Cerebral Venous Sinus Thrombosis (CVST)

Figure 1: Axial image of the brain shows ill-defined areas of hypoattenuation (stars) in bilateral frontal lobes involving both gray and white matter, in a nonarterial distribution.

Figure 2: A lateral view of CT venography shows occluded anterior 1/3 of the superior sagittal sinus (arrows).

Facts

• 0.5% of all strokes
• Peak incidence in neonates and adults in third decade of life (female:male = 5:1.5)
• Clinical presentation varies widely from relatively mild symptoms to devastating hemorrhage
• Risk factors following Virchow's triad: blood stasis, changes in vessel wall, and changes in blood composition
• Intravenous heparin and subcutaneous low-molecular-weight heparin are primary Rx for acute CVST. Hemorrhage does not preclude the diagnosis.
• Patient prognosis depends on location of CVST (best if in cortical vein, anterior superior sagittal sinus, isolated transverse and isolated sigmoid sinus) and extent of involvement (the more segments of veins involved, the greater complications)

Imaging

• Infarction or hemorrhagic infarction in non-arterial distribution
• Delta sign = filling defect (clot) surrounded by enhanced venous blood in the affected sinus and dural enhancement
• MRI shows T1 hyperintensity and lack of flow void
• Look for potential etiology (and vice versa): paranasal sinus and mastoid infection

References

1. Qureshi AI. Textbook of interventional neurology. 2011

2. Castillo M. Neuroradiology companion: methods, guidelines and imaging fundamentals. 2006

3. Zubkov AY, McBane RD, Brown D, Rabinstein AA. Brain lesions in cerebral venous sinus thrombosis. Stroke 2009;40:1509

Tibial Plateau Fracture

An AP knee radiograph shows a fracture of the lateral tibial plateau (arrows) in an osteopenic patient who had a recent trauma.

Facts

• Fractures involving the articular surface of the proximal tibia. This is a diverse group of fractures, a spectrum of different severity of injuries
• Most common mechanism of injury is fall with knee forced into valgus or varus
• Imaging performed to locate the fracture, identify fracture pattern and degrees of displacement
• Most common location = lateral tibial plateau
• Aim of surgical treatment is to restore or preserve limb alignment

Imaging

• Usually AP and lateral views of the knee show the fracture but bilateral oblique views are also recommended since many subtle joint impaction or fracture lines are not visible on the two views.
• CT with reformations is a study of choice to delineate the extent, orientation of condyle, location and depth of articular comminution and impaction
• Schatzker classification divides tibial plateau fractures into 6 types: lateral plateau without depression, lateral plateau with depression, lateral or central plateau compression, medial plateau, bicondylar plateau, plateau fracture with diaphyseal discontinuity.
• Based on the classification, the management is different. The first three: repair the articular cartilage. The latter three: treatment depends on location of soft tissue injury.

Reference:

Markhardt BK, Gross JM, Monu J. Schatzer classification of tibial plateau fractures: use of CT and MR imaging improves assessment. RadioGraphics 2009

Acute Sinusitis

Water's view radiograph of the paranasal sinus shows an air fluid level in the left maxillary sinus (arrows) of a 56-year-old man.

Facts:

• Very common disease encountered by primary care physicians.
• Diagnostic imaging is generally used in cases of recurrent or complicated sinus disease.
• Plain radiography has a limited role in management of sinusitis

Imaging

• Mucosal thickening, air-fluid levels, complete opacification of the involved sinus
• Mucosal thickening seen in more than 90% of sinusitis case, but very nonspecific
• More specific = air-fluid levels and complete opacification -- but seen in only 60% of cases
• Interpretation can vary widely among observers, with a high rate of false-negative results
• Radiography is not useful in patients younger than 3 years because of poorly developed sinuses
• Because clinical judgment is sufficient to diagnose sinusitis in majority of cases, and empiric treatments are inexpensive and safe --- x-ray should be reserved for patients with persistent symptoms despite appropriate treatment.

Reference:

Okuyemi KS, Tsue TT. Radiologic imaging in the management of sinusitis. Am Fam Physician 2002; 15;66:1882-1887

Acute Sigmoid Diverticulitis

Axial CT image demonstrates left colonic wall thickening, pericolonic fat stranding, fascial thickening (arrowheads) and an inflamed diverticulum (arrow).

Facts: Acute Diverticulitis

• Diverticular disease found in 5-10% of people over the age of 45 years, and 80% by the age of 80
• Diverticulitis is the most common complication of diverticular disease. It is found in 10-25% of people with diverticular disease at some point.
• Most common site of diverticulitis = rectosigmoid colon
• Diagnosis made on a basis of clinical history (pain, fever, diarrhea), examination (abdominal tenderness, palpable mass), lab (elevated inflammatory markers, leucocytosis) and imaging.

Imaging

• CT is considered the best imaging method for diagnosing diverticulitis and characterizing its complications
• CT findings: diverticula, inflamed diverticula, pericolic fat stranding, colonic wall thickening, phlegmon, abscess, extraluminal air
• Differentiating acute diverticulitis from malignancy can be a problem since many findings overlap. Suspicion for malignancy is high if there are pericolonic lymph nodes and the involved segment is short and eccentric.

Reference:

Buckley O, Geoghegan T, O'Riordain DS, et al. Computed tomography in the imaging of colonic diverticulitis. Clin Radiol 2004; 59:977-983.

Anaplastic Astrocytoma

Axial T2W (fig. 1) and T1W post contrast (fig. 2) images of the brain demonstrate a large ill-defined mass (arrows) centered in the right insula with extension to the frontal and temporal lobes. The mass shows a heterogeneous high T2 signal intensity, cystic areas (arrowheads), mass effect and minimal enhancement.

Facts: WHO grading system for primary astrocytic tumor and imaging features

• Grade I = circumscribed glioma including pilocytic astrocytoma -- no mass effect, no enhancement
• Grade II = diffuse astrocytoma (cytological atypia alone) -- mass effect, no enhancement
• Grade III = anaplastic astrocytoma (anaplasia and mitotic activity) -- complex enhancement
• Grade IV = glioblastoma (also show microvascular proliferation) -- necrosis (ring enhancement)

Imaging

• Imaging grading is imprecise but can be used as a preliminary assessment
• Grading is not applicable to pediatric patients or special astrocytomas
• Low grade gliomas usually hypodense on CT, hypointense on T1WI and hyperintense on T2WI. High T2 signal intensity commonly extends beyond the tumor volume. Most do not enhance.
• Anaplastic gliomas may or may not enhance. Calcifications and cysts occur in 10-20%.
• Glioblastomas usually enhance on the rim, representing cellular tumor but tumor cells often extend beyond 1.5 cm of the enhanced ring. Nonenhancing center may represent necrosis or associated cyst.
• On imaging, factors affecting prognosis are location (eloquent vs. non-eloquent) and tumor size

Our case: anaplastic astrocytoma.

Reference:

Greenburg MS. Handbook of neurosurgery, 7th edition, 2010.