Percutaneous Computed Tomography-Guided Lung Biopsies using a Virtual Navigation Guidance: Our Experience.

OBJECTIVE: To evaluate the effectiveness of a virtual CT-guided navigation system (Sirio-MASMEC Biomed) in performing lung biopsies, with greater attention to lesions smaller than 1 cm, compared to the traditional procedure. METHODS: This study was approved by the Ethics Committee of our Institute. Two hundred patients were prospectively selected. Of these, 100 were subjected to percutaneous procedure with the use of Sirio and 100 to traditional CT-guided percutaneous procedure. The two methods were compared in terms of absorbed dose, procedure time, complications, and number of non-diagnostic specimens (diagnostic success). RESULTS: Sirio has shown a significant reduction in the absorbed dose and procedure times (p < 0.05), with a lower incidence of complications compared to the traditional procedure. Sirio has also allowed to carry out biopsies of lesions' diameter ≤10 mm, obtaining fewer non diagnostic specimens thus resulting more effective in terms of diagnostic success. CONCLUSIONS: The use of Sirio in sampling biopsy showed a statistically significant reduction in terms of performed scans and procedural time with lower incidence of post-procedural complications compared to the traditional percutaneous procedure, especially for lesions ≤10 mm. The best diagnostic result, the reduction of the dose absorbed and procedural complications makes the procedures more reliable, safety and less invasive. In addition, the reduction of execution time will increase the number of daily interventional procedures improving clinical management.

Can Diffusion-Weighted Imaging and Related Apparent Diffusion Coefficient be a Prognostic Value in Women With Breast Cancer?

PURPOSE: To analyze diffusion-weighted imaging (DWI) and the related apparent diffusion coefficient (ADC) in women with breast cancer, correlating these values with the presence at 3 years of distant metastases, and to demonstrate that DWI-Magnetic Resonance Imaging (MRI) and related ADC values may represent a prognostic value in the study of women with breast cancer. MATERIALS AND METHODS: Sixty women (aged 45-73 years) affected with breast cancer with a follow-up in 3 years were enrolled. On DWI, we obtained the ADC values, and these were correlated with the clinical condition of patients at 3 years. Moreover, tumour size, lymph node status, and molecular markers, including estrogens receptor, progesterone receptor, Ki-67 index, and human growth factor receptor 2 protein, were correlated with ADC values. This study was approved by the Scientific Committee of our institution. RESULTS: We considered patients with metastasis at 3 years (12 patients - 20%) and without metastasis (48 patients - 80%). The mean ADC value in patients with no metastases at 3 years was 1.06 ± 0.38, while for patients with metastases it was 0.74 ± 0.34 (p = .011). The receiver-operator curve analysis identified a value of 0.75 (<0.75 with risk to develop metastasis) as the best predictive cutoff for ADC values, with the highest sensitivity (81.25%) and higher specificity (66.67%). After regression analysis, ADC value, positivity to estrogen-progestin receptors, and presence of lymph nodes were the only prognostic factors found to be statistically significant. CONCLUSIONS: DWI-MRI and related ADC values may represent a prognostic value in women with breast cancer.

Magnetic Resonance Imaging in the Pre-Surgical Staging of Breast Cancer: Our Experience.

PURPOSE: To investigate the clinical impact of magnetic resonance imaging (MRI) in the detection of multifocal-multicentric breast cancers, already identified by mammography and ultrasound, and analyzed histologically, to evaluate its role in preoperative staging. MATERIALS AND METHODS: From January 2012 to February 2014, 188 patients, aged 28 to 74 years, newly diagnosed with breast cancer on conventional imaging (mammography and ultrasound) were enrolled. They underwent preoperative contrast-enhanced 3T MRI. Patients underwent surgery according to international guidelines. Results of all diagnostic procedures were compared. RESULTS: Among the 188 patients, 163 (87%) had a unilateral and unifocal tumor at both conventional imaging; MRI diagnosed 22/22 (100%) of multifocal and multicentric tumors, the combination of mammography and ultrasound diagnosed 12/22 (54%), and mammography alone diagnosed 8/22 (36%) multifocal and multicentric tumors. MRI prompted a change in surgical strategy in 10/188 (5%) patients. This change comprised mastectomy instead of conservative surgery (n = 7) and more extensive conservative surgery (n = 3). CONCLUSIONS: MRI was confirmed to show higher sensitivity than conventional imaging in detecting multifocal and multicentric breast cancers.

