Presentation on theme: "Imaging Diagnosis Of Parasitic Helminthes 2 Major Multi-System Diseases By Sh.Ghaffary January 2008."— Presentation transcript:
Imaging Diagnosis Of Parasitic Helminthes 2 Major Multi-System Diseases By Sh.Ghaffary January 2008
Major Multi-System Diseases Schistosomiasis Hydatid Disease Taeniasis, Cysticercosis Sparganosis
Schistosomiasis Acute Schistosomiasis ( The Katayama Syndrome) The chest radiograph is either normal or shows increased vascular and interstitial markings and minimal enlargement of the hilar lymph nodes. Miliary tuberculosis in its early stages or a simple virus infection may be suspected. The changes are not specific (history and eosinophilia). The chest radiograph returns to normal with or without treatment
Katayama stage of an acute S. haematobium infection. This young adult had not previously been exposed to schistosomiasis when he bathed in a Central African lake 4 weeks before this radiograph. The chest radiograph shows an increase in vascular markings with a faint nodular pattern throughtout both lungs; the hila are prominent. There were no focal lesions and the findings were transient.
Schistosomiasis Acute Schistosomiasis ( The Katayama Syndrome): In the abdomen there are three sonographic (and CT) findings which contribute to the diagnosis of the Katayama stage of acute schistosomiasis. 1. nonspecific hepatosplenomegaly. The left lobe of the liver may be more enlarged than the right. liver is sonographically homogeneous or, in a few cases, hyperechoic. 2. At the same time there may be periportal and juxtapancreatic lymphadenopathy, particularly in children. The lymph nodes are sharply outlined and round or oval, with a thin surrounding hypoechoic halo.
Schistosomiasis Acute Schistosomiasis ( The Katayama Syndrome): 3. Ultrasonography may also show multiple small nodules throughout the liver parenchyma. These nodules may persist in spite of adequate therapy: they may be 4-5 mm in diameter and are well shown on CT scanning, being hypodense with delayed contrast enhancement. ( In subacute schistosomiasis, echogenic lesions in the liver are thought to be due to portal vein branches (in cross-section). It probably takes from 3 to 5 years to develop stage one periportal (Symmers) fibrosis when patients have a high-intensity infection. With low infection rates, it may take much longer. There is no evidence of portal hypertension during the Katayama stage. )
Schistosomiasis Acute Schistosomiasis ( The Katayama Syndrome): The acute phase of S. japonicum infection results in CNS involvement in about 2% of patients. CT scans of the brain may show edema around low- density inflammatory foci, which are often multiple and contrast-enhancing with edema. In some cases there may be a mass effect, causing shift with pressure on any part of the ventricular system. (This pattern of CNS involvement must be distinguished from the mass effect which is found in chronic cerebral schistosomiasis affecting patients who have been previously and often repeatedly infected.)
Chronic Schistosomiasis Imaging changes other than in the acute state are different with each type of infection and will be discussed separately. The clinical and laboratory investigations for each patient depends on the symptoms.
Chronic Schistosomiasis All three major species of schistosome may affect the kidneys. Infection with S. mansoni, S. japonicum, and S. intercalatum particularly may affect the liver, causing cirrhosis, portal hypertension, and splenomegaly. Espohageal varices develop, with resulting hemorrhage, and pulmonary hypertension may be an added complication. In S. haematobium infection, as well as urinary tract involvement, there may be granulomatous disease of the colon; the latter often occurs in conjunction with mucosal polyps and causes diarrhea. In S. japonicum infection, the disease may affect the small bowel as well as the colon, liver, and lungs; cerebral infections may cause epilepsy.
