Sclerotherapy for Treatment of Anuerysmal Bone Cysts

Aneurysmal bone cysts (ABCs) are benign expansile lytic bone lesions of unknown origin that occur in the pediatric population. Characteristics of ABCs were previously discussed here.

Typically, the treatment of ABCs involves resection and curettage with or without bone grafting. However, there is a high recurrence rate reported with this treatment method with some studies reporting up to a recurrence rate of greater than 50%.

Surgical resection of ABCs is less favored as an extensive resection may be necessary and may immobilize the patient for a prolonged period. Furthermore, as ABCs are highly vascular lesions, surgical procedures carry the risk of significant blood loss.

Radiotherapy was previously used to treat ABCs but has since been abandoned due to studies demonstrating malignant transformation of the lesions and development of secondary tumors.

The traditional interventional radiology technique of embolization has been used effectively in the treatment of some ABCs. Preoperative selective embolization of the feeding vessel is used to reduce intraoperative blood loss as well as to treat lesions that are surgically inaccessible. Challenges of this therapy include risk of particle embolization to the vertebrobasilar and spinal arterial systems resulting in ischemia to vital structures. Additionally, not all ABCs have a feeding vessel that can be selectively embolized. 

More recently, studies have shown intralesional sclerotherapy to be an effective treatment for ABCs. Sclerosing agents act by damaging the endothelial lining which leads to activation of the coagulation cascade and thrombotic vascular occlusion. Agents that have been used for sclerotherapy include ethanol based solutions, methylprednisone, calcitonin, and doxycycline. Patients usually require several injections of the agent. Post procedure imaging typically shows sclerosis of the lesion with long term complete ossification. Patients have reported a relief of symptoms and low recurrence rates have been reported. This data suggests that image guided sclerotherapy of ABCs may be a safe, minimally invasive method of treating these lesions. 



REFERENCES
Rai AT and Collins JJ. Percutaneous treatment of pediatric aneurysmal bone cyst at C1: a minimally invasive alternative: a case report. AJNR Am J Neuroradiol 2005;26:30-3.
Rastogi S, Varshney MK, Trikha V, et al. Treatment of aneurysmal bone cysts with percutaneous sclerotherapy using polidocanol. J Bone Joint Surg [Br] 2006;88-B:1212-6.

Epiploic Appendagitis

Epiploic appendages are peritoneal outpouchings attached to the serosal surface of the colon that contain fat and blood vessels. They occur anywhere from the cecum to the sigmoid, are largest in the sigmoid, and are generally only visible when they are inflamed (i.e. if surrounded by ascites). Torsion of an epiploic appendage or thrombosis of its central vein causes epiploic appendagitis. 

Patients typically present with acute abdominal pain, usually in the left lower quadrant which often leads to its being mistaken for acute diverticulitis (it may be mistaken for acute appendicitis if a cecal epiploic appendage is involved).

CECT will demonstrate an ovoid, fat containing mass adjacent to the anterior colonic wall. Surrounding inflammatory changes are typically seen. A hyperattenuating ring around the mass may be seen. The central dot sign - presence of central high attenuation representing the thrombosed vein - is seen in a minority of cases. Reactive thickening of the adjacent colon may be seen.

The above images are from a patient who presented to the emergency room and was worked up for acute diverticulitis. No colonic diverticula were seen. Instead, in the left lower quadrant there is an ovoid, fat containing mass with inflammatory changes and the central dot sign (arrow). The findings are compatible with epiploic appendagitis.


REFERENCES
Rao PM and Novelline RA. Primary epiploic appendagitis. Radiology 1999;210:145-8.
Singh AK, Gervais DA, Hahn PF, et al. Acute epiploic eppendagitis. Radiographics 2005;25:1521-34.

