Wednesday, July 29, 2009

Non Alcoholic Steatohepatitis (NASH)


15 year old male obese boy came with pain in abdomen with elevated liver enzymes. He is non alcoholic, not taking any medication and tests negetive for hepatitis. MRI abdomen T1 weighted image shows diffuse fatty infilteration in the liver which is confirmed by loss of signal on ooposed phase chemical shifgt image. Findings are consistent with Non Alcoholic Steatohepatitis (NASH).

Synonyms: Hepatic fatty metamorphosis , Hepatic fatty steatosis, NASH
Nonalcoholic steatohepatitis (NASH) is fat in the liver, with inflammation and damage. It resembles alcoholic liver disease, but occurs in people who drink little or no alcohol. The major feature in NASH is fat in the liver, along with inflammation and damage.Patients generally feel well in the early stages and only begin to have symptoms—such as fatigue, weight loss, and weakness—once the disease is more advanced or cirrhosis develops.

We have to differentiate "Fatty liver", NASH and nonalcoholic fatty liver disease (NAFLD). Fat in their liver, but no inflammation or liver damage, a condition called “fatty liver. If fat is suspected based on blood test results or scans of the liver, this problem is called nonalcoholic fatty liver disease (NAFLD). If a liver biopsy is performed in this case, it will show that some people have NASH while others have simple fatty liver. Main causes for the NASH are elevated blood lipids, such as cholesterol and triglycerides, and many have diabetes or pre-diabetes, obesity.

USG shows diffuse increase in echotexture. CT scan will show diffuse decrease in attenuation. MRI shows intracellular fatty infilteration which is diffusely hyperintense on T1 weighted image (in phase image) and shows loss of signal on opposed phase chemical shift image. These MRI findings in patient with elevated liver enzymes suggestive of NASH. Liver biopsy and histopathology are diagnostic.

Tuesday, July 28, 2009

Tarlov Cyst


25 year old young male came with radicular pain to lower limb on right side referred for MRI LS spine. MRI T2 weighted para saggital image shows well defined rounded hyperintense lesion in the D12-L1 intervertebral foramen causing compression on the exiting nerve root on right side. CISS 3D axial image shows the lesion better (arrow).

Tarlov or perineurial cysts are pathological formations located in the space between the peri-and endoneurium of the spinal posterior nerve root sheath. Tarlov cysts are rare causes of low back pain. They are more common in females. Clinical presentation of Tarlov cysts is variable. The cysts may cause local and/or radicular pain. Depending on their location, size and relationship to the nerve roots, they may cause sensory disturbances or motor deficits to the point of bladder dysfunction.

Radiograph is usually normal, it may show bony erosion or widening of foramen on oblique views. Conventional myelography may show extradural indentation on the thecal sac however MRI is needed for confirmation of the lesion. CT scan can demonstrate cystic lesion isodense with CSF located at the foramina. Bony changes may also be present. MRI shows welldefined CSF intensity lesion in the prineural location predominantly in lumbar and sacral region. The lesions may be seen in the cauda equina and other nerve roots.

Saturday, July 25, 2009

Supraspinatus Tendonitis

44 year old male patient came with painfull arc of shoulder movement, T1 weighted oblique coronal image shows hyperintense abnormal signal seen in the supraspinatous tendon (arrow).

Supraspinatus tendonitis is often associated with shoulder impingement syndrome. The common belief is that impingement of the supraspinatus tendon leads to supraspinatus tendonitis (inflammation of the supraspinatus/rotator cuff tendon and/or the contiguous peritendinous soft tissues), which is a known stage of shoulder impingement syndrome.

It is basically chronic degenerative tendinitis leading to some degree of mucoid degeneration seen on MRI as increased signal intensity without altered rotatory cuff contour. Increased signal intensity appreciated on T1 and PD weighted images.

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Arnold chiari malformation type 1

T2 W MR sagittal cervical spine image shows herniation of cerebellar tonsils with extensive syrinx in cervical and dorsal spinal cord.

