List of Abbreviations
CHD Common Hepatic Duct
CBD Common Bile Duct
SV Splenic Vein
PV Portal Vein
SMA Superior Mesentric Artery
IMA Inferior Mesentric Artery
IVC Inferior Vena Cava
HU Hounsfield Unit
UGD Urogenital Diaphragm
MPR Multiplanar Reconstruction
MIP Maximum Intensity Projection
VR Volume Rendering
mGy milliGray
Gy Gray
CTDI Computed Tomography Dose Index
mA milliAmpere
AAST American Association for the Surgery of Trauma
UPJ Ureteropelvic Junction
BAT Blunt Abdominal Trauma
BDR Blunt Diaphragmatic Rupture
List of Tables
Table no. Title Page
1 Showing the difference between jejunum and ileum. 15
2 American Association for the Surgery of Trauma Spleen injury Grading System. 43
3 Demographic and injury characteristics of the studied sample. 68
4 Presence of multiple and isolated organ involvement in the studied sample. 70
5 Free peritoneal fluid as detected by Focused Assessment with Sonography in Trauma (FAST) in the studied sample. 72
6 Free peritoneal fluid as detected by Multiple Detector Computed Tomography (MDCT) in the studied sample. 73
7 Focused Assessment with Sonography in Trauma (FAST) sensitivity, specificity and accuracy in detection of free peritoneal fluid. 74
8 Organ involvement as detected by Multiple Detector Computed Tomography (MDCT) in the studied sample. 75
9 Organ involvement as detected by operative findings in the studied sample. 76
10 Comparison between Multiple Detector Computed Tomography (MDCT) and operative findings regarding organ involvement in the studied sample. 77
11 Multiple Detector Computed Tomography (MDCT) sensitivity, specificity and accuracy in detection of liver involvement. 78
12 Multiple Detector Computed Tomography (MDCT) sensitivity, specificity and accuracy in detection of splenic involvement. 79
13 Multiple Detector Computed Tomography (MDCT) sensitivity, specificity and accuracy in detection of renal involvement. 80
14 Multiple Detector Computed Tomography (MDCT) sensitivity, specificity and accuracy in detection of bladder involvement. 81
15 Multiple Detector Computed Tomography (MDCT) sensitivity, specificity and accuracy in detection of bowel involvement. 82
List of figures
Fig. no. Title Page
1 Layers of abdominal wall. 4
2 Median section through the abdomen to show the peritoneal cavity. 5
3 Portal venous drainage. 7
4 Hepatic arterial supply. 7
5 Segmental anatomy of the liver. 8
6 Pancreas anatomy. 9
7 Anatomy of the splenic artery. 10
8 Arteries of Kidney and suprarenal gland. 11
9 The trigone. (A) Superolateral view . (B) Anterior view . 12
10 (A) Female urethra. (B) Male urethra. 13
11 Colon Anatomy. 16
12 Arterial Supply of the gut. 17
13 Main branches of (SMA & IMA). 17
14 Axial CT of normal abdomen. 26
15 Axial CT of normal mid abdomen. 26
16 Axial CT of a normal male pelvis. 27
17 Axial CT of a normal female pelvis. 27
18 Coronal CT of a normal abdomen. 28
19 A diagram showingthe collimator. 31
20 Contrast-enhanced CT: there is frank arterial bleeding from the splenic artery associated with a fragmented spleen. 38
21 Contrast-enhanced axial CT scans in 34-year-old man involved in motor cycle accident. Transverse images in, A, arterial, B, portal venous, and, C, delayed phases show hyper attenuating contrast material (arrow) that persists and progressively enlarges at subsequent delayed imaging. Findings were consistent with active extravasation. Patient underwent splenectomy. 38
22 MDCT appearance of lateral abdominal wall hematoma. 39
23 Subcapsular hematoma following blunt abdominal injury.Axial CT acquired during the portal venous phase shows a focal subcapsular elliptical hematoma in the right lobe of the liver. 41
24 (A) Grade II liver laceration. (B) GradeIIIliver laceration. 41
25 Pancreas appears to be fractured (Arrow) There was disruption of main pancreatic duct. 42
26 Axial CECT scan shows grade I spleen injury. A subcapsular hemorrhage (arrow) less than 10% of surface area. 44
27 Axial CECT scan shows grade II spleen injury. An intraparenchymal haematoma (arrow) less than 4 cm in diameter with no capsular tear. 44
28 Axial CECT scan shows grade III spleen injury. A 6cm laceration at the upper pole of the spleen (arrow). 44
29 Coronal reformatted CECT shows grade IV spleen injury. Multiple lacerations causing major devascularisation of the spleen. 45
