Colonic Lymphoma

Axial (top) and coronal-reformatted (bottom) CT images show partial circumferential wall thickening (arrows) of the descending colon (C). Note smooth margin and homogeneous enhancement of bowel wall thickening, and disproportionate lack of colonic narrowing despite a large lesion. 

Facts:

• Lymphoma accounts for 0.2% - 1.2% of all colon malignancies
• Most common form of GI tract lymphoma is non-Hodgkin lymphoma (NHL)
• Most common sites of GI tract lymphoma is stomach, followed by small bowel
• For colonic lymphoma, most common site is cecum
• Nonspecific clinical signs and symptoms
• Due to rarity, Rx is not standardized. Often, it is surgically resected then chemotherapy is given

CT patterns of GI tract lymphoma:

• Nodular thickening of bowel wall
• Discrete polyp (causing intussusception)
• Long, distensible infiltrative lesion with ill-defined, thick walls with aneurysmal dilatation of the lumen
• Large exoenteric mass extending into adjacent soft tissues

Features differentiating lymphoma from adenocarcinoma of GI tract

• Bulky lymphadenopathy (lymphoma more likely)
• Marked luminal dilatation of bowel segment that is involved (lymphoma more likely)

Our case: Colonic mucosa-associated lymphoid tissue (MALT) lymphoma in a 67-year-old man.

References:

Buckley JA, Fishman EK. CT evaluation of small bowel neoplasms: spectrum of disease. Radiographics 1998;18:379.

Bairey O, et al. Non-Hodgkin lymphomas of the colon. Hematol 2006;8:832.

Uterine Leiomyoma on MRI

Leiomyoma in a 28-year-old woman. Sagittal MR images in T2W (A), T1W (B) and post-contrast T1W (C) show a large, rounded, circumscribed mass in the anterior wall of the uterus (U) that pushes the bladder (B) anteriorly. The mass demonstrates T2 hypointensity, T1 isointensity and heterogeneous enhancement. 

Facts

• Most common uterine neoplasms with prevalence up to 40% of women of reproductive age
• Benign tumors of smooth muscle with variable amount of fibrous tissue
• Surrounded by pseudocapsule and supplied by one or two large vessels
• Greater than 90% from uterine body
• Classified on their position relative to uterine wall (submucosal, intramural or subserosal)

MR Imaging Findings

• Well-circumscribed mass
• Classic signal intensity: T1 isointensity, T2 hypointensity, variable enhancement
• If T1 hyperintense, think hemorrhage
• If T2 hyperintense, think cellular leiomyoma
• If no enhancement, think partially or completely infarcted leiomyoma

References

Hricak H. MRI of the pelvis: a text atlas

Hamm B, et al. MRI and CT of the female pelvis. 

Sarcoidosis on PET/CT

(A) MIP image from a PET/CT shows areas of FDG avidity in multiple lymph node stations including hilar, mediastinal, axillary, upper abdominal and groin regions. Note intense uptake of the spleen. 

(B&C) Axial fused PET/CT images show intense FDG uptake within thoracic, axillary nodes and spleen. 

PET/CT: Three patterns of sarcoidosis

1. Typical: Bilateral hilar uptake extending to the mediastinum with bilateral lung uptakes (PET and CT concordant lesions). This is found in the majority of cases (about 2/3)
2. Discrepant: Multiple foci of uptake in and outside chest, along with splenic uptake (PET and CT discordant lesions). Fewer lesions are seen on CT than on PET. This pattern is the 2nd most common and is indistinguishable from malignancy (esp. metastasis, lymphoma)
3. Multiple small FDG avid lung lesions: This pattern is similar to lung metastasis. Fortunately, it is the least common pattern. 

Our case: Biopsy-confirmed sarcoidosis involving the hilar, mediastinal, upper abdominal lymph nodes, and spleen. This follows the "discrepant" pattern (basically meaning that malignancy cannot be reliably distinguished)

References:

Alavi A, et al. Positron emission tomography imaging in nonmalignant thoracic disorders. Semin Nucl Med 2002;32:293-321.

Pseudothickening of Colonic Wall

Axial and coronal-reformatted CT images of a 58-year-old woman show apparent circumferential wall thickening of the sigmoid colon (arrows) with a smooth transition into the more proximal colon. No pericolonic fat stranding is seen. Colonoscopy was performed but showed no colonic pathology.  Subsequent follow-up CT was also normal.  