Diffusion weighted imaging and apparent diffusion coefficient in 3 tesla magnetic resonance imaging of breast lesions.

OBJECTIVE: To evaluate the utility of diffusion-weighted-imaging (DWI) and apparent-diffusion-coefficient (ADC) in a 3T magnetic-resonance-imaging (MRI) study of breast cancer. In particular, the study aims to classify ADC-values according to histology either for benign or malignant lesions. METHODS: 110 Breast MRI with MRI-DWI sequences and quantitative evaluation of the ADC were retrospectively reviewed. Results obtained with MRI-DWI and with biopsy were analyzed and ADC values were compared to histological results. RESULTS: MRI showed a 95.5% sensitivity and a 83.7% specificity. The mean ADC values of benign and malignant lesions were 2.06 ± 0.19 and 1.03 ± 0.07 mm(2)/s, respectively (p < .05). CONCLUSIONS: DWI and ADC-values could help distinguishing malignant and benign breast masses.

Head and neck intensity modulated radiotherapy parotid glands: time of re-planning.

PURPOSE: To investigate the correct time point for re-planning by evaluating dosimetric changes in the parotid glands (PGs) during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients. MATERIALS AND METHODS: Patients with head and neck cancer treated with IMRT were enrolled. During treatment all patients underwent cone-beam computed tomography (CBCT) scans to verify the set-up. CBCT scans at treatment days 10, 15, 20 and 25 were used to transfer the original plan (CBCTplan I, II, III, IV, respectively) using rigid registration between the two. The PGs were retrospectively contoured and evaluated with the dose-volume histogram. The mean dose, the dose to 50 % of volume, and the percentage of volume receiving 30 and 50 Gy were evaluated for each PG. The Wilcoxon sign ranked test was used to evaluate the effects of dosimetric variations and values <0.05 were taken to be significant. RESULTS: From February to June 2011, ten patients were enrolled and five IMRT plans were evaluated for each patient. All the dosimetric parameters increased throughout the treatment course. However, this increase was statistically significant at treatment days 10 and 15 (CBCTplan I, II; p = 0.02, p = 0.03, respectively). CONCLUSION: CBCT is a feasible method to assess the dosimetric changes in the PGs. Our data showed that checking the PG volume and dose could be indicated during the third week of treatment.

Comparison between Gleason score and apparent diffusion coefficient obtained from diffusion-weighted imaging of prostate cancer patients.

OBJECTIVES: To correlate the apparent diffusion coefficient (ADC) of prostate cancer patients with pathological Gleason scores (GS). METHODS: 40 patients with GS 2 + 3, 3 + 3, 3 + 4, or 4 + 4 were selected. The magnetic resonance imaging (MRI) study was performed adding axial diffusion-weighted imaging (DWI) sequences to the standard MRI protocol. ADC values obtained were correlated with the GS data. RESULTS: Statistically significant differences of ADC (p < .05) were found among GS groups with a trend of decreasing ADC values with increasing GS. CONCLUSIONS: The ADC values may help clinicians to delineate prostate carcinoma, recognizing its high- or low-grade compartments.

Monitor unit optimization in RapidArc plans for prostate cancer.