Schistosomiasis Haematobium: When there is hematuria caused by S. haematobium, ultrasound and subsequently intravenous urography may be indicated. Cystoscopy may show multiple papillomas within the bladder. There is individual variation between populations, even villages, seemingly infected with the same schistosome to the same extent. Anyone working in a particular country or locality must determine the effect of schistosomiasis in their own patients, but it is possible to give a general review. Chronic Schistosomiasis
Schistosomiasis Haematobium: Ultrasonography In the urinary tract, ultrasonography can detect hypertrophy of the bladder mucosa, thickening of the bladder wall (which is normally less than 5 mm when the bladder is distended), and bladder calcification. If the ureters are easily demonstrated by ultrasound, they are probably thickened and abnormal; in some patients calcification will be seen, but ultrasound is not a reliable way to demonstrate early ureteric changes. Dilatation of the renal collecting system can be detected very early, and represents the result of significant ureteric dysfunction. Chronic Schistosomiasis
Schistosomiasis Haematobium: Radiography Plain radiography of the abdomen is of no assistance until calcification has developed in the bladder and ureters, although in severe infections calcified eggs may also be seen in the soft tissues. ( Early calcification is much more clearly seen by CT.) Intravenous (contrast) urography will provide very useful diagnostic information. All the early findings will be in the ureters and bladder; the kidneys remain normal until later in the disease.
Chronic Schistosomiasis Schistosomiasis Haematobium: Radiography changes in the ureters 1. persistent filling of the lower segment in all films of the urography series, not dilated or otherwise abnormal 2. Dilatation of the filled distal, intrapelvic segment 3. Earliest ureteric constriction is within the bladder wall 4. Changes in ureteric peristalsis 5. Ureter will have a ragged outline and a beaded internal appearance, with some irregular dilatation because of acute "pseudotubercles" in the submucosa. 6. As they heal these may cause strictures. In more advanced cases there are multiple strictures, and gross irregularity.
Intravenous urograms of two African men. Kidneys are normal, but both ureters are filled throughout their length and the lower thirds are dilated, irregular, and show beading due to multiple intrinsic constrictions. Their bladders do not show any calcification
C.In another patient there is narrowing of both ureters close to bladder and in the right ureter there is a segment of dilatation between two areas of stenosis. D. Persisitent filling in the lower half of both ureters, with a long constriction in the right ureter just above the bladder.
B: marked dilatation of left ureter, showing the typical narrowing as the ureter enters the bladder wall. The right ureter is not distended or even filled, so it may be normal C: Ascending urography in another patient shows stenosis of the distal segment of the left ureter within the bladder wall and marked dilatation above it.
Schistosomiasis Schistosomiasis Haematobium:Radiography Blader and renal changes 1. The bladder outline first becomes hazy and indistinct, due to submucosal edema and pseudotubercles. 2. As the granulomas become fibrotic, the bladder wall shows calcification, but the calcium is not within the fibrous tissue. rather, it is entirely submucosal, in the eggs. 3. As the calcification spreads up the ureter, there will be a matching reduction in the rate of peristalsis. 4. By the time there is hydronephrosis and hydroureter, renal function is decreased with marked dilatation of the whole system. 5. secondary infection will hasten these changes.
The ureters can calcify in schistosomiasis haematobium, with (or, rarely, without) bladder calcification. Calcified ureters may be narrowed or dilated
The heavily calcified (empty) bladder of an Egyptian male patient. Extremely heavy bladder calcifcation in schistosomiasis haematobium Gross bilateral hydronephrosis and hydroureter demonstrated by reflux from a retrograde cystogram. The ureters are atonic and have lost the beaded appearance.
multi-layered calcification of the entire bladder wall Ultrasound scans showing gross thickening of the bladder wall and of the ureter
Schistosomiasis Schistosomiasis Haematobium: Lungs Radiological abnormalities in the chest are uncommon in patients infected with S. haematobium 1. the Katayama syndrome. 2. reaction around the larvae. This is a local immune reaction similar to others in the Loeffler syndrome. There will be scattered hazy foci of consolidation in both lungs, changing in both size and position at short intervals, and without any specific distribution. There is no lymphadenopathy. 3. The third pattern is often found by chance in the elderly : a pattern of fine, generalized interstitial fibrosis, distributed equally throughout both lungs.
late stage of schistosomiasis. Both lungs show marked interstitial fibrosis and there is enlargement of the main pulmonary arteries. Pulmonary hypertension has many causes and there is no way to distinguish schistosomiasis, nor, at this stage, will specific therapy have any effect.
