CASE REVIEW )
BY Prof Dr. Ahmed Al_Gebaly 20 YO Male Patient was admitted to the emergency ward with three-day history of left lumbar pain. Physical examination revealed a low-grade fever and tenderness and defense with left lumbar localization; laboratory findings revealed a leukocytosis. Routine US examination hepatomegaly
Epiploic appendages
Epiploic appendages (or appendix epiploica, plural: appendices epiploicae) are peritoneum-lined protrusions of subserosal fat that arise from the surface of the large bowel. Epiploic appendages typically measure 1.5 x 3.5 cm but have been reported to measure up to 15 cm in length 4. There are between 50-100 of them in the large bowel and extend from the caecum (where they may be absent) to the rectosigmoid junction. They are distributed longitudinally in two rows on the medial (along the taenia libera) and the posterolateral (along the taenia omentalis) aspects of the large bowel. There is only one row of appendices epiplicoae along the transverse colon and there are none along the rectum. Not normally visible on fluoroscopy, radiography or CT unless they are surrounded by contrasting material (e.g. contrast medium from HSG, haemoperitoneum or ascites) Multiple echogenic protrusions are noted from colonic wall - epiploic appendages. gross ascites. Normal epiploic appendages are easily seen with gross ascites.
number 50-100 and are distributed along the large bowel with variable frequency number 50-100 and are distributed along the large bowel with variable frequency rectosigmoid junction: 57% ileocecal region: 26% ascending colon: 9% transverse colon: 6% descending colon: 2% Epiploic appendagitis is a self limiting disease, and thus correct identification on CT prevents unnecessary surgery 2. Although it sometimes mimics acute abdominal diseases for which surgery is required, treatment options for epiploic appendagitis often do not include surgery; it usually reponds well to NSAIDs. Epiploic appendagitis
Epiploic appendagitis is a rare self limiting inflammatory/ischaemic process involving an appendix epiploica of the colon, and may either be primary or secondary to adjacent pathology. This article pertains to primary (spontaneous) epiploic appendagitis. The term along with omental infarction is grouped under the broader umbrella term intraperitoneal focal fat infarction nd This condition usually affects patients in their 2 to 5th decades with a predilection for women and obese individuals, presumably due to larger appendages although an uncommon condition, it accounts for up to 7% of cases of suspected diverticulitis 1. Since there is focal peritoneal irritation, pain maybe more localized than in the other causes of acute abdominal pain. Epiploic appendagitis merely denotes inflammation of the one or more appendages epiploicae, which number 50-100 and are distributed along the large bowel The pathogenesis is thought to be due to torsion of a large and pedunculated appendage epiploicae, or spontaneous thrombosis of the venous outflow, resulting in ischaemia and necrosis CT appearances are usually characteristic consisting of: a fat-density ovoid structure adjacent to colon, usually 1.5- 3.5cm in diameter 2 5-6 thin high-density rim (1-3mm thick) surrounding inflammatory fat stranding, and thickening of the adjacent peritoneum central hyperdense dot (representing the thrombosed vascular pedicle) 6 Chronically, an infarcted appendage epiploica may calcify, and may detach to form an intraperitoneal loose body. It may rarely involve the vermiform appendix epiploic appendages as so called epiploic appendagitis of the vermiform appendix 8, mimicking appendicitis both clinically and potentially on CT.
Mass lesion with fat density with a hyperdense rim, anterior to the descending colon with a hyperdense rim and surrounding stranding. (Epiploic appendagitis) 36 YO Male ; LIF pain, tenderness, guarding. At the junction of the descending colon and sigmoid colon there is a small ovoid fat-density structure with a thin enhancing rim and surrounding inflammatory stranding. This appearance is consistent with epiploic appendagitis. No diverticula are seen in the colon and given the young age of the patient, diverticulitis is unlikely. Findings are consistent with epiploic appendagitis. Surgical clips the inguinal regions bilaterally suggest previous bilateral hernia repair.
CT scan with poor contrast opacification demonstrates a fat-density ovoid mass with surrounding inflammatory stranding in the left iliac fossa. It abuts the sigmoid colon. No free fluid or free gas visible. This case demonstrates the classical appearance of epiploic appendagitis. It is an important diagnosis to make as it avoids unnecessary surgery. An epiploic appendage is seen as a rounded fat density structure (yellow dotted line) with extensive surrounding stranding. Centrally a dot is present (green arrow) representing the thrombosed vascular pedicle.
