SPLENIC ABSCESS

Axial T1 FS image showing large relatively thick walled fluid collection with debris and air pockets. Note the air fluid level anteriorly

Sagittal T2 Wt image showing the abscess with airfluid level anteriorly- suggests pyogenic abscess.



Axial DWI image showing mild restriction within the abscess.



·        The rarity of primary splenic abscesses is probably related to splenic phagocytic immune functions.

·        A splenic abscess may be bacterial, fungal, or granulomatous.

·        In infants and children, splenic abscesses occur most frequently in immunocompromised patients.

·        Abscesses may be single or multiple.

·        With fungal infections in an immunocompromised patient, abscesses are typically multiple.

·        Pyogenic abscesses can be secondary to underlying sepsis or spread by hematogenous seeding.

·        Amebic dysentery, otitis media, mastoiditis, peritonsillar abscess, cutaneous infection, pneumonia, empyema, appendicitis, osteomyelitis, and intravenous drug abuse are all risk factors.

·        Patients with hemoglobinopathies are also at risk for splenic abscess formation secondary to infarction and necrosis as well as functional asplenia.

·        Pyogenic abscesses manifest as ill-defined, hypoechoic lesions at US. Debris and internal septations may be present. In rare cases, gas bubbles may be seen.

·        If present, intralesional gas is pathognomonic for pyogenic infection.

·        At CT, pyogenic abscesses typically manifest as single, irregularly marginated lesions with low attenuation. Rim enhancement can be seen on contrast enhanced scans.

·        Fungal abscesses are small lesions, typically only a few millimeters in diameter.

·        The most common infecting organisms are Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans.

·        M tuberculosis, M avium intracellulare, and P carinii infection can have similar appearances.

·        Fungal abscesses have a variable appearance at US.

·        Typically, they manifest as rounded, hypoechoic lesions with a central area of increased echogenicity, creating a “target” or “bull's-eye” appearance. These findings correspond to fibrotic tissue surrounding a central inflammatory core at histopathologic analysis.

·        The “wheel-in-a-wheel” appearance is seen when the central hyperechoic portion becomes necrotic and hypoechoic.

·        Hepatosplenomegaly is usually associated with fungal abscesses. CT typically demonstrates multiple small, low-attenuation lesions. The lesions may be missed unless intravenously administered contrast material is used.

·        Reference: A Pattern-oriented Approach to Splenic Imaging in Infants and Children, November 1999 RadioGraphics, 19, 1465-1485.



ANTERIOR ABDOMINAL WALL INCISIONAL HERNIA

Lateral topogram of abdomen revealed herniation of bowel loop through anterior abdominal wall in infraumbilical region. Dilated jejunal loops with multiple airfluid levels.

TYPES OF ABDOMINAL HERNIAS:

1.     Groin hernias

a.      Inguinal

b.     Femoral

2.     Ventral hernias

a.      Umbilical

b.     Paraumbilical

c.      Epigastric

d.     Hypogastric

3.     Lumbar hernias

a.      Superior (Grynflett-Lesshaft)

b.     Inferior (petit)

4.     Incisional

5.     Others

a.      Interparietal

b.     Richter

c.      Litter

d.     Sciatic

e.      Obturator

f.       Perineal

Reference : Abdominal Wall Hernias: Imaging Features, Complications, and Diagnostic Pitfalls at Multi–Detector Row CT, November 2005 RadioGraphics, 25, 1501-1520

CEREBRAL METASTASIS- MULTIPLE RING ENHANCING LESIONS

Axial T2 FLAIR and T1 Wt images show multiple thick walled isointense lesions with central necrosis and surrounding edema, predominantly distributed at the corticomedullary junction.

Axial contrast enhanced T1 Wt images show ring enhancement of all the lesions, with central dot like enhancement in some of them and irregular solid enhancement in the rest. Note the lesion in left sylvian fissure-s/o meningeal deposit.