Chronic Schistosomiasis Schistosomiasis Haematobium: Colon S. haematobium can cause a granulomatous reaction in the large bowel. A Superficial ulceration and edema causing irregularity of the right half of the transverse colon Rectal and colonic calcification may be seen
Chronic Schistosomiasis Schistosomiasis Mansoni: The main imaging findings in S. mansoni infections reflect the pathological changes in the bowel, portal system, and lungs. Large Bowel Changes follow as: 1) An edematous mucosal pattern with tiny ulcers leading to spasm and incomplete distention.
there are many tiny punctate mucosal ulcerations, a double contrast barium enema will show a fine granular mucosa, as in this hepatic flexure
Chronic Schistosomiasis Schistosomiasis Mansoni Large Bowel (continue) 2) loss of haustration, chiefly in the descending and sigmoid colon, most marked in the distribution of the inferior mesenteric artery. 3) heavier infection and chronic exposure leads to multiple granulomatous polyps, usually 1-2 cm in diameter, especially in the rectum, sigmoid and descending colon. 4) Strictures may develop, and can be mistaken for carcinoma or Crohn's disease. 5) Calcification in the eggs may be seen
Schistosomal polyposis (arrows) extending from the rectum to the transverse colon (air-barium enema). Schistosomiasis Mansoni
A barium enema. a polypoid mass arising from the left lateral rectal wall in the frontal view (E), more clearly seen in the post evacuation film (F).
This barium enema shows stenosis of the rectum and a stricture in the midsigmoid colon. Throughout the rectosigmoid there is loss of haustral markings and the bowel has become tubular and rigid. Schistosomiasis Mansoni
S. mansoni does not commonly cause radiological changes in the small bowel. All varieties of schistosomiasis can affect the duodenum; patients present clinically with vague symptoms suggesting peptic ulceration. A) Marked deformity and narrowing of the pylorus and duodenum. B )The edematous second and third parts of the duodenum Schistosomiasis Mansoni: small bowel
Chronic Schistosomiasis Schistosomiasis Mansoni Biliary Tract and Pancreas: Tubular and irregular calcification may be seen in the main hepatic ducts, the common hepatic, cystic, and common bile ducts, and also the pancreatic duct. There is seldom ductal obstruction. The tubular calcification may be seen on plain radiographs, It is well shown by CT as calcified ring densities or, depending on the section, parallel tubular lines.
Schistosomiasis Mansoni: Biliary Tract and Pancreas heavy calcification in the common hepatic duct (arrows), cystic duct (open arrow), and pancreas (curved arrows). The CT scan showing dense calcification in the neck of the gallbladder (arrows)
Chronic Schistosomiasis Schistosomiasis japonica The radiological findings are different because eggs are smaller and more in number. The S. japonicum worms live in mesenteric veins and their eggs are deposited predominantly within small bowel venules and in the mesentery. Small Bowel: The mucosa of the duodenum and the upper jejunum becomes edematous, coarse and irregular; motility is decreased and there may be some dilatation. The terminal ileum may show similar changes.
Schistosomiasis japonica: Small Bowel Four views of the first and second part of the duodenum of a Chinese patient with schistsomiasis japonica.
Chronic Schistosomiasis Schistosomiasis japonica Colon and Rectum: Schistsoma japonicum infection produces changes very similar to those seen in schistosomiasis mansoni. Retroperitoneum Granulomas located in the retroperitoneal space may become large enough to resemble malignant disease. Although CT, and occasionally ultrasound, can demonstrate multiple eggs, the exact differential diagnosis may only be possible by biopsy.
Chronic Schistosomiasis Hepatic Schistosomiasis Hepatomegaly and an often massive splenomegaly is common wherever there is schistosomiasis. Periportal fibrosis occurs in any type of schistosomiasis. Changes in the liver : 1. thickening around the portal vein and its main branche 2. when portal hypertension develops, there is usually splenomegaly 3. multiple varicosities and collateral veins will develop.
Chronic Schistosomiasis Hepatic Schistosomiasis Schistosomiasis japonica may cause little clinical evidence of liver damage. In schistosomiasis japonica the eggs are frequently deposited along the fibrous septa of the liver with only a mild inflammatory response. The eggs are more common in the peripheral or subcapsular regions. The hepatic changes of schistosomiasis japonica are characteristic.The background picture of periportal fibrosis is similar to S. mansoni infections, but the extent of hepatic calcification is quite different
periportal fibrosis due to S. mansoni
Nonenhanced CT shows septal calcification close to the top of the liver, better seen with contrast enhancement S. japonica
Nonenhanced CT scan of a 79-year-old Japanese male with S. japonicum in his stool.