Chiari I malformation (CMI) is characterized by herniation of the cerebellar tonsils through the foramen magnum into the cervical spinal canal. The cerebellar tonsils often are elongated and peglike. Mild caudal displacement and flattening or kinking of the medulla may be present. The vermis cerebelli and the fourth ventricle are normal or only minimally deformed. Its symptoms may result in occipital headache, difficulty swallowing, numbness and tingling in the hands.
Distention with cerebrospinal fluid (CSF) of the central canal of spinal cord (ie, hydromyelia) or paracentral cavities (Syringomyelia) is present in approximately 25% of patients with CMI. The cervical cord is the most common site of syringohydromyelia.

Classification:
TypePresentationOther notes
IIs generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.The most common form.
IIUsually accompanied by a myelomeningocele leading to partial or complete paralysis below the spinal defect. Abnormal development of the cerebellar vermisand medulla oblongata occur, and they both descend into the foramen magnum. Hydrocephalus is frequently present.
IIICauses severe neurological defects. It is associated with an encephalocele.
IVCharacterized by a lack of cerebellar development.
Here is a youtube link to a nice video created by on of the patients father..........

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Renal vein thrombosis (RVT)

45 Year old male doctor presents with breathlessness and fever, pulmonary angio revealed thromboembolism in segmental pulmonary arteries on right side. Bilateral lower limb doppler is negetive. Patient was obese to carryout abdominal doppler. MR angiogram thick MIP image shows partially occluding thrombus in the left renal vein extending partially in to IVC (arrow).

Although renal vein thrombosis (RVT) has numerous etiologies, it occurs most commonly in patients with nephrotic syndrome. The renal vein also may contain thrombus after invasion by renal cell cancer (Resources from Elsevier’s OncologySTAT). Other less common causes include renal transplantation, Beh├žet syndrome, hypercoagulable states, and antiphospholipid antibody syndrome.

Although colour doppler can pick up renal vein thrombosis, CT and MRI are better midalities for the diagnosis.

Fracture of the Dens (Type 1)

24 Year old male came with motor vehicle accident with pain in neck, Sagittal T1 W and Coronal STIR MRI images of cervical spine shows an oblique fracture in the tip of odontoid process (arrow). No cord compression.

Discussion:

  • Most dens fractures are caused by motor vehicle accidents and falls
  • About 1/3 of C-spine injuries occur at C2 and about ½ at C6-C7
  • As expected, most fatal cervical spine injuries occur at C1 or C2
  • Most odontoid fractures occur with flexion, extension and rotation.
  • Classification of dens fractures:
    • About 15% of all cervical spine fractures
    • Classified by location (Anderson and D’Alonzo classification)
      • Type I (<5%)
        • Tip of dens at insertion of alar ligament which connects dens to occiput
        • Usually stable but may be associated with atlanto-occipital dislocation
      • Type II (>60%)
        • Most common dens fractures
        • Fracture at base of dens at its attachment to body of C2
      • Type III (30%)
        • Subdentate—through body of C2
        • Does not actually involve dens
        • Unstable fracture as the atlas and occiput can now move together as a unit
    • Other fractures include a rare longitudinal fracture through dens and body of C2
  • Imaging findings
    • Conventional radiography is frequently first used as it tends to be most available
    • CT is better at demonstrating fractures
    • MRI is used for evaluation of ligamentous, disk, spinal cord and soft tissue injuries
    • Posterior displacement of the fractured dens into the spinal canal is more common than other displacements
    • Lateral view on conventional radiography is most useful as most (85-90%) of injuries can be seen on lateral view
    • Cervicothoracic junction visibility assures that the entire cervical spine is visualized
    • Soft tissue findings may include >5 mm of prevertebral soft tissue at C3 or less than half of the AP diameter of the adjacent vertebra
      • At level of C6, prevertebral soft tissue should be no more than 22 mm in adults and 14 mm in children younger than 15 years
    • Widening of the predentate space to greater than 3 mm is abnormal
  • Pitfalls
    • A mach line may appear to traverse the base of the dens on the open-mouth (aka as the atlantoaxial or odontoid) view but should be recognized by the superimposed base of the occiput
      • The mach line will not be present on the lateral view of the dens
    • A smooth and sclerotic edge to the “fracture” usually indicates either congenital non-union or acquired non-union of the dens to the body of C2
  • Treatment
    • Type I fractures are usually treated with a hard collar for 6-8 weeks
    • Type II fractures can be treated with
      • Immobilization for 12-16 weeks
      • Operative fixation (odontoid screw)
      • Arthrodesis of C1 to C2
    • Type II fractures can be treated with a halo or surgically, as Type II fractures
  • Complications
    • Non-union
      • Due to limited vascular supply
      • May occur in 30-50% of Type II fractures, especially in elderly
    • Malunion
    • Pseudarthrosis
    • Affected by age of patient, amount of displacement.
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Wednesday, July 15, 2009

