Longer acquisition requiring respiratory triggering/navigator gating • Chavhan G, et al. • Pancreatic duct visualization better on SSFSE radial slab vs 3D FSE • Similar result in adult study by Lavdas E, et al. MRCP Protocol • Secretin • Stimulates pancreatic exocrine secretion, increases tone at sphincter of Oddi • Trout A, et al. • Minimal objective increase in pancreatic duct diameter • No significant subjective difference in image quality or pancreatic duct visibility • Gillams AR, et al. • Measured peripancreatic fluid collections after secretin administration in patients with pancreatic injury • Contributed to management of 12/17 patients; confirmed disruption and ongoing leak Role of US • FAST may have a role in triaging hemodynamically unstable • Holmes JF, et al. • Compared with standard care, FAST did not improve clinical care or resource utilization in hemodynamically stable children with blunt torso trauma • CT remains gold-standard imaging modality to evaluate blunt abdominal trauma in children Role of US • Naik-Mathuria BJ, et al. (Pediatric Trauma Society) • Proposed clinical pathway for nonoperative management of high-grade pediatric pancreatic injuries • US indicated in patients with progression/persistence of symptoms, worsening enzyme levels, inability to tolerate diet after a week, follow-up fluid collections US Evaluation of Blunt Injury to the Pancreas • Poor sensitivity for detecting pancreatic injury • Retroperitoneal midline position • Separation of transection fragments facilitates visualization • Useful for evaluating peripancreatic fluid CEUS of Blunt Injury to the Pancreas • Possible role in patients with low-energy impact trauma and isolated abdominal organ injuries, follow-up • Sessa B, et al. • Sn 96%, Sp 99%, PPV 98%, NPV 98% for detecting traumatic abdominal injury • LV F, et al. • Detected 21/22 blunt pancreatic injuries, including 6/7 ductal injuries Pancreas Trauma.