Alcoholic fatty liver disease
Almost all patients with alcohol abuse have an increased deposit of fat in the liver. The main purpose of imaging is to stage the disease and to recognize other conditions associated with alcohol abuse. Liver biopsy is the main tool for diagnosis and is considered the gold standard for diagnosis. it is not recommended to perform a biopsy for diagnostic purposes only. In some cases, the appearance of focal steatosis is problematic, as it presents like a hyperechoic nodule,or even like a ring-shaped lesion,mimicking liver metastases.
NAFLD (nonalcoholic fatty liver disease)
Fatty liver was observed in patients without alcohol abuse, especially patients with diabetes mellitus and overweight persons, but this has not produced any special interest for a long time.
It is now considered as a significant form of chronic liver disease.
NAFLD represents a broad spectrum of pathological conditions ranging from simple steatosis to steatohepatitis (NASH), advanced fibrosis and cirrhosis with the risk of hepatocellular carcinoma.
The prevalence of NAFLD is high, reaching 20% of the population. Conversely, prevalence of NASH is much lower but remains at a 2%. NASH is related to obesity, type 2 diabetes, hyperlipidemia, and anorexia nervosa
In up to one-third of patients, NASH might lead to cirrhosis simple steatosis
NAFLD encompasses two different entities, one a usual and benign condition, requiring no special treatment, the other a potentially severe liver disease that should be carefully staged and treated.
in most cases, simple steatosis, also called nonprogressive NAFLD, does not appear to be evolutive and requires no special attention in itself.
Pathologists see it in approx. 25% of all otherwise healthy adults. It can develop within a few weeks and can also disappear within such a time frame.
chemotherapy can lead to this effect
Diffuse hepatic diseases?!!
.Fatty liver .Cirrhosis .Storage diseases Fatty liver disease (steatosis)
Accumulation of lipid within cells is a pathologic process. Any type of lipid can accumulate within cells, such as cholesterol, triglycerides, and phospholipids. Fatty liver disease (steatosis) is characterized by accumulation of triglycerides within hepatocytes
Normally, free fatty acids are taken up by the hepatocytes and then converted into cholesterol esters, triglycerides, keton bodies, or phospholipids.
The image-based diagnosis of fatty liver usually is straightforward, but fat accumulation may be manifested with unusual structural patterns that mimic neoplastic, inflammatory, or vascular conditions Liver steatosis can result from either excess delivery of free fatty acids into the liver (e.g., diabetes mellitus), increased formation of lipids within the liver (e.g., alcohol ingestion), hepatocytes disease (e.g., hepatitis), or decreased formation of VLDL by the liver (e.g., protein malnutrition) Steatosis may progress to steatohepatitis ( with inflammation, cell injury, or fibrosis accompanying steatosis) and cirrhosis
Prevalence of Fatty Liver
General population about 15%.
Higher in 40% of consume large quanities of alcohol (>60g /day)
50% of Hyperlipidemia 75% of Obesity (BMI> 30 kg/m2) 95% of Both obesity and high alcohol consumption Types of Liver Steatosis
Diffuse fatty infiltration : the liver is usually enlarged with uniform decrease in density in the liver scan.
Focal fatty infiltration (The term fatty liver is more accurate) : there is an area of the liver that shows fatty infiltration while the rest of the liver is normal. It usually occurs in the same areas that are supplied by the third inflow systemic veins (from paraumbilical systemic veins): (porta hepatic, around ligamentum teres, and adjacent to gallbladder). It is seen most commonly in the left lobe of the liver. Focal Deposition and Focal Sparing
focal fat deposition or focal fat sparing characteristically occurs in specific areas:
Adjacent to the falciform ligament In the porta hepatis In the gallbladder fossa Focal fat deposition adjacent to insulinoma metastases, probably due to local insulin effects on hepatocyte triglyceride synthesis and accumulation. Focal fatty liver anterior to the portal vein
Preservation of the normal vasculature
Multiple fatty infiltrations : there are scattered low- density areas within a normal density liver. This type can be easily mistaken with metastases on noncontrast-enhanced liver CT scan.
Focal sparring : there are areas of normal liver parenchyma surrounded by large areas of low- density diffuse fatty infiltration
Focal fatty liver with multiple hyperechoic lesions that could mimic hemangiomas or metastases Segmental fatty infiltration/ steatosis and focal sparing/non steatosis
US Fatty liver (, fatty liver should not be considered present if only one or two of these criteria are fulfilled) • Liver echogenicity exceeds that of renal cortex and spleen • Poor delineation of the intrahepatic architecture • Loss of definition of diaphragm It is grossly true that a highly reflective liver is a commonly associated with a high degree of fatty infiltration. Signs on US
Fatty liver is visualized as highly echogenic liver. The high liver echogenicity can be compared to the echogenicity of the right renal cortex, which will show marked deference in echogenicity.