Horse shoe kidney


The term horseshoe kidney refers to the appearance of the fused kidney, which results from fusion at one pole. In more than 90% of cases, fusion occurs along the lower pole. Technically, the term horseshoe kidney is reserved for cases in which most of each kidney lies on one side of the spine. It includes symmetric horseshoe kidney (midline fusion) or asymmetric horseshoe kidney (L-shaped kidney). In the latter, the fused part, or isthmus, lies slightly lateral to the midline (lateral fusion). Horseshoe kidney is generally differentiated from crossed fused ectopia, in which both fused kidneys lie on one side of the spine, and the ureter of the crossed kidney crosses the midline to enter the bladder.
Horseshoe kidney is the most common renal fusion anomaly, the incidence being about 1 case per 400 persons worldwide. As reported, it can occur in a single member of a set of identical twins and in both members. At present, no clear evidence of a hereditary trait exists.

Complications of horseshoe kidney include the following:

  • Ureteropelvic junction (UPJ) obstruction is a common complication, possibly because of the high insertion of the ureter.
  • Recurrent infections occur because of urine stasis and associated vesicoureteric reflux.
  • Recurrent stone formation related to UPJ obstruction or infection may occur.
  • An increased risk of trauma to the isthmus exists because of its position anterior to the spine.
  • Horseshoe kidney may pose problems for surgeons during abdominal surgery for other abdominal problems.
  • Evidence indicates that an increased incidence of certain renal tumors is associated with horseshoe kidney.


Tuesday, July 14, 2009

Rheumatoid pneumoconiosis (Caplan's Syndrome)



High resolution CT of 84 year old man with rheumatoid arthritis. a) Mediastinal window image showing cavitatory lesions in bilateral upper lobes (arrows) with large fibrotic area in right upper lobe (arrow head) and few subpleural fibrotic lesions (arrows in image [b]) in left upper lobe. c) High resolution CT scan lung window shows multiple diffuse reticulonodular lesions in bilateral lungs these features suggestive of pneumoconiosis with progressive massive fibrosis (PMF).

It is also known as Caplan's Syndrome, associated with coal worker's pneumoconiosis and silicosis. The incidence is falling as the coal mining industry has been in decline. Chest radiograph shows multiple, well defined, rounded opacities, 0.5 to 5 cm in diameter distributed throughout the lungs with or without eggshell calcification of hilar lymph nodes. HRCT findings include small nodules with perilymphatic distribution associated with necrobiotic nodules demonstrating cavitation, which are indistinguishable from tubercular cavity. The active inflammatory zone around the rheumatoid pneumoconiotic nodules distinguishes from nonrheumatoid pneumoconiotic nodules. Progressive massive fibrosis (PMF) is irregularly outlined few soft tissue nodules with surrounding fibrosis in apical regions, more often seen with simple pneumoconiosis than Caplan’s syndrome.

Wednesday, July 8, 2009

Tracheal bronchus


5 month old male child with acute respiratory tract infection, CT coronal reformatted lung window shows bronchus arising from the trachea on right side (arrow) and the virtual bronchoscopy image shows the tracheal bronchus opening better.