Hydatid Disease Hydatid cysts are classified into four types on the basis of their appearance : Type I: Simple Cyst with No Internal Architecture Type II: Cyst with Daughter Cyst(s) and Matrix Type III: Calcified Cyst Type IV: Complicated HC ultrasound, CT, or MRI provides the best images. All methods of scanning can provide images in multiple planes and no added contrast is necessary, except in CT imaging. Used alone, or in combination, an almost 100% positive diagnosis of hydatid disease can be made in the majority of cases. Imaging may even provide a strong diagnostic probability when immunodiagnosis is equivocal or even (rarely) inaccurate.
Hydatid Disease Sonography should be the first method used to scan the patient, with a chest radiograph added. sonography is highly accurate (except in the chest, skeleton and CNS). CT and MRI often provide additional valuable information. Pulmonary lesions are usually detected on the chest radiograph but, when it is available, CT is helpful Brain hydatids can be imaged by either CT or MRI Plain films are often adequate for imaging bone hydatids, but CT and MRI yield more information as to extent of the lesion and possible soft tissue involvement. Angiography, Doppler sonography and nuclear medicine are only occasionally useful in the diagnosis of cystic hydatid disease and are utilized only when the other modalities are unavailable.
Hydatid Disease Type I: Simple Cyst appear as a well-defined anechoic mass with or without hydatid sand and septa. Unilocular cysts are considered to be an initial stage in the development of the parasite. The pericyst is rarely identified by US and is seen by CT only if it is calcified. However, it is demonstrable by MRI, particularly on T2-weighted images which produce a low intensity rim. Neither the cyst nor the pericyst enhance by CT or MRI as they are avascular
Hydatid Disease Type I: Simple Cyst At CT, a type I hydatid cyst appears as a well-defined, water- attenuation mass. Frequently, the septa and cyst wall enhance after injection of contrast material at CT and MRI, a finding that helps differentiate type I hydatid cyst from a simple liver cyst. MRI features are also similar to those of a simple liver cyst and include hypointensity on T1-weighted images and marked hyperintensity on T2-weighted images. A low-signal-intensity rim ("rim sign"), which is more evident on T2 MRI, has been described as characteristic of hydatidosis as opposed to nonparasitic cysts in the liver and lungs. This finding represents the parasitic membranes and pericyst. However, it is a nonspecific finding that can also be seen in amebic abscess, hepatocellular carcinoma, and hematoma.
Hydatid Disease Type I lesions have a non-specific cystic appearance but if the patient is rotated immediately before US scanning the settling hydatid sand produces signals which have been likened to falling snow Ultrasound scan reveals echos at bottom of a liver hydatid caused by hydatid sand (arrows).
Univesicular uncomplicated type I cyst
Type I: Simple Cyst Incidentally found type I HCs in a 45-year-old woman. Computed tomographic (CT) scan shows multiple unilocular hypoattenuating lesions in the liver (maximum lesion diameter, 15 mm) and spleen (maximum lesion diameter, 30 mm).
MRI of a simple viable type I hydatid cyst of liver. (A) T1-weighted image (SE 733/20). Cyst wall is isointense relative to cyst contents. (B) T2-weighted image (SE 2000/100). Cyst wall, consisting of both intact parasitic membranes and pericyst, is of low signal intensity compared with high signal of cyst contents.
Large hypermature hydatid cyst filled with debris. Some detachment of the cyst wall from the host pericyst is noted Hydatid Disease
Type II: Cyst with Daughter Cyst(s) and Matrix Daughter cysts are seen inside the mother cyst. floating membranes or vesicles can also be seen in the cyst Sometimes multiple cysts and echogenic areas that are enclosed together within a single capsule give rise to a "racemose" or "wheel spoke" appearance. Consolidation of the daughter cysts may produce echogenic solid lesions. Type II lesions usually have a characteristic appearance due to daughter cysts whether or not fluid or matrix are present
Hydatid Disease Type II: Cyst with Daughter Cyst(s) and Matrix type II HCs can be visualized in three stages depending on the age, number, and arrangement of the daughter cysts: 1. Type IIA lesions contain round daughter cysts arranged at the periphery. 2. Type IIB lesions contain larger, irregularly shaped daughter cysts that occupy almost the entire volume of the mother cyst creating a "rosette" appearance 3. Type IIC lesions appear at CT as relatively high- attenuation round or oval masses with scattered calcifications and occasional daughter cysts. These findings represent the degeneration of old cyst
Multivesicular type II hydatid with multiple daughter cysts giving a septated appearance to the cyst
Type II hepatic cyst with peripheral calcification. Multiple round daughter cysts are seen peripherally within the lesion.
