CONTRIBUTION OF MRI IN THE DIAGNOSIS OF MUSCLE HEMANGIOMA

1. CONTRIBUTION OF MRI IN THE DIAGNOSIS OF MUSCLE HEMANGIOMA Bouaziz.I, Abdelkefi.M , Guermazi Y , Haddar S, Kobbi I, Abid H , Ben Mahfoudh KH , Mnif J Radiology department,CHUHabibBourguiba,Sfax MK3

2. OBJECTIVE: The purpose of this study was to determine whether MR imaging features can suggest the diagnostic of muscular hemangiomas.

3. MATERIALS AND METHODS: We reviewed MR imaging studies of 2 patients aged 18 and 25, explored for a soft-tissue mass. Masses were evaluated for signal intensity on T1 and T2 weighted images, for enhancement with gadolinium administration, and for morphology (lobulation, septation, central low-intensity dots).

4. Case 1: • 30 old patient . • Knee pain.

5. T1 T2 T2 FAT SAT • On T1:low-to-intermediate signal intensity ,lobulated mass with peripheral high signal intensity due to fat overgrowth. • On T2: areas of high signal intensity due to vascular tissue and intermediate signal intensity due to fat. • Intense and homogenous enhancement T1 FAT SAT GADO

6. Case 2: • 25 old patient. • post traumatic pain in the left calf. • Ultrasound: hyperechoic, hetregenous and vascularized, oval mass, of the gastrocnemiusleft muscle.

7. oval mass, of the gastrocnemius muscle,hypointense on all sequences. • Accentuated hypointensity in the periphery ,in relation with a deposit of hemosiderin. • T2 hyperintensity in the center, with gradually enhancement after gadolinium injection, in connection with intralesional venous maze. • It is surrounded by a peripheral hyperintensity in T1 and T2 canceled in fat sat. T1 T2 T1 FAT SAT GADO T1

8. DISCUSSION • Soft-tissue hemangiomas are common neoplasms of benign histologic origin. • They are the most common of the angiomatous lesions and represent up to 7% of all benign soft-tissue tumors in the general population . • Women are more often affected than men. • Hemangiomas are the most frequently diagnosed soft-tissue neoplasm in children.

9. Histologically, soft-tissue hemangiomas are subdivided into five categories, depending on the predominant type of vascular channel identified. • These subdivisions include capillary, cavernous, arteriovenous, venous, and mixed variations .

10. Of these categories, capillary hemangiomas are the most common . • They are usually diagnosed during the first few years of life and are found in the skin, subcutaneous tissue, or vertebral bodies. Microscopically, capillary hemangiomas are composed of a disordered array of capillary-sized vessels. Most of these hemangiomas spontaneously involute .

11. Cavernous hemangiomas are larger and deeper and occur later in life. • They are often intramuscular. • They are composed of dilated, blood-filled spaces lined by flattened endothelium. Calcification is common. • They do not spontaneously involute and therefore may require surgical intervention .

12. Arteriovenoushemangiomas may be deep or superficial. • They represent an abnormal communication between arteries and veins and can cause a variable degree of shunting. The composition of these lesions reflects a persistent fetal capillary bed. • Venous soft-tissue hemangiomas typically involve deep structures and can classically be found in the retroperitoneum, mesentery, and extremities. • Histologically, they are composed of thicker-walled vessels containing smooth muscle cells.

13. The term “haemangioma” is commonly misused to describe any type of vascular abnormality, including vascular malformation.

14. In addition to their vascular components, angiomatous tumors can contain thrombus, calcification, hemosiderin, fat, smooth muscle, and fibrous tissue . • This is particularly true of cavernous hemangiomas. • The most common association is that of reactive fat overgrowth. In fact, overgrowth of adipose tissue can be so prominent that in the past, these lesions were classified as angiolipomas.

15. Venous malformation can occur in every muscle group with pain and swelling being the usual complaints. Vascular malformations are usually present at birth, grows proportionally with the child and never involutes.

16. Intramuscular haemangiomas account for 0.8% of all haemangiomas. • It occurs most commonly in young adults with 80–90% presenting in individuals younger than 30 years. • Clinically they manifest with a mass without any diagnostic features. Pain is a cardinal symptom in 60% of the cases,1 with the lower extremity being the commonest site of involvement. • The quadriceps is the most frequently affected muscle. Intramuscularhaemangiomasprogressivelyenlargebut never metastasize. There is a 9% recurrence rate after surgical excision.