Focal fatty infiltration is seen as a focal, highly echogenic area within a relatively isoechoic (normal) liver parenchyma.
Focal sparring is seen as a focal area which is relatively hypoechoic (normal) within a highly echogenic liver. Signs on CT Hepatic steatosis is detected as diffuse or focal reduction of the liver normal density on noncontrast-enhanced scan. The normal liver density is 8 HU (Hounsfield unit)
When the amount of fat is significant, the average density is lower. In very severe cases, the liver density might be near 0 Hounsfield units (HU), similar to water density, or even negative. It is very unusual that the liver density is lower than 10 HU.
above that of the spleen (60 HU). Fatty liver density is 10 HU below spleen density on noncontrast-enhanced scan (if the normal spleen is 52 HU, then the fatty liver is <40 HU).
• Diffuse Fatty Infiltration Seen on CT. CT reveals the density of the enhanced liver parenchyma (L) to be significantly less than the density of the enhanced splenic parenchyma (S). Portal (p) and hepatic (h) veins run their normal courses without displacement or distortion
• Unenhanced CT • Attenuation of the liver is at least 10 HU less than that of the spleen • or attenuation of fatty liver is less than 40 HU • In severe cases, intrahepatic vessels may appear hyperattenuated relative to fat-containing liver tissue
On noncontrast CT images of the liver the vessels appear brighter than the hepatic parenchyma. Normally it is just the other way round. This is a typical finding in fatty liver Focal fatty infiltration is seen as a hypodense area with nonspherical margins (metastases usually have round edge).
The hypodense area or the mass does not show mass effect over the parenchyma around it,
In both focal sparring and focal fatty infiltration, hepatic vessels course within the fatty infiltration or focal sparring undisturbed. In contrast, metastases or other hepatic lesions will be cut off the hepatic vessels when they reach them. Normal versus fatty liver attenuation
• At enhanced CT, the comparison of liver and spleen attenuation value is not reliable.
• Fatty liver can be diagnosed at contrast- enhanced CT if absolute attenuation is less than 40 HU, but this threshold has limited sensitivity MR : Fatty liver The signal intensity of the normal liver parenchyma is similar on in-phase and opposed- phase images
The signal intensity loss on opposed-phase images in comparison with in-phase images.
Liver steatosis is diagnosed on MRI when the liver intensity drops to >30% deference on both T1W in-phase and T1W out-of-phase images
Accuracy for Detection and Grading of Fat Deposition
Sensitivity Specificity
US 60-100% 77-95%
NECT 43-95% 90%
Chemical shift GRE MRI 81% 100% Axial precontrast ( a ) and postcontrast ( b ) abdominal CT images show diffuse hepatic steatosis. Notice the density of the liver compared to the spleen in pre- and postcontrast images Diffuse lower density of liver compared to spleen MR
Initial reports had stated that MRI could show fatty deposition as hyperintense on T1-weighted images and T2- weighted images [15]. Clues were also a lack of a mass effect, vessels traversing the area with no distortion.
The most sensitive MR method for detecting liver fat deposition in liver cells is the combination of in phase (IP) and opposed phase (OP) sequences. This sequence is a regular T1-weighted gradient echo sequence. On OP images, the final signal is a subtraction of the fat signal from the water signal, voxel by voxel.
FOCAL FAT
Diagnostic confusion with tumors Common sites Periportal region of the medial segment of left lobe (segment IV) Either side of falciform ligament Cranial aspect of GB fossa
Characteristic features: Geographic appearance Lack of mass effect Vessels through the lesion US
Mostly seen in periportal region next to GB or lig. Trias
- Elliptical or triangular
- May occasionally show a patchy or flame like distribution in the liver Focal Deposition and Focal Sparing
Diffuse fat accumulation with focal sparing at US and CT. Fatty Infiltration With Focal Sparing. A. US image demonstrates a focal hypoechoic area of normal liver (NL) near the portal vein (p) in a liver (FL) that is diffusely increased in echogenicity because of fatty infiltration. B. CT image obtained without contrast enhancement demonstrates the spared area of normal liver (arrow) to be high density compared to the lower density of the fatty replaced liver (FL). Note the characteristic “flip-flop†appearance of fat density between CT and US. S, spleen. Normal Liver The signal intensity of the normal liver parenchyma is similar on in-phase and opposed- phase images
Chemical shift gradient-echo(GRE) imaging with in-phase and opposed-phase Axial T1W in- phase ( a ) and T1W out- of-phase ( b ) MRI in a patient with liver steatosis shows drop in the liver signal intensity >44% in the T1W out-of-phase image ( b ), diagnostic of hepatic steatosis Fatty liver The signal intensity loss on opposed- phase images in comparison with in-phase images.