Old hypermature liver hydatid. Non-contrast CT shows calcification in the cyst wall and matrix and fluid within the cyst, suggesting it is still evolving and should be treated
Hydatid Disease Type III: Calcified Cyst: Type III lesions are dead cysts with total calcification. They demonstrate strong posterior shadowing at ultrasonography and manifest as round, hyperattenuating areas at CT and hypointense areas at MRI. Nonenhanced CT may show minimal or partial calcification of the rim of hydatid cysts This is important, because a segmentally calcified cyst may still harbor a living parasite and therefore may be infective. Total rim calcification suggests degeneration and the parasite is usually, but not invariably, dead (clinically, it can be observed rather than actively treated.) Discovery of a type III lesion should provoke a search for uncalcified type I and II cysts in the liver and other organs.
Hydatid Disease Type III: Calcified Cyst: Chest CT-scan demonstrating a calcified hydatid cyst on the dome of the liver
Two hydatid liver cysts in a 75-year-old man. The larger pseudotumoral cyst has some calcification in its wall while the smaller type III cyst is totally calcified on non- contrast CT.
Hydatid Disease Type IV: Complicated hydatid cyst: Complications include rupture and superinfection and may be seen in both type I and type II HCs. Contained rupture makes the detached endocyst visible by all cross-sectional imaging methods. The lesion does not become smaller. Communicating rupture also produces a characteristic separation of endocyst from pericyst, and the cyst becomes smaller.
Hydatid Disease Type IV: Complicated hydatid cyst: If cyst ruptures in to the biliary track ERCP shows filling defects within the biliary tree and may also reveal retrograde communication with the cyst cavity. Biliary obstruction, if it occurs, may result in dilatation of downstream ducts. occasionally daughter cysts or fragments of endocyst may be seen in the biliary tree by US, CT or MRI. Cysts may also rupture directly into pleural and peritoneal cavities. If air replaces some of the fluid in the pericyst cavity of lung lesions, the air meniscus and water lily signs are produced on upright chest radiographs Bacterial superinfection of HC is always secondary to rupture. Up to 25% of ruptured cysts may become infected. Numerous signs of cyst infection have been described, including poor delimitation, mixed internal echoes, and air-fluid or fluid-fluid levels. However, these signs can also be seen in both intact HC and ruptured, uninfected HC.
Communicating rupture of a type I liver hydatid. CT scan shows partial rupture through the slightly calcified anterior wall of the cyst into the surrounding hepatic parenchyma. The "floating membrane sign" produced by detachment of the germinal membranes of the endocyst is well demonstrated.
Rupture of a type IV hepatic cyst into the biliary tree in a 48-year-old man who presented with acute onset of jaundice and pain in the right upper quadrant. CT scan reveals a nonenhancing mass with irregular contours
Air meniscus in a pulmonary hydatid seen on CT cut.
The "sign of the double arch" or "cyst-within-a-cyst" appearance (arrows) in a ruptured pulmonary hydatid. Once rupture of the cyst begins, a large opening may develop in the membranes and the shrinking cyst expels part or all of its fluid into the communicating bronchus. At this stage, air may enter the endocyst, producing an air-fluid level within the cyst that may itself be capped with a crescent of air between the pericyst and endocyst. The wall of the endocyst appears as an arch above the air-fluid level and the surrounding pericyst is visible as a larger arch.
(A) MRI of liver hydatid with detached parasitic membranes on T-2 weighted image producing the "snake or serpent sign". Both detached parasitic membranes and pericyst are of low intensity. (B) MRI of another ruptured hepatic hydatid cyst showing the "snake or serpent sign" of detached membranes within the endocyst. The cyst wall (black arrows) is of low signal intensity relative to the cyst contents and the surrounding high-intensity host reaction and edema (white arrows).
Hydatid Disease Multisystem involvement Hydatid disease can occur almost any where in the body and demonstrates a variety of imaging features that vary according to growth stage, associated complications, and affected tissue. Radiologic findings range from purely cystic lesions to a completely solid appearance.