Facts:

• When distended, normal colonic wall should be less than 3 mm or even imperceptible
• Fecal contents, fluid or colonic redundancy make true wall measurement difficult or impossible

Pseudothickening of Colonic Wall

• Could be mistaken for true pathology such as annular neoplasm or inflammatory stenosis
• Pseudothickening should be mild. Its margin should gradually return to full distention
• Normal pericolonic fat

References:

Mang T et al. Pitfalls in multi-detector row CT colonography: a systematic approach.. Radiographics 2007;27:431.

Macari M, Balthazar EJ. CT of bowel wall thickening significance and pitfalls of interpretation. AJR 2001;176:1105.

Hemochromatosis

A&C: MRI out-of-phase imaging. B&D: MRI in-phase imaging
Signal decrease of the liver on B&D (in-phase images) when compared with A&C (out-of-phase images). Note innumerable Gandy-Gamna bodies in the spleen. 

Facts

• Hemochromatosis = iron overload
• Primary vs. secondary hemochromatosis
• Primary: autosomal recessive genetic disorder involving increased iron absorption. This is the most common genetic disease in white population
• Secondary: nongenetic causes of iron accumulation in organs such as cirrhosis, myelodysplastic syndrome, thalassemia
• Diagnosis is made with serum ferritin level and transferrin saturation index (but low sensitivity and specificity), genetic test and biopsy. Biopsy is reference standard
• Imaging such as non-contrast CT and MRI can be used to diagnose hemochromatosis but MRI is the best method

MRI Findings

• Iron accumulation in tissues cause local distortion of magnetic fields and spin relaxation, resulting in shortening T1, T2 and esp. T2* 
• Loss of signal intensity in affected organs proportional to iron deposition
• Dual-sequence (gradient in and out of phase) is typically used 
• Decreased signal intensity on in-phase images compared with out-of-phase images "opposite of hepatic steatosis"
• General MR protocols are not adequate to estimate hepatic iron concentration. Special sequences (i.e., GRE T2* with progressively longer echo times) are needed for this purpose
• Iron excess deposition may suggest etiology
• Reticuloendothelial system (i.e., liver and spleen): secondary hemochromatosis
• Parenchymal depositition pattern (i.e., liver only, possible pancreas): primary hemochromatosis or chronic anemia with insufficient erythropoiesis
• Mixed deposition pattern (atypical distribution): anemia+multiple blood transfusions

This patient has hemochromatosis secondary to cirrhosis. 

Reference:

Queiroz-Andrade M et al. MR imaging findings of iron overload. RadioGraphics 2009;29:1575-1589. 

Slideshow: Imaging of Abdominal Trauma

Imaging of Abdominal Trauma from Rathachai Kaewlai

Blunt Traumatic Colon Perforation

Axial non contrast CT image of the abdomen shows a localized collection of air and high-density fluid (C) medial to the ascending colon (AC) and the site of colonic wall discontinuity (between arrows). Note skin and subcutaneous swelling/contusion of the right flank. 

Sagittal-reformatted CT image shows similar findings as  on the axial imaging. The entire length of the ascending colon (AC) is better appreciated and the collection (C) is located posteromedial to the colon within the retroperitoneal space. Colonic perforation was confirmed at surgery. 

Facts:

• Uncommon injury in blunt trauma
• Severe direct force is usually required to produce this injury, mostly from motor vehicle collision
• Often associated with other injuries, both intra- (liver, spleen, small bowel mesentery) and extra-abdominal (skeletal, facial, neurologic)
• CT may not be 100% sensitive. Findings could be overlooked in multiply-injured patients, large patients or if metallic monitoring/support devices are obscuring the area.
• "Normal" CT could be misleading when other factors such as physical examination is not taken into account. Re-review of images to look for subtle free fluid/air is essential in these cases.

CT Findings:

• Discontinuity of bowel wall
• Extraluminal contrast leakage
• Extraluminal air either intra- or retroperitoneal (nonspecific, can be seen after DPL, mechanical ventilation, barotrauma, etc)
• Intramural air
• Bowel wall thickening
• Bowel wall enhancement
• Mesenteric fat stranding
• Intraperitoneal and retroperitoneal fluid

References:

1. Barden BE et al. Perforation of the colon after blunt trauma. South Med J 2000;93(1)
2. Brody JM, et al. CT of blunt trauma bowel and mesenteric injury: typical findings and pitfalls in diagnosis. RadioGraphics 2000;20: 1525

Pancreatic Divisum

An MRCP image shows abnormal drainage of the main pancreatic duct and ventral duct into the minor papilla.