30 Axial CECT scan shows grade V splenic injury. Shattered spleen with large volume haemoperitoneum. Note the focal high attenuation (arrow) due to active hemorrhage. 45
31 Axial CECT shows grade V splenic injury. A non-perfusion of the spleen on this post contrast image. Perisplenic hyperdensity (short arrow) is due to contrast extravasation. There is also left renal injury (long arrow). 45
32 CT Image shows splenic laceration with perisplenic hematoma. 46
33 Grade 1 renal injury, contusion. Contrast-enhanced MDCT scan of the abdomen shows ill-defined area of hypo enhancement in the medial aspect of right kidney (black arrow). 48
34 Right renal laceration extending into the collecting system (grade IV injury) in a 34-year-old man who was involved in a motor vehicle accident.(a) Cortico-medullary phase CT scan shows a small amount of fluid along the posterior surface of the right kidney (arrow), a finding that was the only clue to the presence of a laceration. (b) Delayed excretory phase CT scan shows a subtle area of urinary extravasation (arrow) 49
35 Grade 5 renal injury. Partial UPJ tear and multiple deep
laceration. 49
36 Two cases of extra-peritoneal bladder rupture (CT scan demonstrates contrast material and hematoma extending along the anterior abdominal wall within the space of Retzius (arrows) 51
37 Type I urethral injury: disrupted prostatic parenchyma(p)with surrounding hematoma (h) 52
38 Distortion or obscuration of the UGD fat plane.(a)CT scan of a patient with a type II urethral injury shows partial absence of the left UGD fat plane (arrow) with a normal right fat plane. (b) CT scan of another patient shows a fracture of the right ischiopubic ramus (arrow) with preservation of the contour and surrounding fat planes of the UGD (arrowheads). 53
39 Type III urethral injury ; CT scan obtained through the perineal region shows extravasated contrast material (arrows) in the urinary tract below the UGD.
53
40 Left image : distorted contour of the bulbocavernosus muscle (arrowheads) with anobscured fat plane. Note the air in the urethra. Right image : a fracture of the left ischiopubic ramus with preserved fat planes (arrowheads) and no hematoma of the ischiocavernosus (arrow) or bulbocavernosus muscle. The patient had no urethral injury. 54
41 Portal venous phase CT showing bilateral adrenal gland hematoma. 55
42 Axial CT image showing a tear in the anterior gastric wall. 56
43 Coronal portal phase CECT showing duodenal hemorrhage. 57
44 CT abdomen. 1. Fluid collection. 2. Extra-luminal gas. 3. Bowel wall thickening. 58
45 Sagittal CT of portions of the involved dissecting aorta with arrows indicating the dissecting intimal flap. 61
46 Traumatic rupture of the external iliac artery (a-b) CT-angiography images show the rupture of the right external iliac artery with contrast medium extravasation into the iliac muscle. (c) Volume Rendering reconstruction (anterior-posterior view) from the same CT study confirms the contrast medium extravasation (white circle). 62
47 IVC traumatic injury (a) Arterial phase axial CT image depicts a hematoma (arrow) around the IVC; coexist multiple hepatic and splenic parencymal lacerations. (b) Venous phase axial CT image from the same study confirm the IVC hematoma (arrow). (c) Follow-up axial CT image show the presence of endovascular stent in IVC with reestablished caliber (arrow). 63
48 a) Axial contrast-enhanced CT image shows herniation of the liver(L), (GB), abdominal fat,and bowel loops through the diaphragmatic defect. The bowel contacts the posterior thoracic wall (dependent viscera sign). Note the severe thickening of the gallbladder wall (arrow). (b) Coronal contrast-enhanced CT image helps confirm herniation of the gallbladder and part of the liver into the thorax (herniation through a defect sign). Thickening of the gallbladder wall (arrow) is better depicted on this coronal image than in axial. 64
49 Shows the age distribution of the studied sample. 69
50 Shows the gender distribution of the studied sample. 69
51 Shows the organ involvement in the studied sample. 71
52 Comparison between Focused Assessment with Sonography in Trauma (FAST) and Multiple Detector Computed Tomography (MDCT) findings in the studied sample. 73
53 Case I 83
54 Case II 85
55 Case III 87
56 Case IV 89
57 Case V 91
58 Case VI 93
59 Case VII 95
60 Case VIII 97
61 Case IX 99
62 Case X 101
Introduction
Introduction