Chemical shift gradient-echo(GRE) imaging with in-phase and opposed-phase Perivascular Deposition
Indicative of the diagnosis
An unequivocal signal intensity loss on opposed-phase images in comparison with that on in-phase images. The lack of a mass effect on the surrounded vessels are. The pathogenesis of perivascular fat deposition in the liver is unknown.
Perivascular Deposition
Subcapsular Deposition
In patients with renal failure and insulin- dependent diabetes, insulin may be added to the peritoneal dialysate during kidney dialysis. This route of insulin administration exposes subcapsular hepatocytes to a higher concentration of insulin than that to which the remainder of the liver is exposed. Administration of insulin results in a subcapsular pattern of fat deposition, which may be manifested as discrete fat nodules or a confluent peripheral region of fat. Subcapsular fatty liver deposition. a Axial contrast-enhanced portal phase CT image in a 58-year-old man with a neuro-endocrine tumour of the pancreas shows two small hypodense subcapsular hepatic lesions in segment V. MRI, b axial T1-weighted in-phase and c out-of-phase images show a drop of signal within the two subcapsular lesions on the opposed-phase image
hepatomegaly Azygos continuation of the IVC (het-erotaxia syndrome) in a 58-year-old man. CT image shows an abnormally dilated azygos vein (arrow) within the RCS in association with polysplenia (*). Abdominal CT after the administration of IVC. Axial cut showing the dilated hemiazygos vein (red arrow) to the left and posterior to the aorta, absence of the hepatic segment of the inferior vena cava continuing into the hemiazygos vein. Enlarged azygos- hemiazygos venous horacoabdominal CT after the administration of IVC. Axial cut of a patient with situs showing agenesis of the hepatic segment of the inferior vena cava continuing into the azygous vein, located to the left of the aorta. Absence of the infra- and intrahepatic portions of the IVC with azygos continuation in a 34-year-old woman. Contrast-enhanced CT image shows enlarged azygos and hemiazygos veins (straight arrows) with multiple venous collaterals (curved arrow). CECT in patient with polysplenia shows situs ambiguous, absent IVC, azygous continuation of the IVC Situs Solitus: Normal arrangement. Situs Inversus: Mirror image of situs solitus. Heterotaxy (aka Situs Ambiguous): any arrangement of internal organs other than situs solitus or situs inversus. Include: right isomerism or asplenia syndrome left isomerism or polysplenia syndrome. SITUS SOLITUS WITH DEXTROCARDIA the Latin situs, which means position, and solitus, which means customary. Thus, situs solitus signifies the customary, or normal, asymmetrical arrangement of the viscerovascular anatomy Situs inversus is the mirror image of situs solitus in toto. Although this condition is embryologically related to other situs anomalies, situs inversus must be strictly differentiated, because it has significantly different pathophysiologic and clinical implications. All other conditions occur in a spectrum called situs ambiguus. Patients with situs ambiguus tend to be grouped with those in whom right- or left-sided structures predominate (asplenia and polysplenia). Patients with right-sided symmetry typically lack a spleen, whereas patients with left-sided symmetry typically have a segmented spleen or multiple splenules. However, situs ambiguus, also called heterotaxia, occurs in a continuum; this is acknowledged in the classification of polyasplenia syndrome. the cardiologist applying the concept of segmental classification of cardiac anomalies, situs refers to atrial morphology. The pulmonologist is likely to assess lung lobation and bronchovascular anatomy. The gastroenterologist may focus on the presence or absence of the spleen Situs solitus. This is the usual arrangement of organs and vessels. The morphologic right atrium (RA), superior vena cava (SVC) and inferior vena cava (IVC),
Situs inversus (also called situs inversus totalis) is the ―mirror image‖ of situs solitus. Situs inversus is characterized by a two-lobed right lung with a hyparterial bronchus and three-lobed left lung with eparterial bronchus (i.e., the morphologic left lung is right sided and the morphologic right lung is left sided), left-sided liver, and right- sided spleen. There is usually an L-ventricular loop with the anatomic right ventricle positioned to the left of the left ventricle. The cardiac apex and stomach are right sided Situs inversus
is a mirror image of the situs solitus, occuring in about 0.01% of the population.
It presents with congenital cardiac anomalies in 3- 5%, with atrioventricular discordance and transposition of the great vessels being the most frequent alterations.
Another frequent association of situs inversus is the respiratory involvement in the Kartagener syndrome occuring in 20%.