Hydatid disease in the lung 35 yr old farmer presented with a one week history of right sided pleuritic chest pain. Chest X-Ray revealed: A large 7cm cavity occupying right middle lobe. It contained fluid and air with an undulating, crenated interface. There was conslidation in the right middle lobe. A diagnosis of a ruptured hydatid cyst was made.
Hydatid disease in the lung single hydatid cyst in RLL. Clinical presentation: Male from the middle east, incidental finding. There is a well defined mass lesion, which lies in the right lower zone. The right hemidiaphragm margin is preserved. The right heart margin was visible in the original.
Hydatid disease in the lung water lilly sign : A 50 year old man from the Middle East with recent productive cough. There is a cavity in the right mid-zone. It has uniformly thick walls. The walls of the cavity have partly collapsed and are not under tension from the surrounding lung. There is a contained fluid level
Hydatid cyst in kidney Clinical presentation:Young adult male from the Middle-East with an abdominal mass. The IVU shows a large soft-tissue mass expanding the lower pole of the right kidney. The right pelvicalyceal system is tilted and displaced upward.
Type I HC of the brain Axial CT scan shows a mass in the left parietal lobe with an attenuation similar to that of cerebrospinal fluid. Note the mass effect and the displacement of the interhemispheric fissure to the right. There is no edema formation adjacent to the cyst.
Type IIB HC of the brain
HD with thyroid tissue involvement
Taeniasis saginata Taenia saginata is best diagnosed by stool examination for eggs and proglottids, but radiologic study may be of critical diagnostic importance when stool examination is negative. Characteristically the tapeworm appears as a single, gradually tapering ribbonlike filling defect in the barium column within the ileum. While typically attached to the jejunum, the proximal end is generally not demonstrable because it is so narrow. The linear filling defect is usually continuous, but discontinuities may be seen because only the wider portions of the worm in profile will be recognized.
Taeniasis saginata Radiologic distinction from the more common roundworm Ascaris lumbricoides may be easily accomplished.The roundworm is cylindrical, much shorter ( cm), and possesses an alimentary tract which may appear as a threadlike strand of barium within the filling Plain film showing tapeworm as ribbonlike density (arrows) within gas-containing ileal loop
Taeniasis saginata T. saginata is seldom demonstrated radiologically on small bowel barium studies. Characteristically it appears in the lower jejunum or ileum as an unusually long and gradually widening radiolucent line within the barium column. Unlike Ascaris, a tapeworm has no alimentary canal and thus does not ingest barium.
Adult T. saginata in the ileum.Reflux of barium into the terminal ileum during a barium enema revealed an elongated ribbon-like radiolucent shadow representing the adult tapeworm, which was coiled upon itself through part of its course. Small bowel series. continuous radiolucent structure running through multiple loops of jejunum and ileum
Cysticercosis (Outside the Central Nervous System) The calcified cysticercus produces single (rarely) or multiple (often several hundred) calcifications in the soft tissues, which are linear or oval in shape and usually measure 4-10 mm or more in length and 2-5 mm in width. The calcified cysts will have their long axes in the plane of the surrounding muscle bundle
Cysticercosis. showing typical rice grain calcifications in the soft tissues and muscles of the lower extremities.
Cysticercosis of the muscles of the back, abdomen, buttocks, and lower extremity. Note the alignment of the calcified cysticerci in the axes of the muscle fibers and their variation in shape from elongate and linear to more plump oval or elliptical configurations.
Cysticercosis involving the muscles of the neck, axillae, and chest wall
Neurocysticercosis routine radiographs of the skull: About 10% of patients known to have cysticercosis will show one or more cerebral calcifications. Over 75%, and in some series nearly 100%, will have calcifications in muscles or elsewhere in the soft tissues; In the brain, they occasionally show calcium deposition in their investing capsules; there may be an area of radiolucency inside and, in the very center, a tiny calcified scolex may sometimes be seen on careful inspection.
right lateral view of the skull reveal a solitary calcified cysticercus in the right frontal lobe
CT and MRI performed before or after administration of intravenous contrast media are the imaging methods of choice in neurocysticercosis, giving reliable information about the location and activity of the cysts. CT demonstrates : calcified and uncalcified cysts, free- floating cysts and hydrocephalus. MRI is of great value particularly in patients with lesions at the base of the brain, temporal lobes, and brain stem, as well as associated vascular insults. MRI is superior in delineating brain edema.