Trauma is a significant public health problem, representing the third leading cause of death in the United States. Trauma is also the leading cause of mortality in patients under the age of 40 years. With the widespread availability of multi-detector computed tomography in trauma centers, the traditional workup of trauma patients has changed. Blunt chest injuries are now frequently studied with MDCT to evaluate the aorta, and workup of the blunt trauma victim with abdominal injury is evolving with MDCT. (1-3)
now allows not only the detection of injuries but provides new information on the severity of injuries with improved detection of vascular injury manifested by “active “. Today, often performed in patients with blunt trauma in order to best identify vascular injuries prior to surgical intervention. (2)
Evaluation of the abdomen and pelvis with MDCT is currently performed differently in different institutions. Some studies advocate the use of a “whole-body” CT in the trauma patient. They utilize a continuous scanning technique through the areas to be scanned, such as abdomen, and pelvis. Others continue to perform separate MDCT data acquisitions for each type of CT, facilitating the optimization of contrast enhancement timing and radiation dose. Sequential rather than continuous scanning makes possible the use of different types of reconstruction algorithms for different anatomical segments. (5-7)
Introduction
A trauma surgeon an be provided definitive information concerning aortic injuries almost immediately with MDCT without the additional contrast load and invasiveness of traditional ways .(4)
it can detect the solid organ injury, free fluid, and evaluating injuries to pancreas, bowel, kidney, adrenal, mesentery, diaphragm, vascular and spine injury. The primary advantage of CT scanning is its high specificity and use for guiding non-operative management of solid organ injuries. In addition, a CT scan of the abdomen can reveal other associated injuries, notably vertebral and pelvic fractures and injuries in the thoracic cavity. (8)
Aim of the Work
AIM OF THE WORK
The aim of this work is to evaluate the prognostic role of MDCT in patients with blunt abdominal trauma in order to improve the therapeutic approaches and outcome of those patients.
Gross Anatomy
The abdomen is the part of the trunk inferior to the thorax. It has musculo-membranous walls surround a large cavity , which is bounded superiorly by the diaphragm and inferiorly by the pelvic inlet. The abdominal cavity may extend superiorly as high as the fourth intercostal space, and is continous inferiorly with the pelvic cavity. It contains the abdominal viscera.
I ) ABDOMINAL WALL
The abdominal wall covers a large area. It is bounded superiorly by the xiphoid process and costal margins, posteriorly by the vertebral column, and inferiorly by the upper parts of the pelvic bones.
(9) .The abdominal wall is a laminated structure. The different layers are skin, superficial fascia, subcutaneous fat, muscle layer, the transversalis fascia, and a layer of extraperitoneal fat (Fig.1). The anterior muscle layer is composed of paired midline rectus muscles and anterolaterally situated internal and external oblique and transverse abdominis muscles.
(Fig. 1)
Gross Anatomy
Peritoneal cavity is a peritoneal space within the abdomen and pelvis lines with peritoneum.. Peritoneum is a Single layer of mesothelium that covers a thin layer of connective tissue, Parietal peritoneum that lines the abdominal and pelvis muscle walls; visceral peritoneum covers the bowel (serosa) and abdominal viscera. Abdominal viscera either are suspended in the peritoneal cavity by folds of peritoneum (mesenteries) or are outside the peritoneal cavity. Organs suspended in the cavity are referred to as intraperitoneal; organs outside the peritoneal cavity, with only one surface or part of one surface covered by peritoneum, are retroperitoneal. (10)
Fig.(2) Median section through the abdomen to show the peritonealcavity. (11)
The transverse mesocolon divides the peritoneum into the supramesocolic and inframesocolic spaces; the bilateral paracolic and pelvic spaces are also peritoneal spaces. (11)
Gross Anatomy
A )Supramesocolic compartment
Divided arbitrarily into right and left supramesocolic peritoneal spaces, which can be further subdivided into a number of subspaces that are in communication.