The term tracheal bronchus refers to an abnormal bronchus that comes directly off the lateral wall of the trachea (ie, above the main carina) and supplies ventilation to the upper lobe. It is most often an asymptomatic anatomical variant found on bronchoscopy. There is an association
between tracheal bronchus and other congenital malformations, mainly malformations of the ribs and vertebrae. Patients with Down syndrome have a higher incidence of tracheal bronchus. The anomalous bronchus can arise anywhere from the carina to the cricoid cartilage, but most frequently within 2 cm of the carina. Tracheal bronchi are classified as being either “displaced” or “supernumerary.”
If the entire right upper lobe takes off from the trachea the right main bronchus is the bronchus intermedius, feeding the right middle and lower lobes, and the malformation is called “true tracheal bronchus” or “bronchus sui” (“pig bronchus,” because that is the normal morphology in pigs). The incidence of true tracheal bronchus is 0.2%.
If the anomalous bronchus is the take-off of the apical segment of the right upper lobe, as was the case in our patient, the right main bronchus will be normal looking, but the right upper lobe will not have its trifurcation. Instead there will be a bifurcation, corresponding to the anterior and posterior segments. That variant is called “apical tracheal bronchus,” which has been described in patients who have an azygos lobe. In that situation the apical segment will have its own displaced bronchus and its ownpleural investment. Vascular supply and venous drainage are usually normal in the displaced bronchus variant and are provided by the pulmonary artery and pulmonary veins.
The majority of patients with tracheal bronchi are asymptomatic and do not require any medical intervention. In the case of recurrent pneumonia complicated by bronchiectasis surgical resection of the anomalous lobe or segment is the treatment of choice.

Sunday, July 5, 2009

Spine fracture in Ankylosing Spondylitis

38 year old male patient with ankylosing spondylitis met with mild trauma following which he presented with para paresis, Sagittal T2 weighted MR image showing anterior displacement of C6 over C7 (Arrow head) and multiple syndesmophytes in all the cervical levels (short arrow). There is cord hyperintensity at the levels of C6, C7 and D1 suggestive of cord contusion due to fracture.

The diffuse paraspinal ossification and inflammatory osteitis of advanced ankylosing spondylitis creates a fused, brittle spine that is susceptible to fracture. Even minor trauma can produce an unstable injury as a result of disruption of the ossified supporting ligaments.

Thoracolumbar fractures are reported less frequently than cervical injuries in patients with ankylosing spondylitis.Three recognized patterns are simple vertebral compression fractures, transversely oriented shear fractures, and stress fractures associated with pseudoarthrosis. Transversely oriented shear fractures are acute fractures of the ankylosed spine that invariably disrupt the ossified supporting ligaments and usually traverse the disk space. Disruption of all three columns of the spine predisposes the fracture to displacement and neurologic injury. Stress fractures associated with pseudoarthrosis are subacute injuries that constitute part of the spectrum of spondylodiscitis, a destructive discovertebral (“Andersson”) lesion, that tends to occur in the thoracolumbar region. End-plate erosions and disk height changes, with vertebral sclerosis or osteolysis, can be seen radiographically.

Shiny corner sign in Ankylosing Spondylitis


38 year old male with recently diagnosed ankylosing spondylitis, lateral lumbar spine radiograph showing increased density (arrow) in the anteroinferior part of L3 vertebral body suggetive of shiny corner sign. MR STIR image shows increased signal in anteroinferior parts (arrows) of L3 and L5 bodies.

Shiny corner sign, also known as a Romanus lesion, is an early spinal finding in ankylosing spondylitis. These represent small erosions at the superior and inferior endplates (corners on lateral radiograph) of the vertebral bodies, with surrounding reactive sclerosis. Eventually the vertebral bodies become squared.

On MRI the 'shiny corners' appear as areas of increased T1 signal due to focal fatty marrow as a result of chronic inflammation. MRI however can detect changes earlier than x-ray manifestations, when there is initially increased T2 signal on STIR and decreased signal on T1WI. At this stage plain films appear normal.