A diagram shows normal pattern of pancreatic duct drainage (label "normal") and pancreatic divisum. Several variants of pancreatic divisum exist but the "classic/typical" one is the MPD draining into the minor papilla while the VD draining into the major papilla along with the CBD. Santorinicele is a fusiform dilatation of the distal MPD before it enters the minor papilla. 

Facts: Pancreatic Divisum 

• Most common pancreatic anatomic variant, found 7% incidence at autopsy but frequencies differ at ERCP
• Controversial association with recurrent pancreatitis
• Results of non-fusion of ventral and dorsal pancreatic anlagen during embryonic time, therefore the ducts (ventral and dorsal ducts are not fused)
• Dorsal duct drains most of glandular parenchyma through minor papilla
• Ventral duct drains a portion of pancreatic head (including uncinate process) through major papilla

Imaging:

• Definitive diagnosis is made with ERCP. MRCP does have high sensitivity and specificity for diagnosis of divisum
• MDCT with thin section can be used to diagnose pancreatic divisum. Viewing images on PACS is essential for depiction of this condition and the assessment is possible only when the pancreatic duct is visualized.
• Important criterion = Dorsal duct seen from tail and body through the anterior aspect of the head, draining into minor papilla (located anterior to CBD and major papilla) while the ventral duct seen in posterior region of the pancreatic head and drains into duodenum together with CBD. Dorsal duct is larger than ventral duct and they are not communicated with each other. "Dominant dorsal duct sign"

Reference:

Soto JA, Lucey BC, Stuhlfaut JW. Pancreas divisum: depiction with multi-detector row CT. Radiology 2005; 235:503-508. 

Focal Hepatic Hot Spot Sign

An axial CT image shows a geographic area of hypervascularity (arrow) in segment IV of the liver. Note enlarged subcutaneous collateral vessels (arrowheads)

Facts: Focal Hepatic Hot Spot

• Focal area of enhancement in segment IV of liver due to presence of SVC obstruction
• Occurs due to portosystemic shunting between SVC and portal vein
• With SVC obstruction, blood may flow through internal mammary vein --> paraumbilical vein --> portal vein 
• Other causes of focal hot spots: Budd-Chiari syndrome (caudate lobe), liver abscess, hemangioma, FNH and HCC

Three Routes of Bypass of Venous Blood in Central Thoracic Venous Obstruction

1. Superior route: from subclavian vein to anterior jugular venous system (occuring in subclavian or brachiocephalic venous obstruction)
2. Posterior route: azygos-hemiazygos and paravertebral systems
3. Anterolateral route: like in our case, this is via anterior intercostal, internal mammary and long thoracic veins to IVC

Reference:

Maldjian PD, Obolevich AT, Cho KC. Focal enhancement of the liver on CT: a sign of SVC obstruction. J Comput Assist Tomogr 1995;19:316-8

Renal Ultrasound for Elevated Serum Creatinine

A sagittal ultrasound image of the right kidney shows a normal-sized kidney with normal parenchymal echogenicity in a patient with acute renal failure. 

What clinicians want to know is whether elevated serum creatinine "acute or chronic" 

• This information is important to narrow differential diagnosis, urgency of investigation and treatment. 
• Chronicity of renal dysfunction can be determined with 1) a search for previous measures of renal function (i.e., old labs), 2) clinical history (i.e., recent onset of acute illness, oliguria that would suggest acute renal failure), 3) daily deterioration of renal function (suggestive of acute renal failure - ARF), 4) ultrasound
• ARF can be prerenal, renal or postrenal

Why Ultrasound?

• Ultrasound can help determining the kidney size. Small renal size (less than 8 cm in adults) is suggestive of CRF
• Demonstrate hydronephrosis, suggesting a postrenal cause. Note that to produce ARF, both kidneys must be affected (i.e., bilateral ureteric obstruction or bladder outlet obstruction, or hydronephrosis of a single functioning kidney)
• To exclude obstruction, US should be done as early as possible. But US is not necessary if there are "clear reversible causes on initial assessment + Rx instituted + clear evidence of prompt response with return to normal renal function within a few days"
• Increased echogenicity of renal cortex is not a sensitive measure of renal function. When present, it is more commonly seen in tubulointerstitial disease rather than glomerular disease

Limitations of Ultrasound

• No hydronephrosis is not equal to no obstruction. False negative study can occur 1) in the first few days of obstruction because the collecting system is relatively noncompliant, 2) if ureters and collecting systems are encased by tumor or fibrosis
• Detection of hydronephrosis can be difficult in patients with cystic kidney disease

Reference:

Baxter GM, Sidhu PS. Ultrasound of the urogenital system, 2006.

