MRI quantification of pancreas motion as a function of patient setup for particle therapy -a preliminary study.

Particle therapy (PT) has shown positive therapeutic results in local control of locally advanced pancreatic lesions. PT effectiveness is highly influenced by target localization accuracy both in space, since the pancreas is located in proximity to radiosensitive vital organs, and in time as it is subject to substantial breathing-related motion. The purpose of this preliminary study was to quantify pancreas range of motion under typical PT treatment conditions. Three common immobilization devices (vacuum cushion, thermoplastic mask, and compressor belt) were evaluated on five male patients in prone and supine positions. Retrospective four-dimensional magnetic resonance imaging data were reconstructed for each condition and the pancreas was manually segmented on each of six breathing phases. A k-means algorithm was then applied on the manually segmented map in order to obtain clusters representative of the three pancreas segments: head, body, and tail. Centers of mass (COM) for the pancreas and its segments were computed, as well as their displacements with respect to a reference breathing phase (beginning exhalation). The median three-dimensional COM displacements were in the range of 3 mm. Latero-lateral and superior-inferior directions had a higher range of motion than the anterior-posterior direction. Motion analysis of the pancreas segments showed slightly lower COM displacements for the head cluster compared to the tail cluster, especially in prone position. Statistically significant differences were found within patients among the investigated setups. Hence a patient-specific approach, rather than a general strategy, is suggested to define the optimal treatment setup in the frame of a millimeter positioning accuracy.

Appropriate use of magnetic resonance imaging and ultrasound to detect early silicone gel breast implant rupture in postmastectomy reconstruction.

BACKGROUND: Implant rupture is one of the most important sequelae of breast reconstruction after mastectomy. The primary aim of this study was to compare magnetic resonance imaging and ultrasound evaluation with intraoperative findings and provide a reliable description of the occurrence of each radiological sign. METHODS: The authors prospectively recruited a consecutive series of 102 postmastectomy patients requiring implant change for aesthetic purposes. Magnetic resonance imaging and ultrasound evaluation results were compared with intraoperative findings. Sensitivity, specificity, positive predictive value, negative predictive value, and the overall accuracy of magnetic resonance imaging and ultrasound in detecting ruptured implants were calculated, along with their corresponding 95 percent confidence intervals. RESULTS: Magnetic resonance imaging performs better than ultrasound for diagnosis of breast implant rupture, with overall accuracies of 94 and 72 percent, respectively. The negative predictive value of ultrasound was 85 percent, meaning that in the case of negative ultrasound findings, magnetic resonance imaging may be avoided. Teardrop sign and water droplets are the most common findings on magnetic resonance imaging. CONCLUSIONS: Magnetic resonance imaging should be considered the method of choice for investigating silicone gel implant rupture in postmastectomy patients, and the standardization of magnetic resonance imaging criteria may improve magnetic resonance imaging accuracy. The authors therefore suggest a strategy of screening asymptomatic women with ultrasound every year and with magnetic resonance imaging every 5 years. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, II.

Magnetic resonance mammography in the evaluation of recurrence at the prior lumpectomy site after conservative surgery and radiotherapy.

INTRODUCTION: The aim was to assess the value of magnetic resonance mammography (MRM) in the detection of recurrent breast cancer on the prior lumpectomy site in patients with previous conservative surgery and radiotherapy. METHODS: Between April 1999 and July 2003, 93 consecutive patients with breast cancer treated with conservative surgery and radiotherapy underwent MRM, when a malignant lesion on the site of lumpectomy was suspected by ultrasound and/or mammography. MRM scans were evaluated by morphological and dynamic characteristics. MRM diagnosis was compared with histology or with a 36-month imaging follow-up. Enhancing areas independent of the prior lumpectomy site, incidentally detected during the MRM, were also evaluated. RESULTS: MRM findings were compared with histology in 29 patients and with a 36-month follow-up in 64 patients. MRM showed 90% sensitivity, 91.6% specificity, 56.3% positive predictive value and 98.7% negative predictive value for detection of recurrence on the surgical scar. MRM detected 13 lesions remote from the scar. The overall sensitivity, specificity, positive predictive value and negative predictive value of MRM for detection of breast malignancy were 93.8%, 90%, 62.5% and 98.8%, respectively. CONCLUSION: MRM is a sensitive method to differentiate recurrence from post-treatment changes at the prior lumpectomy site after conservative surgery and radiation therapy. The high negative predictive value of this technique can avoid unnecessary biopsies or surgical treatments.

Survey of computed tomography techniques and absorbed dose in Italian hospitals: a comparison between two methods to estimate the dose-length product and the effective dose and to verify fulfilment of the diagnostic reference levels.

The aim of this study was the production of the first Italian survey of radiation dose in computed tomography (CT) prior to the widespread adoption of multislice CT, in order to have a reference point to facilitate later investigation of dose exposure changes brought by this new CT modality. The collected dose data were compared with diagnostic reference levels (DRLs). The agreement between experimental dose evaluation and Monte Carlo (MC) simulations was investigated. The survey was carried out in 29 Italian hospitals, covered 48 CT scanners and 232 examinations. The dose-length product (DLP) and effective dose (E) values were estimated based on MC simulations for seven clinical protocols using the CT-Dose program. Statistical analysis showed a significant difference (p<0.01) in the DLP between the two methods, with MC values being greater than the experimental ones. For E, the MC values were greater in routine head (8.2%), cervical spine (2.7%) and lumbar spine (2.9%) studies. The weighted CT dose index, the DLP and E were always below the DRLs set by the European Community. This dose survey gives a good but incomplete picture of the Italian CT dose situation and may be useful as a reference baseline for defining clinical multislice protocols in the near future.

