Interstitial magnetic resonance lymphography: the clinical effectiveness of a new method.

The aim of this study is to evaluate effectiveness of interstitial magnetic resonance lymphography as an examination for the depiction of the lymphatic system in humans by comparison with direct x-ray lymphography. We studied 14 subjects (two volunteers and 12 patients with clinical suspicion of lymphedema of the lower extremities). We first administered subcutaneous gadobutrol between the toes and performed MR lymphography. After seven days, we injected lipiodol into the lymph vessels of 8 patients and performed x-ray direct lymphography to compare findings of two methods. We identified the normal lymphatic system (lymph vessels and inguinal lymph nodes) of volunteers. In seven subjects, we were able to image an abnormal lymphatic system with decreased number of lymph vessels, lymphoceles, and ectatic lymph vessels. In three subjects we identified both an abnormal lymphatic and venous system and in two patients only the venous system. In all cases x-ray direct lymphography confirmed the findings of the MR lymphography. No side effects were observed from either contrast agent. We expect that in the future, interstitial MR lymphography will be improved and evolve into a valuable diagnostic tool for the evaluation of lymphatic diseases particularly those who present with primarily lymphedema in the lower limbs or second, in regions other than extremities.

Leiomyosarcoma of the inferior vena cava--an unusual case.

Primary tumors arising from great vessels like the aorta, pulmonary artery or inferior vena cava (IVC) are rare. The latter is the commonest site of its occurrence. It arises from the smooth muscle cells of the vessel wall. Aggressive surgical management should be attempted to excise it whenever possible. We describe a case of primary inferior vena cava tumor involving all three segments of the abdominal inferior vena cava infrarenal, suprarenal and retrohepatic vena cava, along with right kidney, right adrenal as well as right hepatic vein and left renal vein. We resected it completely without reconstruction of the IVC. The patient is doing well seven months after surgery without having any renal insufficiency, hepatic insufficiency or leg edema and having optimum quality of life. To our knowledge, this is the first case of such a long segment IVC leiomyosarcoma treated without IVC reconstruction, and despite its extent and concomitant involvement of the right kidney, right adrenal, right hepatic vein and left renal vein, it had a favorable response combining prolongation of survival and satisfactory quality of life.

Interstitial magnetic resonance lymphography: is it a new method for the diagnosis of lymphedema?

AIM: The aim of this study was to evaluate the method of interstitial magnetic resonance lymphography (MRL) as an examination for the depiction of the lymphatic system in humans in comparison with the method of direct X-ray lymphography. METHODS: We studied 6 persons, 2 volunteers and 4 patients with clinical suspicion of lymphedema in lower extremities. We administered subcutaneous gadobutrol for the MRL with a volume of 5 mL composed of 4.5 mL of Gadobutrol mixed with 0.5 mL of lidocaine hydrochloride and after 7 days lipiodol in the lymph vessel for the X-ray direct lymphography (in 3 patients) in order to compare the findings of the two METHODS: We then followed up all individuals for 7 days for any possible side effect of the contrast agents. RESULTS: Using MRL, we depicted the lymphatic system (lymph vessels and inguinal lymph nodes) of volunteers in 60 min. Moreover, in patients we depicted several abnormalities of the lymphatic system including decreased number of lymph vessels, lymphocele and ectatic lymph vessels. X-ray direct lymphography confirmed the findings of the MRL in all cases. No side effects were observed. CONCLUSION: In our pilot study, Gadobutrol seems to be a good contrast agent for the painless depiction of the lymphatic system in humans through interstitial MRL. More extensive studies are needed in order to establish the efficacy and the dosage of Gadobutrol.

Radiobiological modelling of dose-gradient effects in low dose rate, high dose rate and pulsed brachytherapy.

This paper presents a generalization of a previously published methodology which quantified the radiobiological consequences of dose-gradient effects in brachytherapy applications. The methodology uses the linear-quadratic (LQ) formulation to identify an equivalent biologically effective dose (BED(eq)) which, if applied uniformly to a specified tissue volume, would produce the same net cell survival as that achieved by a given non-uniform brachytherapy application. Multiplying factors (MFs), which enable the equivalent BED for an enclosed volume to be estimated from the BED calculated at the dose reference surface, have been calculated and tabulated for both spherical and cylindrical geometries. The main types of brachytherapy (high dose rate (HDR), low dose rate (LDR) and pulsed (PB)) have been examined for a range of radiobiological parameters/dimensions. Equivalent BEDs are consistently higher than the BEDs calculated at the reference surface by an amount which depends on the treatment prescription (magnitude of the prescribed dose) at the reference point. MFs are closely related to the numerical BED values, irrespective of how the original BED was attained (e.g., via HDR, LDR or PB). Thus, an average MF can be used for a given prescribed BED as it will be largely independent of the assumed radiobiological parameters (radiosensitivity and alpha/beta) and standardized look-up tables may be applicable to all types of brachytherapy treatment. This analysis opens the way to more systematic approaches for correlating physical and biological effects in several types of brachytherapy and for the improved quantitative assessment and ranking of clinical treatments which involve a brachytherapy component.