Gallbladder Cholesterolosis

Longitudinal US image of the gallbladder demonstrates multiple tiny echogenic spots within the wall with comet-tail artifacts. No evidence of gallbladder wall thickening. 

Facts:

• Other names: cholesteatosis, strawberry gallbladder
• Common, degenerative, proliferative changes of gallbladder
• Usually in females during their 4th and 5th decades
• Usually asymptomatic
• Not associated with increased risk of malignancy, cholelithiasis or cholecystitis

Differentiation from Adenomyomatosis:

• May be difficult at times because they may coexist and are believed to be a continuum of same pathology
• In cholesterolosis, the gallbladder has normal size, shape, lumen and often normal wall thickness

Reference:

Schmidt G. Differential diagnosis in  ultrasound imaging: A teaching file, 2006

Atypical Hepatic Hemangioma - Echoic Border

Ultrasound images of the liver show a round hypoechoic nodule (arrow, calipers) in the right lobe with an echoic border. Background fatty liver is noted. 

Hemangioma with Echoic Border

• Frequent atypical pattern at ultrasound
• Can have either thick echoic rind or thin echoic rim
• Internal echo is at least partially hypoechoic, which is assumed to represent previous hemorrhage, necrosis, scarring or myxomatous change

Reference:

Vilgrain V, et al. Imaging of atypical hemangiomas of the liver with pathologic correlation. Radiographics 2000; 20:379.

Atypical Hepatic Hemangioma - Rapid Filling of Contrast

Axial MR images in multiple phases (as labeled) show a T1 hypointense nodule in the right hepatic lobe that rapidly filled in with contrast after administration and subsequently fades on delayed imaging. Note that the enhancement of the nodule is similar to the aorta in all phases. On T2W image (not shown), this nodule has a very high signal intensity. 

Rapidly Filling Hemangioma

• 16% of all hepatic hemangiomas
• More common among small (<1 1="1" 42="42" cm="cm" hemangioma="hemangioma" hemangiomas="hemangiomas" in="in" incidence="incidence" less="less" li="li" of="of" than="than">
• Immediate homogeneous enhancement at arterial phase and hyperintensity persists in delayed phases. Enhancement equal to aorta in all phases. 
• High T2 signal intensity may be helpful for differentiation from other arterial enhancing nodules (but it can also be seen in islet cell tumor metastasis)

Reference:

Vilgrain V et al. Imaging of atypical hemangiomas of the liver with pathologic correlation. Radiographics 2000; 20:379

Focal Fat Sparing

Figure 1: US image of the liver shows focal masslike area of hypoechogenicity of the left lobe posterior to the left portal vein branch. Note high echogenicity of the background liver, suggesting fatty change.

Figure 2 & 3: In-phase and out-of-phase MR images show liver signal intensity drop in the chemical shift imaging confirming diffuse fatty liver. The abnormality in the left lobe liver does not change between the two phases, suggesting a focal area of fat sparing.

Facts: Fatty Liver

• Most common abnormality of the liver seen on cross-sectional imaging
• Common patterns: diffuse fat accumulation, diffuse fat accumulation with focal sparing, and focal fat accumulation in an otherwise normal liver
• Unusual patterns may mimick neoplasm, inflammation or vascular conditions
• Pathology: triglyceride acculation within cytoplasm of hepatocytes
• Term "fatty liver" is preferred over "fatty infiltration of the liver" because triglyceride accumulation occurs within hepatocytes but rarely other cell types. Infiltration of fat into parenchymal does not occur

Imaging Findings and Sensitivity/Specificity

• US: 1) Liver echo greater than renal cortex and spleen with attenuation of sound wave, 2) loss of definition of diaphragm, 3) poor delineation of intrahepatic architecture (to avoid false-positive diagnosis, all three findings should be fulfilled).  Sensitivity 60-100%. Specificity 77-95%.
• CT: Liver attenuation 10 HU less than that of spleen, or less than 40 HU. Sensitivity 43-95%. Specificity 90%.
• MRI: Signal intensity loss on opposed-phase images in comparison with in-phase images. Sensitivity 81%. Specificity 100%.