Situs ambiguous results in the heterotaxy syndromes where one half of the abdomen and thorax are duplicated and "flipped" to represent the contralateral half resulting in symmetric morphology of normally assymmetric structures. This is called "isomerism". There are two syndromes which are associated with heterotaxy syndromes: polysplenia and asplenia syndromes. Polysplenia syndrome occurs with bilateral left-sidedness ("left isomerism").: characterized by duplication of the left sided structures including bilateral bilobed lungs with hyparterial bronchi (two morphologic left lungs) and multiple spleens. Both atria can represent morphologic left atria. There can also be azygous continuation of the inferior vena cava, atrial septal defects, partial anomolous pulmonary venous return and endocardial cushion defects. Asplenia syndrome occurs with bilateral right-sidedness ("right isomerism").: (also known as Ivemark's syndrome) is characterized by duplication of right-sided structures and absence of the spleen. There are bilateral trilobed lungs containing eparterial bronchi and both atria are morphologic right atria. The liver is symmetric and transverse and the stomach is also near the midline. There can also be common atrioventricular canal, univentricular heart, transposition of the great arteries, and total anomalous pulmonary venous return. Due to the immune problems associated with an absent spleen and the complex cardiac problems the mortality rate is up to 80% in the first year. The terms "hyparterial" and "epartieral" are used to communicate the relationship between the bronchus with the pulmonary artery using the bronchus as the reference point. "Hyp" is Latin for "low" or "beneath". "Ep" is Latin for "above". Remember that when using these terms they use the bronchus as the reference point.
Heterotaxy with polyesplenia
In Heterotaxy with polyesplenia the most frequent anomaly is the interruption of the inferior vena cava with continuation through the azygos vein or the hemiazygos associated with a short intrahepatic course of the IVC. In plain radiography, this can be seen as an absence of the normal IVC silhouette in the lateral projection in the posteroinferior border of the heart. Also, a prominent azygos vein in the PA projection is found. Multiple small spleens or more rarely, a lobulated spleen are found usually located proximal to the stomach (frequently along the greater curvature) due to its dorsal mesogastric embryologic origin. They can be in the left or right hypochondrium. In this group cardiac malformations are milder and less common. Usually associated with left isomerism: bilobar lungs with hyparterial bronchi (long bronchi running inferiorly to the pulmonary artery branches). In both Asplenia and Polyesplenia groups, the presence of a bridge liver is a common feature but is more common in the Asplenia type. Intestinal malrotation is a common feature in both asplenia and polyesplenia types of Heterotaxy syndrome.
Heterotaxy syndrome with Asplenia:
In this group a congenital absence of the spleen is found, causing a severe immunologic disorder. It is known a strong association with the presence of right isomerism: both lungs are trilobar with bilateral minor fissures and eparterial bronchi, meaning that both main bronchi are short and located superiorly to the pulmonary artery branches. Patients with asplenia usually have severe cardiac malformations associated, so only few of them reach the adult age. The most common malformations are common atrioventricular channel, univentricular heart and transposition of great vessels. All of them present with anomaly of the pulmonary drainage. In both Asplenia and Polyesplenia groups, the presence of a bridge liver is a common feature but is more common in the Asplenia type. Intestinal malrotation is a common feature in both asplenia and polyesplenia types of Heterotaxy syndrome.
In a situs solitus person (ie. the "normal" positioning of anatomic structures) the relationship between the right mainstem bronchus with the right main pulmonary artery is termed a right eparterial mainstem bronchus (ie. the right mainstem bronchus is above the right main pulmonary artery). The relationship on the left side would be a left hyparterial mainstem bronchus (ie. the left mainstem bronchus is below the left main pulmonary artery). the terms eparterial/hyparterial are being used the reference is to the mainstem bronchi and the main pulmonary arteries. Hyparterial left mainstem bronchus: refers to those bronchi which pass below the pulmonary arteries Eparterial bronchus: refers to those bronchi which pass above the pulmonary arteries Right isomerism is bilateral right sidedness with asplenia and bilateral eparterial mainstem bronchi. Left isomerism is bilateral left sideness with polysplenia and bilateral hyparterial mainstem bronchi