Intensity-modulated radiation therapy (IMRT) has become a standard treatment for prostate cancer based on the superior sparing of the bladder, rectum, and other surrounding normal tissues compared to three-dimensional conformal radiotherapy, despite the longer delivery time and the increased number of monitor units (MU). The novel RapidArc technique represents a further step forward because of the lower number of MUs per fraction and the shorter delivery time, compared to IMRT. This paper refers to MU optimization in RA plans for prostate cancer, using a tool incorporated in Varian TPS Eclipse. The goal was to get the lowest MU RA plan for each patient, keeping a well-defined level of PTV coverage and OAR sparing. Seven prostate RA plans (RA MU-Optimized) were retrospectively generated using the MU optimization tool in Varian Eclipse TPS. Dosimetric outcome and nontarget tissue sparing were, compared to those of RA clinical plans (RA Clinical) used to treat patients. Compared to RA Clinical, RA MU-Optimized plans resulted in an about 28% (p = 0.018) reduction in MU. The total integral dose (ID) to each nontarget tissue (but not the penile bulb) showed a consistent average relative reduction, statistically significant only for the femoral heads. Within the intermediate dose region (40-60 Gy), ID reductions (4%-17% p < 0.05) were found for the rectum, while a slight but significant (0.4%-0.9%, p < 0.05) higher ID was found for the whole body. Among the remaining data, the mean dose to the bladder was also reduced (-12%, p = 0.028). Plans using MU optimization are clinically applicable and more MU efficient, ameliorating the exposure of the rectum and the bladder to intermediate doses.

Local tumor control probability to evaluate an applicator-guided volumetric-modulated arc therapy solution as alternative of 3D brachytherapy for the treatment of the vaginal vault in patients affected by gynecological cancer.

The purpose of this study was to evaluate the applicator-guided volumetric-modulated arc therapy (AGVMAT) solution as an alternative to high-dose-rate brachytherapy (HDR-BRT) treatment of the vaginal vault in patients with gynecological cancer (GC). AGVMAT plans for 51 women were developed. The volumetric scans used for plans were obtained with an implanted CT-compatible vaginal cylinder which provides spatial registration and immobilization of the gynecologic organs. Dosimetric and radiobiological comparisons for planning target volume (PTV) and organs at risk (OARs) were performed by means of a dose-volume histogram (DVH), equivalent uniform dose (EUD), and local tumor control probability (LTCP). In addition, the integral dose and the overall delivery time, were evaluated. The HDR-BRT averages of EUD and minimum LTCP were significantly higher than those of AGVMAT. Doses for the OARs were comparable for the bladder and sigmoid, while, although HDR-BRT was able to better spare the bowel, AGVMAT provided a significant reduction of d2cc, d1cc, and dmax (p < 0.01) for the rectum. AGVMAT integral doses were higher than HDR-BRT with low values in both cases. Delivery times were about two or three times higher for HDR-BRT with respect to the single arc technique (AGVMAT1) and dual arc technique (AGVMAT2), respectively. The applicator-guided volumetric-modulated arc therapy seems to have the potential of improving rectum avoidance. However, brachytherapy improves performance in terms of PTV coverage, as demonstrated by a greater EUD and better LTCP curves.

Impact of comorbidity in elderly prostate cancer patients treated with brachytherapy.

OBJECTIVE: To analyze the correlations among comorbidity and overall survival (OS), biochemical progression-free survival (b-PFS) and toxicity in elderly patients with localized prostate cancer treated with (125)I brachytherapy. METHODS: Elderly men, aged ≥65 years, with low-intermediate risk prostate cancer, were treated with permanent (125)I brachytherapy as monotherapy. Comorbidity data were obtained from medical reports using age-adjusted Charlson comorbidity index (a-CCI). The patients were categorized into two age groups (<75 and ≥75 years old), and two comorbidity score groups (a-CCI ≤3 and >3). Toxicity was scored with Radiation Therapy Oncology Group (RTOG) scale. RESULTS: From June 2003 to October 2009, a total of 92 elderly patients underwent prostate brachytherapy, including 57 men (62%) with low-risk prostate cancer, and 35 men (38%) with intermediate-risk prostate cancer. The median age of patients was 75 years (range, 65-87 years). Forty-seven patients (51%) had a-CCI ≤3 and 45 patients (49%) a-CCI >3. With a median follow-up period of 56 months (range, 24-103 months), the 5-year actuarial OS and b-PFS were 91.3% and 92.4% respectively, without statistical significance between two Charlson score groups. Toxicity was mild. None of the patients experienced gastrointestinal (GI) toxicity, and only 4 patiens (4%) experienced late genitourinary (GU) grade-3 (G3) toxicity. No correlation between acute GU and GI toxicity and comorbidity was showed (P=0.50 and P=0.70, respectively). CONCLUSIONS: Our data suggest that elderly men with low-intermediate risk prostate cancer and comorbidity can be considered for a radical treatment as (125)I low-dose rate brachytherapy.