Patterns

1. Diffuse deposition: most common
2. Focal deposition and focal sparing: characteristically in specific areas (adjacent to falciform ligament or ligamentum venosum, porta hepatis, in GB fossa). Suggestive findings of fatty pseudolesions rather than true masses are:
1. Fat content
2. Characteristic location
3. Absence of mass effect on vessels and other liver structures
4. Geographic configuration (not round or oval)
5. Poorly delineated margin
6. Contrast enhancement similar to or less than that or normal liver parenchyma
3. Multifocal deposition
4. Perivascular deposition
5. Subcapsular deposition

Reference:


Hamer OW, Aguirre DA, Casola G, et al. Fatty liver: imaging patterns and pitfalls. Radiographics 2006;26: 1637-1653.

ESWL-induced Perinephric Hematoma

Ultrasound image of the kidney shows a crescentic heterogeneous hypoechoic lesion in the perinephric space (arrows). The kidney is marked by the calipers. 

Axial unenhanced CT images confirm a thick left perinephric hematoma (stars) and several fragmented stones in the lower pole of the left kidney.

Facts

• ESWL (Extracorporeal Shock Wave Lithotrypsy) is a common and standard treatment for renal/proximal ureteric calculi in majority of patients
• Most common complication = microscopic hematuria
• Perinephric hematoma and infection (including pyelonephritis) can occur
• Incidence of hematoma varies depending on method of diagnosis. By US, incidence is about 0.1-0.6%. By CT/MRI, incidence rises to 20-25% of cases. 
• No clear correlation between number of shockwaves or intensity given and incidence of hematoma
• Most perinephric hematoma resolves spontaneously within 2 years and the renal function is preserved. They are mostly treated conservatively

Imaging: US and CT

• Crescent-shaped collection surrounding the affected kidney
• Hypoechoic on US, hyperattenuating on non-contrast CT and no enhancement after IV contrast
• Displacement or compression of adjacent renal parenchyma
• Differentiate from subcapsular hematoma by appearance and pressure effect to underlying kidney.
• "Page" kidney occurs when (usually) subcapsular hematoma causes chronic renal parenchymal compromise and then hypertension

Reference:
Labanaris AP, Kuhn R, Schott GE, Zugor V. Perirenal hematomas induced by extracorporeal shock wave lithotripsy (ESWL). Therapeutic management. TheScientificWorldJOURNAL 2007;7:1563-1566.

Pyonephrosis

 Longitudinal ultrasound image of the right kidney shows moderate right hydroureteronephrosis (arrows) with internal debris.

Longitudinal image of the right ureter (arrows) shows a stone (arrowhead) in the distal ureter causing proximal hydroureter. 

Facts:

• Bacterial infection of urine associated with ureteral obstruction, AKA infected hydronephrosis. Accumulation of pus in the renal pelvis and calices of the kidney
• Common causes are ureteric obstruction by stone and ureteropelvic junction (UPJ) obstruction
• Septic patients with high fever, flank pain and tenderness
• Any febrile patients with hydronephrosis should be suspected of having pyonephrosis
• Ultrasound: echogenic urine and debris in the hydronephrotic kidney
• Prompt drainage essential 

Reference:

Hodler J, Von Schulthess GK, Zollikofer ChL. Diseases of the abdomen and pelvis 2010-2013

USPSTF Recommends Against PSA-based Prostate Cancer Screening

In its newest Statement published yesterday in the Annals of Internal Medicine, the U.S. Preventive Services Task Force (USPSTF) recommends against PSA-based screening for prostate cancer. Read the full paper (free) here.

Prostate Cancer: Facts

• Most commonly diagnosed non-skin cancer in men in USA, estimated lifetime risk 15.9%
• Most cases have good prognosis even without treatment
• Lifetime risk of dying of prostate cancer 2.8%

Screening with PSA

• PSA-based screening programs detect many cases of asymptomatic prostate cancer but evidence suggests that many of them will not progress or will progress slowly that it would have remained asymptomatic for the lifetime
• "Overdiagnosis" of prostate cancer based on PSA is between 17-50% 
• Screening resulted in none or minimal reduction in prostate cancer mortality (0 to 1 prostate cancer deaths avoided per 1000 men screened)
• "False positivity" near 80% (cutoffs value 2.5-4 ug/L)

Recommendation

• Applies to men in general US population. Although older age is the strongest risk factor for development of prostate cancer, neither screening nor treatment trials show benefit in men older than 70 years
• Decision to initiate or continue PSA screening should be understood by patients about possible benefits and harms of screening