In situs solitus, the heart apex, spleen, stomach, aorta, and bi-lobed lung lay to the left of midline; the tri- lobed lung, gallbladder, liver, and inferior vena cava lay to the right. In situs inversus, these organs are located the exact opposite of the normal asymmetry. Both situs inversus and situs solitus are orderly arrangements of the viscerovascular structures of the body that are delineated during embryogenesis. In situs ambiguous, otherwise known as heterotaxy syndrome, the arrangement of organs within the body is disorderly. Patients with situs ambiguous traditionally have been categorized based on the number of spleens. Those with polysplenia typically are associated with hyparterial pulmonary bronchi, while asplenic patients usually have eparterial bronchi. Several overlapping anatomical abnormalities are found in both of these entities Asplenic patients have a higher incidence of congenital heart disease with serious cardiac manifestations. This typically leads to earlier presentation and detection. In contrast, there have been reports, as in this case, of asymptomatic patients with polysplenia diagnosed later in life. Cardiac anomalies in the heterotaxy syndrome occur during embryogenesis. Common morphologic abnormalities include atrial septal defects, ventricular septal defects, and bilateral superior vena cava. In polysplenia patients, the inferior vena cava is commonly discontinuous with the atrium. Venous return is via the left-sided azygous or occasionally hemi-azygous vessels, as seen in this case. In comparison, the asplenic grouping usually has normal venous drainage via the IVC Other manifestations associated with the polysplenic group include bilateral bi-lobed lungs, a midline liver, variable stomach location, and hyparterial bronchi In asplenia, findings typically include bilateral tri-lobed lungs, eparterial bronchii and, occasionally, ipsilateral location of the aorta and inferior vena cava. Situs solitus: The systemic atrium is on the right with a right- sided trilobed lung, liver, gall bladder, and inferior vena cava. The pulmonary atrium is on the left with a left-sided bilobed lung,stomach, single spleen and aorta. The cardiac apex is on the left. The incidence of congenital heart disease in patient with situs solitus and levocardia is 0.6%-0.8%. Situs inversus: Anatomic arrangement that is mirror image of situs solitus. The incidence of congenital heart disease is 3%- 5%. Situs ambiguous or heterotaxy: Refers to visceral malposition and dysmorphism associated with indeterminate atrial arrangement.Subclassified into apslenia syndrome-double right-sidedness, right isomerism, or Ivemark syndrome. Polysplenia or double left sidedness or left isomerism. The incidence of congenital heart disease inpatients with heterotaxy is very high, ranging from 50% to nearly 100%.
―Heterotaxy‖ is simply defined as an abnormality of situs where the internal thoracic and abdominal organs show an arrangement other than situs solitus or inversus. The term is synonymous with ―situs ambiguous. It is associated with a spectrum of cardiac malformations varying from relatively simple anomalies to very complex defects. The morphologic spectrum of the heterotaxy syndrome includes atrial isomerism, abnormal thoracic and abdominal visceral situs (in particular the presence or absence of the spleen), anomalous systemic or pulmonary venous return, and associated cardiac defects
Atrial Isomerism The atria maintain their laterality throughout development; hence, they define the cardiac situs. In normal individuals, the morphologic right atrium is on the same side as the morphologic right-sided thoracic and visceral structures. Likewise, the morphologic left atrium is on the same side as the morphologic left-sided thoracic and abdominal structures. At imaging, the atria can be recognized by their different anatomy (described in detail in Sect. 1.2). Briefly, the right atrium is the more trabeculated atrium with the broad-based appendage and receives blood from the vena cava. The left atrium has a smaller, narrower appendage and receives blood from the pulmonary veins Atrial isomerism refers to hearts with bilaterally right or bilaterally left atrial appendages [4–6]. Right atrial isomerism is characterized by the presence of a morphologic right atrium on both the right and left sides of the midline (Fig. 20.2). Likewise, left atrial isomerism is characterized by morphologically bilateral left atria (Fig. 20.3). Although atrial isomerism is often present in heterotaxy syndrome, it is not a reliable term to describe the syndrome because it inaccurately reflects the full constellation of abnormalities. Atrial appendage morphology. Panels (a) and (b) are two axial computed tomography images. The right atrial appendage (RAA) is a blunt, broad-based structure lined with pectinate muscles that form a trabeculated surface. The left atrial appendage (LAA) is smaller and narrower and has a more restricted junction with the left atrium (LA). Ao aorta Left atrial isomerism. The atrial appendages (AA) bilaterally are elongated and fingerlike, consistent with left atrial morphology. RVOT right ventricular outflow tract Patient with right-sided polyesplenia (arrows). There is minor fissures in both lungs (yellow arrows), being trilobated (right isomerism). There is also basal bronchiectasis (red arrow). Patient with dextrocardia and interruption of IVC with Azygos vein continuation. The PA projection shows a prominent Azygos (blue arrows) and the lateral projection shows the absence of the IVC silhouette (yellow arrowhead). Variability of the liver arrangement. In figures a and b the liver has a bridge configuration with left polyesplenia. In figure c there is also a bridge liver but with right polyesplenia. In figure d the liver is left sided. Patient with right sided polyesplenia with the stomach in the right side and intestinal malrotation: all the colon is located in the left hemiabdomen (blue arrows) while the small intestine is in the right hemiabdomen (red arrows). Polyesplenia with intestinal malrotation: the colon is completely right sided (blue