Modelling the correlation between EGFr expression and tumour cell radiosensitivity, and combined treatments of radiation and monoclonal antibody EGFr inhibitors.

PURPOSE: To estimate the effects of heterogeneity on tumour cell sensitivity to radiotherapy combined with radiosensitizing agents attributable to differences in expression levels of Epidermal Growth Factor Receptor (EGFr). MATERIALS AND METHODS: Differences in radiosensitivity are not limited to cells of different cancer histotypes but also occur within the same cancer, or appear during radiotherapy if radiosensitizing drugs are combined with ionizing radiation. A modified biologically effective dose (MBED), has been introduced to account for changes in radiosensitivity parameters (α and α/ß) rather than changes in dose/fraction or total dose as normally done with standard biologically effective dose (BED). The MBED approach was applied to cases of EGFr over-expression and cases where EGFr inhibitors were combined with radiation. Representative examples in clinical practice were considered. RESULTS: Assuming membrane EGFr over-expression corresponds to reduced radiosensitivity (α(H) = 0.15 Gy(-1) and α(H)/ß(H) = 7.5 Gy) relative to normal radiosensitivity (α = 0.2 Gy(-1) and α/ß = 10 Gy), an increased dose per fraction of 2.42 Gy was obtained through the application of MBED, which is equivalent to the effect of a reference schedule with 30 fractions of 2 Gy. An equivalent hypo-fractionated regime with a dose per fraction of 2.80 Gy is obtained if 25 fractions are set. Dose fractionations modulated according to drug pharmacokinetics are estimated for combined treatments with biological drugs. Soft and strong modulated equivalent hypo-fractionations result from subtraction of 5 or 10 fractions, respectively. CONCLUSIONS: During this computational study, a new radiobiological tool has been introduced. The MBED allows the required dose per fraction to be estimated when tumour radiosensitivity is reduced because EGFr is over-expressed. If radiotherapy treatment is combined with EGFr inhibitors, MBED suggests new treatment strategies, with schedules modulated according to drug pharmacokinetics.

Radiotherapy and bevacizumab for intramedullary and leptomenigeal metastatic glioblastoma: a case report and review of the literature.

Glioblastoma (GBM) developed metastases rarely and the prognosis, in these cases, was very poor. We reported a 30-year patient who, developing intramedullary and leptomeningeal metastases from GBM, underwent palliative spinal radiotherapy (RT) and Bevacizumab.

On the dependence of quantitative diffusion-weighted imaging on scanner system characteristics and acquisition parameters: A large multicenter and multiparametric phantom study with unsupervised clustering analysis.