Technique charts for Kodak EC-L film screen system for portal localization in a 6MV X-ray beam.

Port films are used in radiotherapy for visual evaluation of the radiation fields and subsequent quantitative analysis. Common port films suffer from poor image quality compared to the simulator-diagnostic films and is desirable to determine the appropriate exposure required for the best image contrast. The aim of this work is to generate technique charts for the Kodak EC-L film screen system for use in a 6MV x-ray beam. Three homogeneous water phantoms were used to simulate head-neck, thorax and abdomen dimensions of adult human, correspondingly. The film screen system was calibrated in a 6MV x-ray beam and under various irradiation conditions. The film screen system behavior was studied as a function of phantom thickness, field size and air gap between the phantom and the film screen system. In each case the optimum film exposure which produces the maximum image contrast was determined. The generated technique charts for the EC-L film screen system and for a 6 MV x-ray beam are used in our radiotherapy department for daily quality assurance of the radiotherapy procedure.

Dose verification of single shot gamma knife applications using VIPAR polymer gel and MRI.

This work describes an experimental procedure with potential to assess the overall accuracy associated with gamma knife clinical applications, from patient imaging and dosimetry planning to patient positioning and dose delivery using the automated positioning system of a Leksell Gamma Knife model C. The VIPAR polymer gel-MRI dosimetry method is employed due to its inherent three-dimensional feature and linear dose response over the range of gamma knife applications. Different polymer gel vials were irradiated with single shot gamma knife treatment plans using each of the four available collimator helmets to deliver a maximum dose of 30 Gy. Percentage relative dose results are presented not only in the form of one-dimensional profiles but also planar isocontours and isosurfaces in three dimensions. Experimental results are compared with corresponding Gammaplan treatment planning system calculations as well as acceptance test radiochromic film measurements. A good agreement, within the experimental uncertainty, is observed between measured and expected dose distributions. This experimental uncertainty is of the order of one imaging pixel in the MRI gel readout session (<1 mm) and allows for the verification of single shot gamma knife applications in terms of acceptance specifications for precision in beam alignment and accuracy. Averaging net R(2) results in the dose plateau of the 4 mm and 18 mm collimator irradiated gel vials, which were MR scanned in the same session, provides a crude estimate of the 4 mm output factor which agrees within errors with the default value of 0.870.

A Monte Carlo investigation of the dosimetric characteristics of the VariSource 192Ir high dose rate brachytherapy source.

An analytical Monte Carlo simulation code, incorporating in detail source construction and dimensions, was used to investigate the dosimetric characteristics of the VariSource 192Ir high dose rate brachytherapy source. Dose-rate constant, radial dose functions, and anisotropy functions, utilized in the AAPM Task Group 43 dose estimation formalism, were calculated with the source centered in a spherical water phantom of 30 cm in diameter. The results, which are in agreement with the corresponding data available in the literature, are compared to those obtained in our previous study for the widely used microSelectron 192Ir high dose-rate brachytherapy source. The dose-rate constant was found to be equal to 1.043 +/- 0.005 cGy h(-1) U(-1) for the VariSource, compared to a value of 1.116 +/- 0.006 cGy h(-1) U(-1) calculated for the microSelectron. Significant differences in the anisotropy of the two sources are observed only for polar angles close to their long axis and are due to their different dimensions.

Monte Carlo and TLD dosimetry of an 192Ir high dose-rate brachytherapy source.

An analytical Monte Carlo simulation code has been used to perform dosimetry calculations around an 192Ir high dose-rate brachytherapy source utilized in the widely used microSelectron afterloaded system. Radial dose functions, dose rate constant and anisotropy functions, utilized in the AAPM Task Group 43 dose estimation formalism, have been calculated. In addition, measurements of anisotropy functions using LiF TLD-100 rods have been performed in a polystyrene phantom to support our Monte Carlo calculations. The energy dependence of LiF TLD response was investigated over the whole range of measurement distances and angles. TLD measurements and Monte Carlo calculations are in agreement to each other and agree with published data. The influence of phantom dimensions on calculations was also investigated. Radial dose functions were found to depend significantly on phantom dimensions at radial distances near phantom edges. Deviations of up to 25% are observed at these distances due to the lack of full scattering conditions, indicating that body dimensions should be taken into account in treatment planning when the absorbed dose is calculated near body edges. On the other hand, anisotropy functions do not demonstrate a strong dependence on phantom dimensions. However, these functions depend on radial distance at angles close to the longitudinal axis of the source, where deviations of up to 20% are observed.