arrows) and the small intestine is on the left side (red arrows). If the atria are not distinguishable based on morphology, then determination of atrial situs can be made based on localization of noncardiac structures, namely, the tracheobronchial tree morphology (i.e., tracheobronchial situs). The right superior branch of the right main bronchus is eparterial, meaning that it is located above the segmental pulmonary artery that supplies the superior lobe of the right lung. The left superior bronchus is hyparterial and passes below the pulmonary arteries. The right, middle, and inferior lobar bronchi and left inferior lobar bronchus are also hyparterial, passing below the arteries. In right isomerism both bronchi are eparterial (Fig. 20.4), and in left isomerism, both bronchi are hyparterial Right isomerism. Both bronchi (arrows) are eparterial and course above the pulmonary arteries (PA)
Left isomerism. Both bronchi (arrows) are hyparterial and course below the pulmonary arteries (PA) Heterotaxy — Heterotaxy, derived from Greek (hetero, meaning "different," and taxy, meaning "arrangement"), is also referred to as visceral heterotaxy or heterotaxy syndrome. It is defined as an abnormal arrangement of the internal thoracic- abdominal organs across the left-right axis of the body. Patients with heterotaxy have been historically stratified into either the subsets of asplenia syndrome or polysplenia syndrome. However, this classification is not useful in describing the cardiac malformations associated with heterotaxy. No single examination is best for the evaluation of heterotaxy. Frequently, the initial examination performed in patients with this condition is plain chest radiography, which is often performed in patients with suspected congenital heart disease. Historically, the diagnosis often depends on the angiographic findings in the cardiac and abdominal structures or on the results of abdominal examination via an iatrogenic pneumoperitoneum. However, ultrasonography, computed tomography (CT) scanning, and magnetic resonance imaging (MRI) are all useful in assessing the various viscerovascular abnormalities in patients with heterotaxy MRI is particularly useful, because it can also delineate cardiac defects. Plain radiographs can be helpful in delineating an abnormal visceroatrial situs. A midline heart and liver, with a midline or right-sided stomach, and symmetrical bronchial branching are diagnostic findings.
In many patients with situs ambiguus, radiographs provide the initial clues to the diagnosis, which should be made in patients with a midline liver, in those with a right-sided or midline stomach, and in patients with mesocardia or dextrocardia
However, many patients with situs ambiguus do not have any of these findings, and plain radiographic findings may erroneously suggest situs solitus or situs inversus totalis. When identified, bilateral eparterial bronchi (bronchus above the artery, as in a typical right hilum) are suggestive, but not diagnostic, of asplenia, whereas bilateral hyparterial bronchi (bronchus underneath the artery, as in a typical left hilum), seen in the image below, are suggestive, but not diagnostic, of polysplenia
The laterality of the aortic arch is relatively unhelpful because a right-sided aortic arch occurs frequently in situs solitus, and the arch may be either right- or left- sided in situs ambiguus. A right-sided aortic arch is most frequently encountered in patients with situs solitus. Typically, it indicates congenital heart disease, particularly tetralogy and truncus arteriosus, Interruption of the inferior vena cava with azygous continuation should suggest situs ambiguus, particularly polysplenia. However, this finding is not specific
CT scanning may be helpful in delineating viscerovascular abnormalities in patients with heterotaxy and in determining whether they should be grouped with patients who have asplenia and a right-sided tendency or with those who have polysplenia and a left-sided tendency
An abnormal bronchial situs is highly likely in patients with these conditions; bilateral eparterial bronchi suggest asplenia, whereas bilateral hyparterial bronchi suggest polysplenia
Bilateral superior vena cavae are often present, or a single vena cava may be present on the right or left side. Malseptation of the cardiac chambers may be seen with contrast enhancement.
Splenules are highly variable and may consist of multiple small structures, a few small structures, or a large or lobulated spleen. Lack of any splenic tissue and the absence of a splenic artery and vein indicate asplenia. Situs solitus with dextrocardia
dextrocardia (a right thoracic heart), the ascending aorta and aortic knuckle are normally located, the descending aorta runs its normal course the right hemidiaphragm is lower than the left hemidiaphragm a right-sided liver (L), a left-sided stomach (St) and a left-sided spleen (S) situs inversus
Classified to: situs inversus with dextrocardia (also termed situs inversus totalis) situs inversus with levocardia, an extremely rare variant of situs inversus, almost always associated with congenital heart disease Situs inversus in a 46–year-old man. Axial CT images of the abdomen demonstrate mirror-image location of the abdominal structures. Note left-sided inferior vena cava (IVC) KARTAGENER´S SYNDROME
Dyskinetic cilia syndrome (DCS) is characterized by abnormal ciliary structure and movement, resulting in abnormal mucociliary clearance and chronic infection.