Recommendations of Others

• The American Urological Association, the American Academy of Family Physicians and the American College of Physicians: currently updating their guideline
• The American Cancer Society: men at average risk beginning at age 50 years and black men or men with a family history of prostate cancer beginning at age 45 years

Reference:

Annals of Internal Medicine May 21, 2012  LINK

Cesarean Section Scar Diverticulum

A sagittal US scan of the uterus shows a cystic lesion in the anterior wall of the lower uterine segment. The patient reported prior cesarean section

Facts:

• Defect within the lower uterine cavity in patients with history of cesarean section in expected location of a hysterectomy incision
• Based on a study utilizing hysterosalpingograms, 60% of women with prior C-section had this anatomic defect
• Knowledge of this anatomic defect avoids misdiagnosing it as other pathology
• Often benign clinical significance. Some reports of ectopic scar pregnancy and abnormal uterine bleeding associated with this pathology

Imaging Appearance

• Focal outpouching (most common feature) and thin linear defect
• Location: lower uterine segment (most common) > uterine isthmus, upper endocervical canal

Imaging Mimics

• Prominent cervical glands (tubular, symmetric structure from both walls of endocervical canal)
• Postmyomectomy diverticula (unilateral, from site of resection, correlated with surgical history and location of diverticula)
• Gartner's duct cyst (long, tubular structure parallel to uterine cavity)
• Adenomyosis (location of defect anywhere along uterine cavity)

Reference

Surapaneni K, Silberzweig JE. Cesarean section scar diverticulum: appearance on hysterosalpingography. AJR 2008;190:870-4

Is Plain Radiography Sensitive Enough to Detect Pneumoperitoneum?

An upright chest radiograph shows a large amount of pneumoperitoneum under the right hemidiaphragm of a patient who has peptic ulcer perforation found at surgery.

Facts: Pneumoperitoneum & GI perforation

• Common
• Requires a breach through all layers of hollow viscus that would allow escape of intraluminal content into the peritoneal cavity
• Results in peritonitis, either localized or generalized

Detectability Rate of Imaging

• Plain radiography sensitivity ranges from 50% to 98% depending on the technique (upright chest, upright abdomen, left lateral decubitus, supine abdomen) and additional postural maneuver
• Recent study of 1,723 patients with GI perforation shows that radiography (either upright chest, upright abdomen or both) has positivity rate of almost 90%. 10% of radiographs did not show free air despite patients having GI perforation. Highest positivity rate was seen with gastric and duodenal perforation (94%), but lowest with appendiceal perforation (7%)

Reference:

Bansal J, Jenaw RK, Rao J, et al. Effectiveness of plain radiography in diagnosing hollow viscus perforation: study of 1,723 patients of perforation peritonitis. Emerg Radiol 2011 December.

Intestinal Ascariasis

Author: Santip Srisuwan, M.D.

Axial CT image shows multiple tubular filling defects (arrows) within the opacified lumen of the small bowel. Note contrast filling within the filling defects.

Facts:

• Most common helminthic infection (worldwide prevalence 25%)
• Usually asymptomatic.
• Possible symptoms are colicky abdominal pain in adults and growth retardation/intussusception/volvulus in children

Imaging

• X-ray: usually normal but may present as bowel obstruction (partial or complete), or soft tissue masses
• US: hypo echoic curvilinear tubular structures with well-defined echogenic walls and curling movement of the worm during the exam
• CT: long, thin tubular structure coiled within the small bowel, outlined by oral contrast materials

References:

1. Hommeyer SC, Hamill GS, Johnson JA. CT diagnosis of intestinal ascariosis. Abdom Imaging 1995;20:315-316.

2. Rodrigues EJ, Gama MA, Ornstein SM, et al. Ascariasis causing small bowel volvulus. Radiographics 2003;23:1291-3.

3. Villamizar E, Mendez M, Bonilla E, et al. Ascaris lumbricoides infestation as a cause of intestinal obstruction in children: experience with 87 cases. J Pediatr Surg 1996;3:201-4.

4. Hendi JM, Horton KM, Fishman EK. Ascariasis infection of the colon: MDCT evaluation. Emerg Radiol 2006;12:180-1.

5. Bude RO, Bowerman RA. Case 20: Biliary ascariasis. Radiology 2000;214:844-7.

6. Hershkovitz D, Wasserberg N. Large bowel obstruction due to Ascaris lumbricoides. IMAJ 2004;6:115-116.