Dosimetry of 192Ir wires for LDR interstitial brachytherapy following the AAPM TG-43 dosimetric formalism.

Implementation of the AAPM Task Group 43 dosimetric formalism for 192Ir wires used as interstitial sources in low dose-rate (LDR) brachytherapy applications is investigated. Geometry factors, dose-rate constant values, radial dose functions, and anisotropy functions, utilized in this formalism, were calculated for various lengths of all commercially available wire source designs by means of a well-established Monte Carlo simulation code and an improved modification of the Sievert integral method. Results are presented in the form of look up tables that allow interpolation for dose-rate calculations around all practically used wire lengths, with accuracy acceptable for clinical applications.

Dosimetry comparison of 192Ir sources.

192Ir sources besides being widely utilized in the field of conventional brachytherapy also find use in contemporary peripheral and coronal intravascular applications. In this study, the same Monte Carlo simulation code and input data were used to investigate differences between the dose rate distributions of the most commonly used 192Ir sources in the cm and mm distance range. Findings are discussed in view of differences in source and encapsulation dimensions as well as structural details. Results are presented in the AAPM TG-43 formalism, as generalized by AAPM TG-60, for five 192Ir HDR source designs as well as an LDR seed and an LDR wire source. Dose rate constants of the sources at r0 = 1 cm and r0 = 2 mm were found proportional to the corresponding geometry factors along the transverse source bisectors and an equation of the form lambda r0(cGyh(-1) U(-1)) = 1.12 x G(r0,90 degrees) provides results within clinical accuracy (less than 2%) for any 192Ir source. Radial dose functions do not depend significantly on source and encapsulation geometry and agree within 2% with that of a point 192Ir source. Anisotropy is of importance for accurate dosimetry at the cm distance range but it does not affect dose rate in the mm distance range significantly. At such short radial distances the source geometry factor defines the shape of isodose lines. Dose uniformity at given distances from the sources is strongly dependent on source dimensions as indicated by dose rate profiles in polar and Cartesian coordinates.

Polymer gel dosimetry using a three-dimensional MRI acquisition technique.

In this work, three-dimensional (3-D) MRI techniques are employed in N-Vinylpyrrolidone-Argon-(VIPAR-) based polymer gel dosimetry. VIPAR gels were irradiated using a Nucletron microSelection 192Ir HDR brachytherapy remote afterloading system with single source dwell position and intravascular brachytherapy irradiation protocols. A single VIPAR gel and a single irradiation are adequate to obtain the full calibration curve needed. The 3-D dose distributions obtained with the 3-D MRI method were found to be in good agreement with the corresponding Monte Carlo calculations, for brachytherapy and intravascular irradiations. The method allows the reconstruction of isodose contours over any plane, with increased spatial resolution and accuracy following a single MR acquisition. VIPAR gel measurements using a 3-D MRI readout technique can be of particular use in the experimental dosimetry of brachytherapy sources, as well as for dose verification purposes when complex irradiation regimes and three-dimensional dose gradients are investigated.

Abdominal aortic aneurysm and renal artery stenosis: renal function and blood pressure before and after endovascular treatment.

We describe three patients with abdominal aortic aneurysm (AAA) and renal artery stenosis (RAS). These patients were treated by placement of an aortic endograft and angioplasty or stenting of the renal artery. After the procedure renal function improved or remained stable in two patients and deteriorated slightly in one. Blood pressure was reduced in one hypertensive patient and remained normal in the other two normotensive patients. In conclusion, simultaneous treatment of AAA and RAS with aortic endograft placement and renal artery angioplasty with or without stent, is a safe and effective technique for selected high-risk patients.

Transplant renal artery stenosis: hypertension and graft function before and after angioplasty.

We present a case, who after 15 years of renal transplantation developed severe deterioration of her hypertension without alteration in renal function. Colour Doppler sonography revealed a 90% stenosis near the anastomosis of the graft artery to iliac artery, which was successfully and uneventfully corrected by percutaneous balloon angioplasty. Following the procedure the blood pressure control dramatically improved and her antihypertensive regimen returned and remained at baseline for the subsequent year of observation. Renal function remained normal and stable before and after angioplasty.