1 . Right supramesocolicspace :-
Right subphrenic space
Right subhepatic space
Lesser sac
2 . Left supramesocolicspace :-
Four arbitrary subspaces, which are in communication
Anterior left perihepatic space
Posterior left perihepatic space (gastrohepatic recess)
Anterior left subphrenic space
Posterior left subphrenic (perisplenic) space
B )Inframesocolic compartment
Divided into two unequal spaces posteriorly by the root of the small bowel mesentery into right and left inframesocolic space.(11)
II ) Liver:
The liver is about 2% of body weight in the adult, which amounts to approximately 1400 g in females and 1800 g in males. The liver receives its blood supply from two sources: 80% is delivered by the portal vein (Fig. 4), which drains the spleen and intestines, the remaining 20%, the oxygenated blood is delivered by the hepatic artery (Fig. 5), externally, and the liver is divided by the falciform ligament into a larger right lobe and a smaller left lobe. (12)
Gross Anatomy
(Fig.3)
(Fig.4)
Gross Anatomy
(Fig. 5) Segmental anatomy of the liver(12)
III ) GB
The gallbladder is a piriform (pear-shaped) organ that straddles the under surface of segments IVB and V of the liver. It has an inferior peritoneal surface and a superior hepatic surface that is closely applied to the gallbladder bed in the liver. The part of the gallbladder projecting beyond the undersurface of the liver is called the fundus, which continues into the main body of the gallbladder. The body of the gall bladder narrows into a neck, which leads through an infundibulum to the cystic duct, An inferior sacculation (outpouching) of the gallbladder neck is sometimes present; this is called Hartmann‟s pouch, The right and left hepatic ducts join outside the liver in its hilum (portahepatis) to form the common hepatic duct (CHD). The cystic duct joins the CHD to form the common bile duct (CBD), which travels downward in the HDL along with the hepatic artery to its right and the portal vein behind it.(13)
IV ) The pancreas
It is a non capsulated, retroperitoneal structure that lies in the anterior pararenal space between the duodenal loop and splenic hilum
Gross Anatomy
with a length over 12.5 to 15 cm. The head, uncinate process, neck, body and tail constitute different parts of pancreas. Superior mesenteric vessels course posterior to the neck of the pancreas. It comprises exocrine and endocrine tissues. The antrum of the stomach lies usually across the midline anterior to the pancreas with the gastric body lying anterior to the pancreatic tail (Fig.6)(14)
Transverse mesocolon attaches posteriorly to the anterior pancreas head, body and proximal tail. The abdominal aorta runs posterior to the body of the pancreas, The celiac artery arises from the aorta at the superior border of the pancreas and divides into left gastric, common hepatic and splenic arteries, The SV arises from its origin at splenic hilum and runs along the postroinferior aspect of the pancreas to join superior mesenteric vein behind the neck of the pancreas to form the PV. The PV runs toward the portahepatiscephaled to the head of the pancreas. (14)
(Fig.6)
Gross Anatomy
V ) Spleen
Spleen is an important lymphatic organ in the human body. Its immunological and haematological functions are being well realized nowadays. It is situated in the left hypochondrium and partly in the epigastrium, between the fundus of the stomach and the diaphragm. The shape of the spleen varies from a slightly curved wedge to a domed tetrahedron . The size and weight of the spleen vary with age . In adults, it is usually 12 cm long, 7 cm broad and 3 to 4 cm wide. Its average adult weight is 150 gm, but the normal range is wide, between 80 and 300 gm .
(15)
(Fig. 7)
VI) Urinary system
A. Kidneys
Grossly, the kidneys are bean-shaped structures and weigh about 150 g in the male and about 135 g in the female. They are typically 10-12 cm in length, 5-7 cm in width, and 2-3 cm in thickness
(17)
Gross Anatomy
The relationship of neighboring organs to the kidneys is important, as described below: (17)
(Fig.8) Arteries of kidney and suprarenal gland(18)
B . Ureters
The ureters are paired muscular ducts with narrow lumina that carry urine from the kidneys to the bladder .The ureter is roughly 25-30 cm long in adults and courses down the retroperitoneum in an S curve. At the proximal end of the ureter is the renal pelvis; at the distal end is the bladder. The ureter begins at the level of the renal artery and vein posterior to these structures. This ureteropelvic junction usually coincides with the second lumbar vertebra on the left, with the right being lower.