PURPOSE: The purpose of this multicenter phantom study was to exploit an innovative approach, based on an extensive acquisition protocol and unsupervised clustering analysis, in order to assess any potential bias in apparent diffusion coefficient (ADC) estimation due to different scanner characteristics. Moreover, we aimed at assessing, for the first time, any effect of acquisition plan/phase encoding direction on ADC estimation. METHODS: Water phantom acquisitions were carried out on 39 scanners. DWI acquisitions (b-value = 0-200-400-600-800-1000 s/mm2) with different acquisition plans (axial, coronal, sagittal) and phase encoding directions (anterior/posterior and right/left, for the axial acquisition plan), for 3 orthogonal diffusion weighting gradient directions, were performed. For each acquisition setup, ADC values were measured in-center and off-center (6 different positions), resulting in an entire dataset of 84 × 39 = 3276 ADC values. Spatial uniformity of ADC maps was assessed by means of the percentage difference between off-center and in-center ADC values (Δ). RESULTS: No significant dependence of in-center ADC values on acquisition plan/phase encoding direction was found. Ward unsupervised clustering analysis showed 3 distinct clusters of scanners and an association between Δ-values and manufacturer/model, whereas no association between Δ-values and maximum gradient strength, slew rate or static magnetic field strength was revealed. Several acquisition setups showed significant differences among groups, indicating the introduction of different biases in ADC estimation. CONCLUSIONS: Unsupervised clustering analysis of DWI data, obtained from several scanners using an extensive acquisition protocol, allows to reveal an association between measured ADC values and manufacturer/model of scanner, as well as to identify suboptimal DWI acquisition setups for accurate ADC estimation.

The Role of Adjuvant Radiotherapy for a Case of Primary Breast Sarcoma: A Plan Comparison between Three Modern Techniques and a Review of the Literature.

A 65-year-old woman, affected by a malignant fibrous histiocytoma (undifferentiated pleomorphic sarcoma) of the left breast, presented to our department to receive the postoperative radiotherapy. In the absence of prospective and randomized trials and investigations on breast sarcoma irradiation in literature, due to the rarity of this pathology, the role of adjuvant radiotherapy remains unclear. To identify the best radiotherapy technique for this patient, three methods were compared: 3D conformal radiotherapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and volumetric arc therapy (VMAT) or RapidArc® (RA). 50 Gy was prescribed to the chest wall and 66 Gy to the tumor bed. Three plans were designed, and target coverage, organs-at-risk sparing, and treatment efficiency were compared. IMRT and RA improved both target coverage and dose uniformity/homogeneity. Planning objective for the lung is always satisfied comparing the different techniques, but the volume receiving 20 Gy drops to 17% by RA compared to 3D-CRT. The heart volume receiving 30 Gy was 10% by IMRT, against 13% and 16% by RA and 3D-CRT. The monitor unit (MU) required by 3D-CRT was 527 MU, followed by RA and IMRT. Treatment time was similar with 3D-CRT and RA but doubled using IMRT. Although all three radiotherapy techniques offered a satisfactory solution, RA and IMRT offer some improvement on target coverage, dose homogeneity, and conformity for this particular case of breast sarcoma.

A straightforward multiparametric quality control protocol for proton magnetic resonance spectroscopy: Validation and comparison of various 1.5 T and 3 T clinical scanner systems.

PURPOSE: The aim of this study was to propose and validate across various clinical scanner systems a straightforward multiparametric quality assurance procedure for proton magnetic resonance spectroscopy (MRS). METHODS: Eighteen clinical 1.5 T and 3 T scanner systems for MRS, from 16 centres and 3 different manufacturers, were enrolled in the study. A standard spherical water phantom was employed by all centres. The acquisition protocol included 3 sets of single (isotropic) voxel (size 20 mm) PRESS acquisitions with unsuppressed water signal and acquisition voxel position at isocenter as well as off-center, repeated 4/5 times within approximately 2 months. Water peak linewidth (LW) and area under the water peak (AP) were estimated. RESULTS: LW values [mean (standard deviation)] were 1.4 (1.0) Hz and 0.8 (0.3) Hz for 3 T and 1.5 T scanners, respectively. The mean (standard deviation) (across all scanners) coefficient of variation of LW and AP for different spatial positions of acquisition voxel were 43% (20%) and 11% (11%), respectively. The mean (standard deviation) phantom T2values were 1145 (50) ms and 1010 (95) ms for 1.5 T and 3 T scanners, respectively. The mean (standard deviation) (across all scanners) coefficients of variation for repeated measurements of LW, AP and T2 were 25% (20%), 10% (14%) and 5% (2%), respectively. CONCLUSIONS: We proposed a straightforward multiparametric and not time consuming quality control protocol for MRS, which can be included in routine and periodic quality assurance procedures. The protocol has been validated and proven to be feasible in a multicentre comparison study of a fairly large number of clinical 1.5 T and 3 T scanner systems.