Comparison of tropisetron and chlorpromazine combinations in the control of nausea and vomiting of patients with advanced cancer.

The single-institution, prospective, randomized trial was performed to evaluate the efficacy of tropisetron and chlorpromazine in the management of nausea and vomiting of terminal cancer patients. Patients had no recent chemotherapy or radiotherapy, and emesis was not due to bowel obstruction, electrolytic or metabolic disturbances, drug intake, or intracranial disease. One hundred and sixty patients randomly received either (a) chlorpromazine (CLO) (50 mg/day) plus dexamethasone (DEX) (2 mg/day), (b) chlorpromazine (25 mg/day) plus tropisetron (TRO) (5 mg/day), (c) chlorpromazine (25 mg/day plus tropisetron (5 mg/day) plus dexamethasone (2 mg/day), or (d) tropisetron (TRO) (5 mg/day). Patients were monitored from day 1 to day 15. No nausea or vomiting was defined as "total" control. On day 15, total vomiting control was achieved in 33.3% of the patients receiving CLO + DEX, 84.6% of the patients receiving CLO + TRO, 92.5% of the patients receiving CLO + TRO + DEX, and 78.9% of the patients receiving TRO. Total control of nausea was achieved in 18.0% of the patients receiving CLO + DEX, 74.4% of the patients receiving (CLO + TRO), 85.0% of the patients receiving CLO + TRO + DEX, and 65.8% of the patients receiving TRO. Tropisetron-containing combinations produced significant control of nausea and vomiting from the third day onward. All antiemetic drugs were well tolerated. These data suggest that tropisetron-containing combinations or tropisetron as a single agent are much more effective in the control of emesis in patients with advanced cancer than the conventional antiemetic combination of chlorpromazine plus dexamethasone. Tropisetron is well tolerated and may be the best choice for controlling persistent nausea and vomiting in terminal cancer patients.

Evaluation of the performance of VIPAR polymer gels using a variety of x-ray and electron beams.

The aim of this investigation was the evaluation of the usefulness of N-vinyl pyrrolidone argon (VIPAR) polymer gel dosimetry for relative dose measurements using the majority of types and energies of radiation beams used in clinical practice. For this reason, VIPAR polymer gels were irradiated with the following beams: 6 and 23 MV photons (maximum dose: 15 Gy) and 6, 9, 12, 15, 18 and 21 MeV electrons (90% dose: 15 Gy). Using 6 MV x-rays, a linear gel dose response was verified for doses up to 20 Gy. Assuming linearity of response for the rest of the photon and electron beams used in this study, percentage depth dose measurements were derived. For all beams used and the range of relative doses studied, a satisfying agreement was observed between percentage depth dose measurements performed using the VIPAR gel-MRI method and an ion chamber, validating the assumption that a linear gel dose response holds for all photon and electron beams studied. VIPAR gels, therefore, can be used for relative dose distribution measurements using photons or electrons of any typical energy used in external radiotherapy applications. It is also demonstrated that two-dimensional dose distribution measurements through an irradiated (9 MeV electrons, 3 cm x 3 cm cone) VIPAR gel volume can be easily obtained.

A new polymer gel for magnetic resonance imaging (MRI) radiation dosimetry.

New composition polymer gels, the N-vinylpyrrolidone argon (VIPAR) gels, were developed and investigated as MRI dosimeters. VIPAR gels were irradiated in the dose range of 0-12 Gy by a 6 MV x-ray linear accelerator and MR-scanned in a 1.5 T magnetic resonance imager. A linear relationship was found between absorbed dose and spin spin relaxation rate R2. The dose sensitivity was found to be approximately 0.1 s(-1) Gy(-1) for a gel composition of 4% w/w in N-vinylpyrrolidone, 4% w/w in N,N'-methylene-bisacrylamide, 5% w/w in gelatine type A and 87% w/w in water. This dose sensitivity was stable with time and did not deteriorate even when a boost radiation dose of 2.5 Gy was applied 15 days after the first irradiation. Good reproducibility of these results was observed when a new batch of gels was produced and used for corresponding measurements and analysis.

Dose rate calculations around 192Ir brachytherapy sources using a Sievert integration model.