Small-cell lung carcinoma invading the left atrium



60 year old male came with progressive shortness of breath and chest pan, Contrast enhanced CT scan showed large heterogenously enhancing lesion (arrow in first image) in the left perihilar and lower lobe region occluding the left lower lobe bronchus completely. The lesion is partially encasing the descending thoracic aorta and extending in to the left atrium through the inferior pulmonary veins (arrow in secong image and arrow head in third image) . The biopsy of the lesion revealed Small cell carcinoma of lung.

Direct intravascular, cardiac extension and spread of bronchogenic carcinoma is an uncommon event. when tumor extends to left atrium, special techniques are needed is resectrion of still to be attempted.
The cardinal imaging signs of intarvenous extension of bronchogenic carcinoma on CT or MRI is filling defect of soft tissue density within the lumen of pulmonary vein and left atrium, which is continous with the primary mass. Obliteration of superior pulmonary vein is regardes as suggesting as intrapericardial tumor extension. CT remains the standard staging investigation for lung carcinoma.

Saturday, July 4, 2009

Congenital Cystic Adenomatoid Malformation (CCAM)



2 Month old male baby came with shortness of breath. CT scanogram shows large cystic lesion in the right upper zone. Axial and coronal CT lung window shows large cyst in the right upper lobe with septa within s/o Typer I congenital cystic adenomatoid malformation.

CCAM is a congenital anomaly of the terminal brochioles which results in a dysplastic, multicystic mass. These cysts usually communicate with the bronchial tree. At birth, these cysts are fluid-filled. Ultimately, communication with the airway allows for the fluid-filled mass to become air-filled. Whether fluid-filled or air-filled, the cysts become increasing larger, exert mass effect, compress mediastinal structures and lung parenchyma.

Infants less than one year old usually present with respiratory distress. Usually, the abnormality is confined to one lobe. There are three types of CCAM:

  1. Type I: Single/multiple cysts > 2cm (most common).
  2. Type II: Smaller cysts <2cm
  3. Type III: Solitary solid mass. (Multiple microcysts of 2-6 mm).
The differential diagnosis includes congenital lobar emphysema and bronchial atresia.

Treatment: Surgical lobectomy is curative with Type I. There is increased morbidity and mortality with Type II and II because the lesions are often larger at presentation.

References:

  1. Brickman H. Pediatric Radiology: The Requisites, 2nd Edition, 1998.
  2. Swischuk L. Imaging of the Newborn, Infant and Young Child, 3rd Edition, 1989.

Posterior Urethral Valve (PUV)


10 Month old child came with repeated UTIs. MCUG (Micturiting cystourethrography) shows irregular outlines bladder mucosa with multiple small diverticula. There is vesicoureteral reflux on the left side. The posterior urethra is dilted with hypertrophy of bladder neck and lucency between the bladder neck and posterior urethra giving the typical appearance of spinning top. Features suggestive of posterior urethral valve.

A posterior urethral valve is an abnormal congenital obstructing membrane that is located within the posterior male urethra; this valve is the most common cause of bladder outlet obstruction in male children. A posterior urethral valve occurs in approximately 1 in 5000 live male births.

There are 3 types of posterior urethral valves.The type I valve is a bicuspid valve that radiates distally from the posterior edge of the verumontanum to the anterior proximal membranous urethra. It account for 95% of all valves. The type II valve is no longer considered an obstructing valve; rather, it is thought to be a sequela of voiding dysfunction. It was described as a hypertrophic band of superficial muscle that runs along the posterolateral wall of the urethra from the ureteral orifice to the verumontanum. Therefore, these valves can be differentiated from type I and type III valves by their location proximal to the verumontanum. The type III valve is a circumferential membrane or diaphragm that is located at the membranous urethra, which is thought to result from the incomplete regression of the urogenital membrane during embryogenesis. There is a central aperture, and the central portions of the ring may prolapse into the more distal urethra during voiding, which results in a wind-sock appearance on VCUG. Type III valves account for almost 5% of all valves.