Dependence of apparent diffusion coefficient measurement on diffusion gradient direction and spatial position - A quality assurance intercomparison study of forty-four scanners for quantitative diffusion-weighted imaging.

PURPOSE: To propose an MRI quality assurance procedure that can be used for routine controls and multi-centre comparison of different MR-scanners for quantitative diffusion-weighted imaging (DWI). MATERIALS AND METHODS: 44 MR-scanners with different field strengths (1 T, 1.5 T and 3 T) were included in the study. DWI acquisitions (b-value range 0-1000 s/mm2), with three different orthogonal diffusion gradient directions, were performed for each MR-scanner. All DWI acquisitions were performed by using a standard spherical plastic doped water phantom. Phantom solution ADC value and its dependence with temperature was measured using a DOSY sequence on a 600 MHz NMR spectrometer. Apparent diffusion coefficient (ADC) along each diffusion gradient direction and mean ADC were estimated, both at magnet isocentre and in six different position 50 mm away from isocentre, along positive and negative AP, RL and HF directions. RESULTS: A good agreement was found between the nominal and measured mean ADC at isocentre: more than 90% of mean ADC measurements were within 5% from the nominal value, and the highest deviation was 11.3%. Away from isocentre, the effect of the diffusion gradient direction on ADC estimation was larger than 5% in 47% of included scanners and a spatial non uniformity larger than 5% was reported in 13% of centres. CONCLUSION: ADC accuracy and spatial uniformity can vary appreciably depending on MR scanner model, sequence implementation (i.e. gradient diffusion direction) and hardware characteristics. The DWI quality assurance protocol proposed in this study can be employed in order to assess the accuracy and spatial uniformity of estimated ADC values, in single- as well as multi-centre studies.

Role of radiotherapy in the treatment of renal cell cancer: updated and critical review.

PURPOSE: The growing incidence of renal cell carcinoma (RCC) raises many questions about the management of these patients. The late clinical presentation, the presence of locally advanced or metastatic disease at diagnosis, the difficulty of radical surgical excision, and radioresistance make it one of the more challenging tumors to treat. The primary objective of this article is to propose an updated and critical review of the role of radiotherapy (RT) in the treatment of RCC. METHODS: This literature review is based on data from meta-analyses and randomized, prospective, and retrospective studies. We collected reports from 1970 to the present about preoperative RT, postoperative RT, stereotactic body RT, radiosurgery, and intraoperative RT in locally advanced renal cancer and in metastatic diseases. RESULTS: We emphasize the progress made in RT technology that allowed the creation of a more personalized and focused treatment with a minimum rate of complications. CONCLUSIONS: In the coming years, new studies will be published to confirm and increase the indications for use of RT.

Diffusion-weighted magnetic resonance imaging in patients with prostate cancer treated with radiotherapy.

AIMS: To evaluate the utility of a multiparametric 3T magnetic resonance imaging (MRI) study using diffusion-weighted images (DWI) for the assessment of prostate cancer before and after radiotherapy (RT). METHODS: A total of 34 patients, who received a histologic diagnosis of prostate adenocarcinoma, underwent MRI examination before and after local RT for the assessment of response to treatment. Apparent diffusion coefficient (ADC) values were calculated and compared. RESULTS: Before RT, DWI shows pathologic restriction of signal, while after RT pathologic restriction of signal was reduced or disappeared. The ADC values were significantly increased after therapy (p<0.05). CONCLUSIONS: The use of DWI with ADC measurements may be an imaging biomarker in the assessment of prostate cancer.

A radiotherapy technique for palliative total scalp irradiation.