The classical Sievert integral method is a valuable tool for dose rate calculations around brachytherapy sources, combining simplicity with reasonable computational times. However, its accuracy in predicting dose rate anisotropy around 192Ir brachytherapy sources has been repeatedly put into question. In this work, we used a primary and scatter separation technique to improve an existing modification of the Sievert integral (Williamson's isotropic scatter model) that determines dose rate anisotropy around commercially available 192Ir brachytherapy sources. The proposed Sievert formalism provides increased accuracy while maintaining the simplicity and computational time efficiency of the Sievert integral method. To describe transmission within the materials encountered, the formalism makes use of narrow beam attenuation coefficients which can be directly and easily calculated from the initially emitted 192Ir spectrum. The other numerical parameters required for its implementation, once calculated with the aid of our home-made Monte Carlo simulation code, can be used for any 192Ir source design. Calculations of dose rate and anisotropy functions with the proposed Sievert expression, around commonly used 192Ir high dose rate sources and other 192Ir elongated source designs, are in good agreement with corresponding accurate Monte Carlo results which have been reported by our group and other authors.

Narrow stereotactic beam profile measurements using N-vinylpyrrolidone based polymer gels and magnetic resonance imaging.

In this work, polymer gel-MRI dosimetry (using VIPAR gels), radiographic film and a PinPoint ion chamber were used for profile measurements of 6 MV x-ray stereotactic beams of 5 and 10 mm diameter. The VIPAR gel-MRI method exhibited a linear dose response up to 32 Gy. VIPAR gels were found to resolve the penumbra region quite accurately, provided that the in-plane image resolution of the related T2-map is adequate (< or = 0.53 mm). T2-map slice thickness had no significant effect on beam profile data. VIPAR measurements performed with a spatial resolution of 0.13 mm provided penumbra widths (80%-20% distance) of 1.34 and 1.70 mm for the 5 and 10 mm cones respectively. These widths were found to be significantly smaller than those obtained with the film (2.23 mm for the 5 mm cone, 2.45 mm for the 10 mm cone) and PinPoint (2.25 mm for the 5 mm cone, 2.52 mm for the 10 mm cone) methods. Regarding relative depth dose measurements, good correlation between VIPAR gel and PinPoint data was observed. In conclusion, polymer gel-MRI dosimetry can provide relatively accurate profile data for very small beams used in stereotactic radiosurgery since it can overcome, to some extent, the problems related to the finite size of conventional detectors.

The effect of various regimens of hormone replacement therapy on mammographic breast density.

OBJECTIVES: To evaluate the effect of three distinct hormone replacement therapy regimens on mammography. METHODS: 121 postmenopausal women who had never received or were past users of hormone replacement therapy were studied prospectively. Women with an intact uterus were randomly allocated either to conjugated equine estrogens 0.625 mg plus medroxyprogesterone acetate 5 mg (CEE/MPA, n=34) or to 17beta-estradiol 2 mg plus norethisterone acetate 1 mg (E(2)/NETA, n=35). Hysterectomized women received CEE 0.625 mg (CEE, n=25). Women who either declined or did not qualify for treatment served as controls (n=27). Treatment was continuous and the study period lasted 12 months. Main outcome measures were the changes according to Wolfe classification between baseline and 12-month-mammograms. RESULTS: No increase in breast density was identified in any of the women in the control group. Two women (8%) in the CEE group showed an increase in breast density. Four women (11.8%) in the CEE/MPA and 11 women (31.4%) in the E(2)/NETA group revealed an increase in breast density. No woman in the therapy groups showed an involution of fibroglandular tissue while seven women (25.9%) in the control group exhibited involution of breast parenchyma. CONCLUSIONS: Our study suggests that hormone replacement therapy may suspend breast involution but does not increase breast density in the majority of patients. In the minority of patients who show a density increase, the magnitude of this increase varies according to the regimen employed.

Stent therapy for malignant superior vena cava syndrome: should be first line therapy or simple adjunct to radiotherapy.

UNLABELLED: The goal of this paper is to present our experience with superior vena cava (SVC) stenting, as first line procedure for immediate relief, in patients with malignancy, and its potential influence in the subsequent radiotherapy (XRT). Over a 1-year period, 18 patients with SVC syndrome due to severe stenosis secondary to mediastinal malignancy were referred for stent insertion. A SVC score was used to measure treatment effectiveness. Stent insertion had been successful in 18/18 patients (technical success 100%). All patients experienced symptomatic relief within few hours of the procedure. There were no major complications. In all patients we were able to start radiotherapy (XRT) the next day, after stenting according to our new institutional protocol. All patients were able to comply with the XRT program, perfectly well. CONCLUSIONS: SVC stenting provides immediate significant relief of the very annoying SVC syndrome symptoms, thus facilitating excellent compliance of all the patients to the subsequently XRT protocols. We strongly recommend SVC stenting as first line procedure, in patients with SVC syndrome due to malignancy prior to radiotherapy.