Bronchiectasis and sinusitis are common manifestations.
About half of patients with DCS also have situs inversus.
The combination of bronchiectasis, sinusitis and situs inversus is called Kartagener´s syndrome. It is present in 20% of all patients with situs inversus.
Cylindrical bronchiectasis are most common Primary Ciliary Dyskinesia (PCD)
Umbrella term for genetic disorders affecting proteins responsible for the structure and/or function of motile (moving) cilia.
1933 Manes Kartagener (Swiss pediatrician) published a report of 4 children with bronchiectasis, sinusitis and situs inversus. The syndrome is named ―Kartagener Syndrome.‖
1975 Afzelius (Swedish ultrastructuralist) and Pedersen (Denmark) independently hypothesize that ―immotile cilia‖ may be the underlying cause and the syndrome is renamed ―immotile cilia syndrome.‖
1981 Based on new understanding of cilia pathogenesis, Sleigh suggests a name change to ―primary ciliary dyskinesia‖ Three Types of Cilia in Human Cells:
Nodal (specialized organelle appearing once only on the embryonic node)
Primary (non-motile chemosensory monocilia)
. Motile
. Upper & lower respiratory tract
. Eustachian tube of middle ear
. Ependymal lining of the ventricles of the brain
. Fallopian tubes of the female reproductive system
. Sperm tails (technically flagella, but structurally similar to cilia) Characteristic of PCD:
•Neonatal respiratory distress •Chronic rhinorrhea
•Situs anomalies
•Good nutritional status
•Otitis media/hearing loss •Bronchiectasis w/normal flora Clinical Consequences of PCD: Adults
. Neurogenic hearing loss may occur
. Fertility issues are a concern
. Bug profile gets nastier: NTM infections (20%), mucoid Pseudomonas and other gram-negatives more common.
. Bronchiectasis is universal
. Pulmonary functions are variable & don’t always correlate well to actual extent of lung disease and respiratory flora present
Kartagener’s syndrome: present in 20% of all patients with situs inversus situs inversus totalis (dextrocardia, right-sided aortic arch, left-sided liver Situs inversus in a 46–year-old man. Axial CT images show a right aortic arch (RAA) (A), a right-sided descending aorta (DA) (B) and reversal of the normal geographic cardiac chamber position (C). Lung window view shows mirror- image bronchial anatomy, with left-sided bronchus intermedius (BI) SITUS AMBIGUUS OR HETEROTAXY
often referred to as isomerism or heterotaxy syndromes
This is often associated with asplenia (Ivermark syndrome) and polysplenia, respectively. There may be levocardia, dextrocardia or mesocardia.
The IVC may be absent, or interrupted, with azygos or hemiazygos continuation of the infrarenal segment of the IVC, with drainage into the right or left superior vena cava. Anatomy in human heterotaxy. Situs solitus (SS). The cardiac apex is oriented leftward, the right lung is trilobed, the left bilobed, the liver is on the right, and the stomach and spleen are on the left.
SITUS AMBIGUUS WITH POLYSPLENIA
Situs ambiguus with polysplenia, often referred to as left isomerism or bilateral left-sidedness, is characterized by duplication of left-sided structures, with bilateral bilobed lungs, hyparterial bronchi and bilateral left atria.
Abnormalities of systemic venous drainage are common and include interruption of the intrahepatic IVC with azygos/hemiazygous continuation, duplication of the superior vena cava (SVC) and partial anomalous pulmonary venous return.
The multiple spleens are typically adjacent to the greater curvature of the stomach, which is usually right sided, but can be left sided Situs ambiguus with polysplenia and azygous continuation of IVC, Situs ambiguus with polysplenia and azygous continuation of IVC Situs ambiguus with polysplenia and azygous continuation of IVC, splenia syndrome is usually diagnosed in neonates. is a type of heterotaxy syndrome. most patients die before 1 year-old because of severe/complexe congenital heart disease. Most patients are immunocompromised due to absent spleen. Main characteristic radiographic features include: absence of spleen bilateral eparterial bronchi bilateral trilobed lungs bilateral right atria transverse liver
IVERMARK’S SYNDROME (asplenia), or bilateral right-sidedness, left sided organs are a mirror image or the normal right sided organs. This is also called right isomerism.
SITUS AMBIGUUS WITH ASPLENIA
characterized by an absent spleen and duplication of right-sided structures (bilateral right-sidedness),
Dextro-position of the heart, absent spleen, transverse liver, bilateral tri-lobed lungs.
Cardiac anomalies associated with asplenia are usually severe, are present at an early age, and have a poor prognosis.