VCUG (Voiding cystourethrography) is considered the diagnostic study of choice for the evaluation of posterior urethral valves. The bladder is typically thickened with trabeculae and may exhibit vesicoureteral reflux or, less commonly, diverticula. The bladder neck is typically hypertrophic, leading to a lucent ring or collar. On voiding, the posterior urethra is dilated (ie, shield shaped), and valve leaflets may be seen as lucencies, giving the appearance of a spinning top. If leaflets are not visible, a commonly associated finding of posterior urethral bulging distally over the bulbar urethra may be noted. The anterior urethra is typically underfilled, and voiding is incomplete.

IVP is not routinely used in children because the contrast agent is poorly concentrated and visualized in newborn kidneys, particularly if renal function is diminished. Elevated serum creatinine levels may preclude the use of intravenous (IV) contrast material. IVP can show an absent kidney in the case of renal dysplasia or delayed renal function with persistent high intraluminal pressures. Hydroureteronephrosis may be seen. Delayed images may show bladder or urethral pathology, but the lower urinary tract is better visualized with VCUG.

CT scans with IV contrast enhancement may reveal dysplastic and/or dilated kidneys with delayed renal function and excretion, hydroureter, dilated bladder with wall thickening, trabeculation, and diverticula. A dilated posterior urethra might be seen, although leaflets may be easily missed. Elevated serum creatinine levels generally preclude use of IV contrast material. MRI findings are similar to those of CT scanning except that enhancement with IV gadolinium-based contrast agents may allow functional as well as anatomic assessment. Nuclear cystography has no role in the diagnosis of posterior urethral valves because of the poor anatomic detail, but this modality can depict the presence of vesicoureteral reflux. However, grading of such reflux is not as accurate as with contrast VCUG.

Neutropenic Colitis

13 Year old male patient with ALL with febrile neutropenia showing marke thickening of the ceacum and ascending colon (arrows) suggestive of neutropenic colitis.

Neutropenic colitis, also termed typhlitis or necrotizing enteropathy, is an infectious condition coincident with severe neutropenia. Neutropenic colitis occurs as a complication of acute leukemia, aplastic anemia, or cyclic neutropenia. The cecum is most commonly involved, but the remaining colon and distal ileum also may be affected. Typical clinical features of neutropenic colitis are fever, watery diarrhea, abdominal pain, and occasionally a palpable mass. Recovery is correlated with remission of the underlying disease and return of adequate numbers of functioning neutrophils. Laparotomy and bowel resection is best avoided, unless gross perforation has occurred.

Plain radiographic findings of neutropenic colitis typically consist of right lower abdominal mass density surrounded by paralytic ileus or, rarely, obstruction. These findings are nonspecific and may mimic appendicitis. Barium enema studies are characterized by a thick-walled, poorly distensible cecum with thumb printing and transverse ridging. However, contrast studies are often avoided during episodes of suspected neutropenic colitis because of the danger of perforation and sepsis. The value of sonography for diagnosing neutropenic colitis has not been established; sonography may demonstrate cecal wall thickening, but presence of a pericecal paralytic ileus might impair sonographic results in some instances.

On CT scan there will be diffuse concentric ceacal wall thickeningThe thickened cecum will be isodense to surrounding normal bowel or contained intramural low-density areas consistent with edema, hemorrhage or necrosis, or pneumatosis. A mild paralytic ileus is often associated with neutropenic colitis. Decrease in cecal wall thickening coincided with recovery from neutropenic colitis.

Differential diagnosis of cecal wall thickening associated with neutropenic colitis includes lymphomatous or leukemic intramural deposits and hemorrhage. Lymphomas and leukemia often occur simultaneously, and both diseases may involve the bowel wall. Intramural hemorrhage and lymphomatous or leukemic deposits present as focal eccentric rather than diffuse bowel wall thickening. An abscess related to appendicitis and neutropenic colitis may exhibit similar clinical presentation. Appendicitis is a rare and deadly complication of acute leukemia and has been linked to drug toxicity. On CT, a periappendiceal abscess usually appears as a low-density mass with sharp or irregular margin. An enhancing rim or intrinsic air bubbles may be observed. Cecal wall thickening, however, is not an expected CT finding in appendicitis.


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