Phantom Calyx

A phantom renal calyx refers to a calyx that does not opacify after administration of contrast due to obstruction or stricture at the infundibulum. The differential diagnosis for this finding includes:

• neoplasm - most likely transitional cell carcinoma
• infection - tuberculosis, acute pyelonephritis
• stricture - due to trauma or passage of stone
• renal contusion
• ischemia/renal infarct
• congenital anomaly

REFERENCES
Dyer RB, Chen MY, Zagoria RJ. Classic signs in uroradiology. Radiographics 2004;24:S247-80.

Traumatic Aortic Transection

The above images are from a patient who suffered a motor vehicle accident. The axial image demonstrates a mediastinal hematoma and an intimal flap in both the ascending and descending aorta. The sagittal image better demonstrates the continuity of the intimal flap along with aortic contour abnormality. These findings are pathognomonic for acute traumatic aortic injury.

A finding that is not demonstrated on these images is active extravasation of intravenous contrast material. Its presence would be concerning for exsanguination. 


REFERENCES
Kuhlman JE, Pozniak MA, Collins JC, et al. Radiographic and CT findings of blunt chest trauma: aortic injuries and looking beyond them. Radiographics 1998;18:1085-1106.
Steenburg SD, Ravenel JG, Ikonomidis JS, et al. Acute traumatic aortic injury: imaging evaluation and management. Radiology 2008;248:748-62.

Cervical Spine Change in Rheumatoid Arthritis

60-80% of patients with rheumatoid arthritis have cervical spine involvement. Manifestations include:

• atlantoaxial subluxation - do flexion/extension films, increased atlantodens interval
• multilevel, "stepladder" subluxations may be seen
• erosion of the dens
• calcified pannus around the dens is NOT rheumatoid arthritis - usually CPPD
• cranial settling - decreased distance from occiput to C2
• due to facet joint erosions
• spinous process erosions
• erosions at the foramen of Luschka

REFERENCES 
Sommer OJ, Kladosek A, Weiler V, et al. Rheumatoid arthritis: a practical guide to state-of-the-art imaging, image interpretation, and clinical implications. Radiographics 2005;25:381-98.

Dural Sinus Thrombosis

Dural sinus thrombosis (DST) is a venous occlusion likely secondary to increased intracerebral venous pressure. The classic sign on NCECT is hyperdense thrombus in the occluded sinus. CECT may demonstrate the empty delta sign: a filling defect that represents the thrombus surrounding by dural enhancement and collateral venous circulation. The MRI findings in DST are discussed here.

The first two images above demonstrate hyperdensity in superior sagittal sinus and torcular herophili. A left temporal lobe intraparenchymal hemorrhage is also noted. CT venogram (third image) demonstrates abrupt cut off at the level of the mid sagittal sinus that continues posteriorly. 

REFERENCES

Leach JL, Fortuna RB, Jones BV, et al. Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls. Radiographics 2006;26:S19-41.

Sequelae of Tuberculous Pleural Disease

Tuberculosis can have varied presentations in the chest including pleural effusions. Tuberculous pleuritis has a high incidence in immunosuppressed patients, especially those with HIV. Complications of tuberculous pleural disease include:

• pleural thickening
• fibrothorax - calcified and thickened pleura, loss of lung volume, adjacent rib hypertrophy, epipleural fat pads, often unilateral
• chronic persistent pleural effusion - content of the effusion are near soft tissue density
• empyema necessitans - decompression of an empyema through the chest wall, fistulous tract between a pleural collection and an extrathoracic fluid collection may be seen, other sites of extension include breast, esophagus, pericardium, vertebral column, retroperitoneum, flank, groin
• bronchopleural fistula - air/fluid collections in the pleural space, pleural thickening, atelectasis and bronchiectasis in ipsilateral lung, fistulous connection may be seen

REFERENCES

Heffner JE, Klein JS, Hampson C. Diagnostic utility and clinical application of imaging for pleural space infections. Chest 2010;137(2):467-79.

Jung-Ah C, Hong KT, Oh YW, et al. CT manifestations of late sequelae in patients with tuberculous pleuritis. AJR Am J Roentgenol 2001;176(2)441-5.