(19)
Gross Anatomy
The ureter enters the pelvis, where it crosses anteriorly to the iliac vessels, which usually occurs at the bifurcation of the common iliac artery into the internal and external iliac arteries. Here, the ureters are within 5 cm of one another before they diverge laterally,The ureters then course out to the ischial spines before coursing medially to penetrate the base of the bladder. (19)
C . Urinary Bladder
The bladder is the most anterior element of the pelvic viscera. Although it is entirely situated in the pelvic cavity when empty, it expands superiorly into the abdominal cavity when full. The empty bladder is shaped like a three-sided pyramid that has tipped over to lie on one of its margins. It has an apex, a base, a superior surface, and two inferolateral surfaces. (20)
(Fig.9) The trigone.A.superolateralview.B. Anterior view(9)
Gross Anatomy
D . Urethra
( Fig.10)
In men (Fig.11-B) , the urethra is long, about 20 cm, and bends twice along its course, Beginning at the base of the bladder and passing inferiorly through the prostate, it passes through the deep perineal pouch and perineal membrane and immediately enters the root of the penis. As the urethra exits the deep perineal pouch, it bends forward to
Gross Anatomy
course anteriorly in the root of the penis. When the penis is flaccid, the urethra makes another bend, this time inferiorly, when passing from the root to the body of the penis. During erection, the bend between the root and body of the penis disappears. The urethra in men is divided into preprostatic, prostatic, membranous, and spongy parts. (20)
VII ) Adrenal Glands
The Adrenal Glands, belong to the endocrine system. They are a pair of triangular-shaped glands, each about 2 in. long and 1 in. wide, that sit on top of the kidneys. Each suprarenal gland is composed of 2 distinct tissues: the suprarenal cortex and the suprarenal medulla. The suprarenal cortex serves as the outer layer of the suprarenal gland, and the suprarenal medulla serves as the inner layer. These 2 major regions are encapsulated by connective tissue known as the capsule. (21)
VIII ) Gastrointestinal tract
A . Stomach
The stomach is J-shaped but varies in shape with the volume of its contents, with erect or supine position, and even with inspiration and expiration. The size and shape of the stomach also varies considerably from person to person. The stomach has two orifices – the cardia and the pylorus. The cardiac orifice or cardia is so-named because of its proximity to the heart and is the anatomic term for the junction of the esophagus and stomach. The radiological terms are gastro-esophageal junction, oesophagogastric junction and lower esophageal sphincter . The stomach has two curvatures the lesser and greater curves. The incisura is an angulation of the lesser curve. (22)
Gross Anatomy
B . Duodenum
Duodenum extends from pylorus to the duodenojejunal flexure, The first 2.5 cm of the duodenum-like the stomach- is attached to greater and lesser omentum, the remainder of the duodenum is retroperitoneal, and as a result, less mobile. It curves in a C-shaped around the head of the pancreas, it is described as having four parts: the first (superior), second (descending), third (horizontal), fourth (ascending). (23)
C . Small bowel
It begins where the intestine assumes a mesentery at the duodenojejunal flexure and ends at the ileo-caecal junction. It varies in length from 3 to 10 m, with an average length of 6 m. The root of its mesentery extends from the left of L2 to the right sacroiliac joint and is only 15 cm long. The small bowel lies in mobile coils in central abdomen. The proximal two fifths of the small intestine is called the jejunum and the distal three fifths the ileum, although the boundary between these is not well defined. (23)
Jejunum Ileum
Diameter Wider (3.0 to 3.5 cm ) Narrower (2.5cm)
Wall thickness Thicker Thinner
Position Left upper abdomen Right lower abdomen
Valvulae conniventes Thicker and more Thinner and less
prominent Prominent
Peyer`s patches Fewer and bigger More numerous
(Table. 1) A table showing the difference between jejunum and ileum
(23)
D. ) Large intestine
The length of the large intestine is very variable, with an average length of 1.5 m. it is wider in diameter than the small intestine,
Gross Anatomy
with a maximum diameter of the caecum at 9 cm and the transverse colon at 5.5 cm. As far as the rectum the colon is marked by taenia coli. The caecum is a blind pouch of large bowel distal to ileo-caecal valve. It is approximately 6cm long and usually has its own mesentery, making it mobile and easily distensible. The ascending colon runs from the ileocaecal valve to the inferior surface of the liver, where it runs medially into hepatic flexure. The transverse colon runs from the hepatic flexure across the midline to the splenic flexure, the descending colon runs from the splenic flexure inferiorly to the sigmoid colon. (23)
(Fig. 11) Colon Anatomy (24)
The sigmoid colon also has a mesentery. This is attached to the posterior abdominal wall to the left of the midline in an inverted V shaped whose limbs diverge from the bifurcation of the common iliac artery over the sacroiliac joint at the pelvic brim, The rectum has peritoneum anteriorly and laterally in its upper third and anteriorly only
Gross Anatomy
in its middle third. The lower third of the rectum is below the pelvic
