Radiation-induced plexopathy and fibrosis. Is magnetic resonance imaging the adequate diagnostic tool?

PURPOSE: To investigate magnetic resonance imaging (MRI) features of radiation-induced plexopathy (RIP) and radiation-induced fibrosis frequently associated with RIP. PATIENTS AND METHODS: Seven patients with late radiation sequelae in the supraclavicular region were examined with MRI after a median interval of 7 years (range, 5-18 years) following radiotherapy and 4-7 years after the onset of RIP. Four patients had RIP plus severe soft-tissue fibrosis, two RIP without soft-tissue fibrosis (n = 2/6), and one patient fibrosis without RIP. Patients underwent surgery of breast cancer (n = 6) or chest wall relapse (n = 1) and radiotherapy to the supraclavicular fossa with cobalt with an anterior portal in fractions of 1.7-2.6 Gy to 43-51.6 Gy in 3 cm depth. All patients were relapse-free at the time of MRI. Fibrosis and RIP were scored clinically (RTOG classification). Fibrosis of the supraclavicular and/or axillary region was marked in three and mild in two patients. RIP was mild, marked and severe in two patients each. MRI was performed with a 1.5-T unit including coronal STIR, coronal and transversal T2-weighted, transversal T1-weighted and fat-saturated post-contrast (gadolinium-DTPA) spin echo sequences. RESULTS: The brachial plexus appeared normal in all patients, but subtle changes of adjoining tissue (slight, linear signal intensity in T2-weighted images or contrast enhancement surrounding the plexus) were detected in patients with RIP (n = 4/6) and the patient without RIP (n = 1). However, alterations of the soft tissue (marked signal intensity in T2-weighted sequences) correlated well with the clinical degree of fibrosis and were restricted to areas of marked to severe fibrosis (n = 3/3). CONCLUSION: Reliable MRI signs of RIP could not be identified. The severity of fibrosis closely corresponded to MRI features. The role of MRI in the diagnostic work-up of RIP is, therefore, the exclusion of tumor relapse.

Individual radiosensitivity measured with lymphocytes may be used to predict the risk of fibrosis after radiotherapy for breast cancer.

BACKGROUND AND PURPOSE: To analyse the relationship of individual cellular radiosensitivity and fibrosis after breast conserving therapy. A new model was used describing the percentage of patients developing fibrosis per year and per patient at risk. PATIENTS AND METHODS: In a retrospective study, 86 patients were included, who had undergone breast conserving surgery and irradiation of the breast with a median dose of 55 Gy (54-55 Gy) given at 2.5 Gy/fraction (n=57) or 2 Gy/fraction (n=29). Median age was 62 years (range 44-86) and median follow-up was 7.5 years (range 5-17). Patients were examined for fibrosis according to the LENT/SOMA score. For analysis, fibrosis was classified as grade 0 and grade 1 (G0-1) or present grade 2 and grade 3 (G2-3). The time to complete development of fibrosis was determined by analysis of yearly mammograms. Individual cellular radiosensitivity was determined by scoring lethal chromosomal aberrations in in vitro irradiated (6 Gy) lymphocytes using metaphase technique. Patients with low/intermediate cellular radiosensitivity were compared with patients with high cellular radiosensitivity using actuarial methods. RESULTS: Ten patients developed fibrosis at 1-8 years after radiotherapy. Individual cellular radiosensitivity was described by normal distribution of lethal chromosomal aberrations, the average was 5.47 lethal aberrations per cell (standard deviation (SD) 0.71). Cellular radiosensitivity was defined as low/intermediate (< or =6.18 lethal aberrations) in 73 patients and high (>6.18 lethal aberrations; mean+SD) in 13 patients. In both groups, the actuarial rate of fibrosis-free patients decreased exponentially with time after radiotherapy. Patients with high cellular radiosensitivity showed a 2.3-fold higher annual rate for fibrosis than patients with intermediate and low radiosensitivity (3.6 versus 1.6% per year). CONCLUSIONS: In breast cancer patients, high individual cellular radiosensitivity as determined by the number of lethal chromosome aberrations in in vitro irradiated lymphocytes might be associated with an enhanced annual rate of fibrosis.

Evaluation of the deep venous system in patients with suspected pulmonary embolism with multi-detector CT: a prospective study in comparison to Doppler sonography.

OBJECTIVE: This prospective study was done to evaluate the ability of indirect multidetector row CT venography (CTV) in detecting deep venous thrombosis of the pelvis and the thighs in comparison with Doppler sonography in patients with suspected pulmonary embolism (PE). METHODS: Forty-one patients with suspected PE were included, and CTV (collimation 4 x 2.5 mm, table feed 12.5 mm, 120 kV, eff. mAs 165) from the iliac crest to the knees was done after CT angiography (CTA) of the pulmonary arteries. Doppler sonography was performed within 24 hours. Applied radiation doses were estimated using the PC program WinDose. RESULTS: PE was diagnosed in 20 patients with additional DVT in 11 patients. The CTV has a sensitivity of 100%, specificity of 96.6%, a positive and negative predictive value of 91.7% and 100%, respectively. The median cumulative effective dose for CTV was 8.26 mSv with a gonadal dose of 3.87 mSv. Changing the CTV protocol to a collimation of 4 x 5 mm with a 25 mm table feed could reduce the dose by approximately 11% (p < 0.05) to 7.25 mSv and 3.35 mSv, respectively. CONCLUSION: CTV is a safe and quick diagnostic tool for detecting DVT in patients with suspected PE. Due to the relevant increase in radiation dose, the indication has to be considered very carefully.