A scalp irradiation technique for palliative treatment of a squamous cell carcinoma was discussed. A patient with multiple cutaneous scalp lesions resulting in bleeding and pain was treated with a 3D conformal radiotherapy technique was performed with five 6 MV electron beams without shifting the field borders during the course of the treatment, due to the finality of the treatment (palliative intent). A reduction of planning and delivery complexity has been obtained not considering the junctioning problems. Nevertheless, the 90% of gross tumor volume (GTV) was covered by the 85% of prescription dose with a significant reduction of patient's symptoms (pain and bleeding). Our patient achieved a significant pain response and resolution of bleeding with this technique. Our study revealed that the scalp irradiation by means of electron beam without considering the junction problem is easy and effective for the palliative intent in elderly patients with squamous cell carcinoma.

Comparison between magnetic resonance spectroscopy and diffusion weighted imaging in the evaluation of gliomas response after treatment.

PURPOSE: To compare magnetic resonance spectroscopy (MRS) and diffusion weighted imaging (DWI) in the assessment of progression and regression of brain tumors in order to assess whether there is correlation between MRS and DWI in the monitoring of patients with primary tumors after therapy. METHODS: Magnetic resonance imaging (MRI) has been performed in 80 patients, 48 affected by high grade gliomas (HGG) and 32 affected by low grade gliomas (LGG). The variation of apparent diffusion coefficient (ADC) value and metabolite ratios before and after treatment has been used to test DWI sequences and MRS as predictor to response to therapy. Comparison between post contrast-enhancement sequences, MRS and DWI has been done in terms of accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Moreover statistical correlation of ADC deviations with MRS metabolites variations before and after therapy have been studied. RESULTS: In the case of HGG, MRS shows better sensitivity, specificity, PPV, NPV and accuracy compared to DWI, especially when considering the Choline/N-acetylaspartate (Cho/NAA) ratio. Regarding the LGG, the technique that better evaluates the response to treatment appears to be the DWI. A moderate correlation between ADC deviations and Cho, Lipide (Lip) and Lactate (Lac) has been found in LGG; while NAA revealed to be weakly correlated to ADC variation. Considering HGG, a weak correlation has been found between ADC deviations and MRS metabolites. CONCLUSION: Combination of DWI and MRS can help to characterize different changes related to treatment and to evaluate brain tumor response to treatment.

Critical dose and toxicity index of organs at risk in radiotherapy: analyzing the calculated effects of modified dose fractionation in non-small cell lung cancer.

To increase the efficacy of radiotherapy for non-small cell lung cancer (NSCLC), many schemes of dose fractionation were assessed by a new "toxicity index" (I), which allows one to choose the fractionation schedules that produce less toxic treatments. Thirty-two patients affected by non resectable NSCLC were treated by standard 3-dimensional conformal radiotherapy (3DCRT) with a strategy of limited treated volume. Computed tomography datasets were employed to re plan by simultaneous integrated boost intensity-modulated radiotherapy (IMRT). The dose distributions from plans were used to test various schemes of dose fractionation, in 3DCRT as well as in IMRT, by transforming the dose-volume histogram (DVH) into a biological equivalent DVH (BDVH) and by varying the overall treatment time. The BDVHs were obtained through the toxicity index, which was defined for each of the organs at risk (OAR) by a linear quadratic model keeping an equivalent radiobiological effect on the target volume. The less toxic fractionation consisted in a severe/moderate hyper fractionation for the volume including the primary tumor and lymph nodes, followed by a hypofractionation for the reduced volume of the primary tumor. The 3DCRT and IMRT resulted, respectively, in 4.7% and 4.3% of dose sparing for the spinal cord, without significant changes for the combined-lungs toxicity (p < 0.001). Schedules with reduced overall treatment time (accelerated fractionations) led to a 12.5% dose sparing for the spinal cord (7.5% in IMRT), 8.3% dose sparing for V20 in the combined lungs (5.5% in IMRT), and also significant dose sparing for all the other OARs (p < 0.001). The toxicity index allows to choose fractionation schedules with reduced toxicity for all the OARs and equivalent radiobiological effect for the tumor in 3DCRT, as well as in IMRT, treatments of NSCLC.