Neurocysticercosis In the CNS, the cysticercus, by way of the bloodstream, initially invades the subarachnoid space and then the cortical brain, especially at the junction of gray and white matter. Radiological classification : 1) vesicular stage: Is the viable stage of the parasite and appears as a low-density cyst on CT with minimal peripheral or no contrast enhancement. On MRI, it appears as a hypointense lesion on the T1- weighted image and hyperintense on T2-weighted. Commonly, on MRI a central or mural nodule is identified representing the scolex.
MRI. A : Axial T1- weighted, B : axial T2-weighted,C: coronal TI-weighted, postcontrast, and D: sagittal, postcontrast images. Note scolex within the cyst. Single cysticercus, vesicular stage
Neurocysticercosis 2) colloidal stage The cysticercal larva continues to undergo degeneration into the colloidal stage, where the cyst enlarges, the vesicular fluid turns dense, and the capsule becomes thickened and lobulated. There may be a host inflammatory reaction with formation of perilesional edema and peripheral contrast enhancement.
CT Scan of the brain shows: Multiple cysts in vesicular, (scolex inside the cyst are well identified) some cysts in colloidal stage surrounded by perilesional edema, and scanty calcified lesions on both cerebral hemisphere.
Post-contrast axial CT scan showing a thin, regular ring enhancing. cyst in the right parietal lobe (long arrow). Reduced attenuation of the adjacent, white matter represents edema(short arrow).
a)Post-contrast axial T1-weighted MRI showing a ring-enhancing cyst in the right parietal lobe. b)Corresponding axial T2-weighted MRI shows a hypo-intense capsule (long arrow ) with anterior thickening, representing a scolex. The center of the lesion is hyperintense. The adjacent brain edema is clearly depicted as a hyper-intense area (thick arrow) a) b)
ring enhancing lesions and vasogenic edema.
Neurocysticercosis 3) Calcified stage: The lesions are small and hyperdense on CT. This is the sequela of nonviable granulomas commonly seen in asymptomatic individuals. On MRI, small calcified lesions may be overlooked.
Scattered calcifications throughout the brain
Neurocysticercosis Arachnoidal type: when there is meningeal involvement, an intense inflammatory leptomeningeal reaction and fibrotic thickening producing arachnoiditis occur. The cysticercus cysts are isodense or isointense to CSF on CT and MRI respectively, and may be difficult to detect if they are small. The diagnosis may be inferred by focal deformity of the subarachnoid cisterns. Contrast enhancement of the meninges and obstructive communicating hydrocephalus may be seen on CT and MRI.
Neurocysticercosis Intraventricular type: The cysticercus cyst may be found anywhere in the ventricles, commonly in the midline leading to obstructive hydrocephalus, either acute or chronic. The intraventricular lesions may be isodense or isointense with CSF and there may be focal deformity of the affected ventricle.
Neurocysticercosis Racemose type: A conglomerate of vesicles appearing as multiloculated cystic masses in the subarachnoid,basal and sylvian cisterns attaining large size, lacking scolices, and producing significant compromise of the adjacent structures.
Sparganosis Except in the CNS, imaging shows no specific findings. Calcification has occurred in some of the spargana granulomas, and can be mistaken for cysticercosis. larger larvae could be recognized within a subcutaneous nodule by ultrasonography. An uncommon clinical presentation is eosinophilic urinary cystitis, with a localized mass (the granuloma around the worm) that can be recognized on ultrasonography, urography, or CT/MR scanning.
Sparganosis Worm granulomas have also occurred in the testes and epididymis, presenting a difficult differential diagnosis unless movement and change in position on rescanning are recognized. Wherever the "mass" is recognized, its mobility helps to establish the diagnosis (although sparganosis is not the only parasitic infection in which the area of interest moves around).
(A) Contrast-enhanced CT of the brain There is a 5-cm cystic lesion in the left occipital lobe showing ring enhancement. (B) MRI of the same patient shows considerable bright edema surrounding the cystic lesion.
Gadolinium-enhanced MRI showing the tortuous linear, beaded granuloma Sparganosis