Axial and Coronal CT of chest revealed large irregular mass lesion in left perihilar region extending into apicoanterior segment with multiple metastatic nodules in the periphery of both lungs- s/o carcinoma lung with metastasis.

·        Primary and metastatic tumors, on imaging, often manifest as rounded, well-circumscribed, ring-enhancing lesions of variable sizes surrounded by a variable amount of perifocal vasogenic edema.

·        Metastatic tumors are the most common intracranial neoplasm in adults.

·        Lung cancer, breast cancer and melanoma account for the majority of patients with metastasis in the brain.

·        The incidence of brain metastases has recently increased because of several factors, including improved survival, better treatment of systemic diseases and improved intracranial imaging techniques.

·        There were no characteristic computed tomography patterns for specific systemic carcinomas, but epidermoid carcinoma frequently appeared as a low-density lesion with a thin peripheral enhancing rim, and adenocarcinoma appeared as a dense, homogeneous, round, enhancing nodule.

·        After treatment, focal cerebral parenchymal enhancement was the most reliable sign of residual or recurrent tumor.

·        Metastatic lesions are typically subcortical, occurring in or near the gray matter-white matter junction, and are usually associated with severe perilesional edema.

·        MRI typically reveals mild T1 hypointensity with T2 hyperintensity and fluid-attenuated inversion recovery hyperintensity at the site of the lesion.

·        After contrast administration, a nodular ring pattern of enhancement is seen.

·        Metastases from malignant melanoma may demonstrate T1 hyperintensity because of hemorrhagic or melanin components of the lesion.

·        Rapidly growing primary brain tumors, such as glioblastoma multiforme or anaplastic astrocytoma, can present with many of the same imaging characteristics as seen in metastatic lesions of the brain.

·        Most of the primary tumors are large in size and are often located deep in the white matter.

·        Primary brain tumors frequently cross the midline. For example, glioblastoma multiforme frequently crosses the midline by infiltrating the white matter tracts of the corpus callosum.

·        Differential diagnosis of multiple ring enhancing lesions of brain:

      Reference : Garg RK, Sinha MK. Multiple ring-enhancing lesions of the brain. J Postgrad Med 2010;56:307-16

view similar cases:
http://radfacts.blogspot.in/2012/06/neurocysticercosis.html

BENNETT'S fracture

Frontal radiograph of left wrist shows fracture base of 1st metacarpal with extension into articular surface. The fracture fragment maintains articulation with trapezium, rest of the metacarpal shows mild displacement laterally.

Rolando Fracture Comminuted Intra-articular Fracture through base of thumb Prognosis: worse than Bennett's fracture (difficult to reduce)

Bennett's Fracture Intra-articular fracture/dislocation of base of 1st metacarpal Small fragment of 1st metacarpal continues to articulate with trapezium Lateral retraction of 1st metacarpal shaft by abductor pollicis longus

BOUTENNIERE DEFORMITY

40 yrs female with inability to extend 3rd finger of left hand following trauma.

Frontal and lateral projections of 3rd finger of left hand showed flexion deformity of proximal interphalangeal joint and extension deformity of distal interphalangeal joint. moderate soft tissue swelling around the proximal phalanx. No evidence of fracture/ avulsion fragment.

High resolution sonography of 3rd finger of left hand revealed rupture of central slip of extensor digitorum tendon at its insersion onto the middle phalanx (1st image. see normal central slip of other finger for comparision). The two lateral slips are intact(2nd image). Axial images of normal and abnormal fingers showing edema at the site of disruption with absent tendon fibres and widely seperated lateral slips(3rd image).

Anatomy:

·        The extensor tendons to the four fingers pass across their respective metacarpophalangeal joints.

·        The deeper fibres of the tendons form the posterior capsule of the joints.

·        The bulk of each tendon passes freely across each joint. 

·        The tendons then broaden out and divide into three slips on the dorsal aspect of each proximal phalanx.

·        The central slip passes on to the base of the middle phalanx. 