17. Plain radiographs of soft tissue haemangioma may appear only as a non-specific soft tissue mass and in 25–30% of cases it shows phlebolith. • Periosteal reaction adjacent to the haemangioma may mimic osteomylitis or bone tumour.

18. At nonenhanced CT, an ill-defined mass of similar attenuation to muscle may be identified. Phleboliths too small to identify on radiographs can be revealed. After administration of contrast material, significant enhancement is typical. • serpentine vascular structures may be depicted as well as surrounding adipose overgrowth.

19. US can demonstrate a complex mass. If phleboliths are abundant, acoustic shadowing may also be documented . • Doppler evaluation may show low-resistance arterial flow with forward flow during both systole and diastole .

20. Currently, the standard for imaging evaluation of soft-tissue hemangiomas is MR imaging . • MRI is important for further characterization of the substance and extent of the soft tissue haemangioma. • Typically, all sequences show a heterogeneous mass (although lesions measuring under 2 cm tend to be homogeneous), reflecting the mix of tissues present.

21. T1-weighted images best reveal areas of high-signal-intensity adipose tissue, most prominent along the circumference of the vascular complex. This fatty tissue may reflect muscle atrophy secondary to chronic vascular insufficiency caused by the steal phenomenon. • In some patients, the fat overgrowth is so prominent that these lesions are mistaken for lipomas .

22. On T2-weighted images, hemangiomashave been described as having a multilobulatedhigh-signal-intensityconfiguration interspersedwith linear and lacelike areas of low or intermediate signal intensity . • the distinctive septate–lobulated appearance on T2-weighted imaging correlated with fibrous and fatty septa(low signal) between endothelial-lined vascular channels (high signal) identified on histologic examination.

23. The central angiomatous core of the neoplasm shows high signal intensity on T2-weighted images. As on contrast-enhanced CT images, the serpentine nature of the hemangioma may be depicted. • If blood flow through these vascular channels is rapid enough, the signal may remain low in intensity with all MR imaging sequences. If gadolinium contrast material is administered, prominent enhancement of the angiomatous tumor is expected .

24. Characteristic tubular or serpentine components are orientated along the muscular long axis. • Thrombi are hyperintense on T1-weighted and hypointense on T2-weightedsequences

25. Central low-intensity dot sign on T2-weighted imaging in hemangiomas has been described . This sign is highly specific for hemangiomascomparedwithmalignantsoft-tissue masses. • These rounded foci of low signal intensity seen in hemangiomas may represent fibrofattysepta seen in cross section, or hyalinizedor thrombosed vascular channels

26. Fast flow in blood vessels is a likely cause in some cases because the central low-intensity dots disappear after gadolinium administration . • This central low-intensity dot has also been described in benign neurofibromas , where it produces a so-called targetlike appearance. • The pattern of enhancement is helpful in distinguishing between neurofibromas and hemangiomas. Because the central low-intensity dot in benign neurofibromas is caused by dense collagen, it is not likely to exhibit enhancement with gadolinium as hemangiomas do.

27. MRI may help to differentiate between types of haemangiomas. • Lesions with large cystic spaces are cavernous whereas arteriovenoushaemangiomas show more prominent fast flow serpentine vessels. Venous haemangiomas, on the other hand, show slow-flow serpentine vessels.

28. MRI may also help to differentiate between haemangiomas and malignant soft-tissue masses . • The T2 signal intensity of hemangiomas is greater than that of malignant soft-tissue masses. Hemangiomas have high T2 values, which may reflect pooling of the blood within cavernous spaces and slow flow within dilated venous channels • Intense enhancement, is supportive of the diagnosis of hemangioma but should be used in corroboration of other findings to reach the diagnosis.

29. Angiography should be considered if MRI has not provided sufficient information about the relationship between the tumour and a neurovascular bundle. • In patients in whom excision is impractical, embolization or radiotherapy should be considered. In cases of recurrence adjuvant therapy (interferon-) may be considered.

30. CONCLUSION • Morphological caracterisations, signal intensity and enhancement with gadolinium allowed to diagnose muscular hemangiomas and differentiation from other soft-tissue masses