Accuracy of computed tomography and magnetic resonance imaging in the detection of lymph node involvement in cervix carcinoma.

UNLABELLED: Lymphnodes status in cervical carcinoma is important in therapeutic planning, and the role of Computed Tomography (CT) and Magnetic Resonance (MR) is controversial: this paper aims to evaluate their accuracy in diagnosing nodal metastases in patients with cervical carcinoma. We reviewed, retrospectively and blindly, CT and MR of 62 patients, before surgical lymphnode resection: 45 of these patients had pre-surgical chemotherapy. Lymphnodes were defined metastatic by CT and MRI when larger than 1 cm short axis. Both diagnoses by the original routine reports and by a second blind expert were compared with pathological reports. RESULTS: combining the reading results of both observers CT showed a sensitivity of 64.6% and specificity of 93.3%; MRI a sensitivity of 72.9% and specificity of 93.1%. Positive Predictive Value was 50.8% for CT and 53% for MR, while Negative Predictive Value was 96% both for CT and MR. The expert Radiologist reviewing the films obtained better results. Inter-observer variability in the lower quadrants was high for each imaging technique (kappa for CT: 0.71; kappa for MRI: 0.84). Both imaging techniques showed similar screening accuracy in identifying nodal metastases. The radiologist's experience is important in determining the performance of the imaging technique. Anyway, CT and MRI are only moderately sensitive for detection of nodal metastases and the clinical impact of their results in patient's management is limited.

MR and CT image fusion for postimplant analysis in permanent prostate seed implants.

PURPOSE: To compare the outcome of two different image-based postimplant dosimetry methods in permanent seed implantation. METHODS AND MATERIALS: Between October 1999 and October 2002, 150 patients with low-risk prostate carcinoma were treated with (125)I and (103)Pd in our institution. A CT-MRI image fusion protocol was used in 21 consecutive patients treated with exclusive brachytherapy. The accuracy and reproducibility of the method was calculated, and then the CT-based dosimetry was compared with the CT-MRI-based dosimetry using the dose-volume histogram (DVH) related parameters recommended by the American Brachytherapy Society and the American Association of Physicists in Medicine. RESULTS: Our method for CT-MRI image fusion was accurate and reproducible (median shift <1 mm). Differences in prostate volume were found, depending on the image modality used. Quality assurance DVH-related parameters strongly depended on the image modality (CT vs. CT-MRI): V(100) = 82% vs. 88%, p < 0.05. D(90) = 96% vs. 115%, p < 0.05. Those results depend on the institutional implant technique and reflect the importance of lowering inter- and intraobserver discrepancies when outlining prostate and organs at risk for postimplant dosimetry. CONCLUSIONS: Computed tomography-MRI fused images allow accurate determination of prostate size, significantly improving the dosimetric evaluation based on DVH analysis. This provides a consistent method to judge a prostate seed implant's quality.

Clinical experience with axillary presentation breast cancer.

We present our experience of 50 cases of occult primary tumours presenting as axillary metastases, all with histological report of adenocarcinoma compatible with mammary carcinoma. After bilateral US and mammography, with MRI and mammoscintigraphy where necessary, ipsilateral breast cancer was suspected in 23 cases and quadrantectomy performed. Breast cancer was found only in 12 (24%). In the other 27 women there was no clinical or instrumental suspicion of breast cancer or other primary disease site, so the main treatment was complete axillary dissection plus radiotherapy to the ipsilateral breast (given to all patients). Chemotherapy alone was given to 27 patients, hormone treatment to 5 patients, and both to 18. Mean follow-up is 41.3 months (range 108-1). Thirty-nine (84%) patients are alive with no evidence of disease, two are alive with breast disease, five patients have died of metastatic disease (with no evidence breast disease). Our experience, like that of the literature, confirms that the breast should be extensively investigated but that blanket investigations are not usually revealing. We present guidelines for the work-up of patients presenting with axillary disease.

Clinical stage I carcinoma of the uterine cervix value of preoperative magnetic resonance imaging in assessing parametrial invasion.

AIMS AND BACKGROUND: The purpose of this prospective study was to assess the efficacy of different MR imaging techniques in the evaluation of parametrial tumor invasion in patients with early stage cervical cancer. METHODS: A total of 73 consecutive patients, clinically considered to have invasive tumor (<3 cm in diameter) confined to the cervix, underwent MR imaging studies at 1 T, according to the following protocol: fast spin-echo (FSE) T2-weighted, gadolinium-enhanced SE T1-weighted, and fat-suppressed gadolinium-enhanced SE T1-weighted sequences. Images obtained with each sequence were evaluated for parametrial invasion with the use of histopathologic findings as the standard of reference. RESULTS: In the assessment of tumor infiltration of the parametrium, with FSE T2-weighted images accuracy was 83%, with SE T1-weighted gadolinium-enhanced images was 65%, and with SE T1-weighted gadolinium-enhanced fat-suppressed images was 72%. The difference between the accuracy rate achieved with FSE T2-weighted images and those obtained with the other two MR sequences was statistically significant (P <0.05). The high negative predictive value (95%) for the exclusion of parametrial tumor invasion was the principal contributor to the staging accuracy obtained with FSE T2-weighted imaging. CONCLUSIONS: Unenhanced FSE T2-weighted imaging is a reliable method for determining the degree of tumor invasion in patients with early stage cervical cancer. Our data suggest that contrast-enhanced sequences, even with the use of the fat suppression technique, have limited value in assessing tumor extension.