peritoneum. (23)
(Fig.12)
(Fig.13)
Gross Anatomy
VII ) Aorta
The normal abdominal aorta has a clearly defined wall and smooth margins and tapers very slightly below the level of the renal arteries. The maximum infrarenal aortic diameter averages 2 cm in adults and varies little with respect to age, gender, race, and body size. The abdominal aorta lies adjacent to the spine throughout its course, slightly to the left of midline; In contrast, The lVC lies to the right of the midline and gradually moves away from the spine as it passes through the liver and diaphragm In the upper abdomen.(26)
VIII ) Inferior Vena Cava
IVC is formed by the confluence of the right and left common iliac veins draining blood from the lower extremities and pelvis. As it ascends in the retroperitoneum to the right of the abdominal aorta, the IVC receives major tributaries including the lumbar veins, the left and right renal veins, the right gonadal vein, and the hepatic veins. The azygos venous system connects to the IVC either directly or through the renal veins. (27)
IX) Diaphragm
The diaphragm consists of a large, dome-shaped central tendon with a sheet of striated muscle radiating from the central tendon to attach to the seventh through 12th ribs and to the xiphisternum . The two crura arise from the upper three lumbar vertebrae and arch upward and forward to form the margins of the aortic hiatus and esophageal hiatus. The diaphragm has a smooth dome shape in most individuals, but a scalloped outline is also common.(28)
CT Anatomy
CT ANATOMY
I ) Abdominal wall
CT provide excellent anatomical detail of the anterior abdominal wall in the axial plane. Contrast-enhanced CT (with or without oral contrast medium) is the method of choice to evaluate the peritoneal spaces, reflections and their contents. (9)
II ) Liver
The normal hepatic parenchyma has a relatively high density prior to contrast enhancement; higher than that of muscle and higher or equal in density to the spleen. On images taken without intravenous contrast medium, the hepatic veins and portal veins are seen as branching, low density structures coursing through the liver. As CT is a sectional technique, some of these branches may be seen as round or oval low-density areas, which should not be confused with metastases .(29)
After contrast enhancement, the veins opacify to become similar or higher in density than the surrounding parenchyma. Because the normal intrahepatic bile ducts are not visible and hepatic vessels opacify with contrast medium, the normal hepatic parenchyma after contrast shows either uniform density (29)
III ) GB
On computed tomography, the gallbladder neck is seen in higher cuts (sections) than the gall bladder body, which is seen higher than the gallbladder fundus.(13)
CT Anatomy
IV ) Pancreas
The pancreas is usually 15–20 cm in length and can be divided into four parts: the head, neck, body, and tail. Although there is no anatomic division between the tail and the body of the pancreas, both can be determined by measuring one-half of the distance between the neck and the end of the pancreas . Normal pancreas enhances strongly during the late arterial phase and washes out during the portal phase (30)
V ) Spleen
Normally, the spleen is located in the left hypochondrium. Its tissue composition made up of red pulp and white pulp explains the heterogenous aspect when contrast medium is injected in the arterial phase. This can make it difficult to detect intrasplenic masses. The adult spleen has no lobulations or incisures; however, the persistence of fissures separating the fetal spleen’s lobules can indicate splenic lacerations in a trauma context. (31)
The ectopic spleen is a migration of the spleen from its normal anatomic location because its ligaments have not developed properly. The spleen can migrate anywhere in the abdomen or pelvis. The accessory spleen can be found in 10% of the population; it is usually located near the hilum of the main spleen or the pacreatic tail. It can be located in many other places and be confused with a mass. The spleen is divided into several splenules of the same size. Splenosis is defined by the implantation of splenic tissues in the peritoneum following traumatic rupture of the spleen. (31)
VI ) Urinary System
A . Kidneys
An unenhanced CT should be performed routinely before administration of intravenous contrast in renal masses workup and to rule out renal calcifications and stones.
CT Anatomy
Cortico-medullary differentiation phase : In this phase difference in enhancement between renal cortex and medulla can be as much as 100 HU while in nephrographic phase the kidneys appear as a homogenous uniform nephrogram . The addition of the delayed phase is particularly useful if unenhanced scan has not been performed, with the advent of multidetector CT multiplanar reconstruction in the excretory phase allow evaluation of the collecting system including the renal pelvis,ureters and bladder (32)
B . Ureter
The normal ureter can be identified in non enhanced CT scan, although it is easier to identify if it contains contrast medium . It is visible medial to the lower pole of the kidney, anterior to psoas . More distally ; the ureter remains anterior to the psoas muscle and is lateral to the great vessels Having crossed the bifurcation of the common iliac artery, the ureter in the pelvis is medial