·        The lateral slips diverge around the central slip and receive strong attachments from the interossei and lumbricals forming the extensor expansion.

Boutonnière (“button hole”) deformity:

·        Injury to the central tendon results in an imbalance in the extensor mechanism. 

·        Flexor digitorum superficialis is unopposed and it flexes the proximal interphalangeal joint.

·        This forces the head of the proximal phalanx between the lateral bands.

·        With time, the triangular ligament ruptures causing the lateral bands to displace volar to the axis of motion of the proximal interphalangeal joint and become flexors of the joint. 

·        The extensor hood retracts proximally, causing extension at the metacarpophalangeal and distal interphalangeal joints.

·        This results in  flexion of the proximal interphalangeal joint and hyperextension of the distal interphalangeal and metacarpophalangeal joints, known as the boutonnière (“button hole”) deformity.

·        Types of injury:

1.     Avulsion fracture of middle phalanx

2.     Partial rupture with stretching of central slip

3.     Complete rupture with seperation

Reference : Ultrasound imaging of finger tendons at the bedside in the emergency department, Southern Cross University ePublications@SCU.

MIDGUT MALROTATION OF ADULT



Axial CECT of abdomen showing altered relation of SMA and SMV. The duodenal flexure is seen on the right of midline(not shown here). 



volume rendered images of bowel showed transverse orientation of ascending colon with caecum and appendix in right upper quadrant.

VR images of major vessels showed SMA to the right of SMV.

·        Intestinal malrotation can be broadly defined as any deviation from the normal 270° counterclockwise rotation of the midgut during embryologic development.

·        Malrotation results not only in the malposition of the bowel but also in the malfixation of the mesentery.

·        The normally broad mesenteric attachment is shortened to a narrow pedicle that predisposes the patient to the complication of midgut volvulus.

·        Internal hernia related to abnormal peritoneal fibrous bands (of Ladd) that attach to the right colon is another complication of malrotation seen in adults.

·        Conventional radiography is neither sensitive nor specific for malrotation, although right-sided jejunal markings and the absence of a stool-filled colon in the right lower quadrant may be suggestive of this finding.

·        The upper gastrointestinal barium series remains accurate for detection, and the rules familiar to pediatric radiology also apply for adults—that is, the duodenal—jejunal junction fails to cross the midline and lies below the level of the duodenal bulb.

·        An abnormal junction in an adult should not be dismissed as a normal variant.

·        Contrast enema examination usually shows malposition of the right colon, but the cecum may assume a normal location in up to 20% of patients.

·        The contrast enema findings are also nonspecific because cecal location can be variable without malrotation.

·        Many cases of quiescent malrotation in adults are currently being detected on cross-sectional imaging performed for various unrelated reasons.

·        CT not only shows the intestinal malpositioning seen on barium studies but also depicts associated extraintestinal findings not evident on conventional examinations. For example, deviation from the normal relationship between the SMA and SMV is a useful indicator of malrotation.

·        In most patients with quiescent malrotation, the SMA and SMV will assume a vertical relationship or show left—right inversion.

·        Analogous findings can be seen on sonography.

·        Abnormalities of SMA—SMV orientation are not entirely diagnostic, however, because some patients with malrotation will have a normal relationship, and a vertical or inverted relationship can also be seen in patients without malrotation.

·        Therefore, isolated detection of such an abnormality is not sufficient for diagnosis but should warrant closer examination of the bowel.

·        Finally, inspection of the pancreas in malrotation will reveal underdevelopment or absence of the uncinate process.

·        Acute complications of malrotation:

1.     Midgut volvulus

2.     Internal hernia

·        Regardless of patient age, surgical treatment of quiescent malrotation should be considered because surgery remains the only real safeguard against complications.

Reference : Intestinal Malrotation in Adolescents and Adults: Spectrum of Clinical and Imaging Features, AJR December 2002 vol. 179 no. 6 1429-1435.