Parametrized rectal dose and associations with late toxicity in prostate cancer radiotherapy

Objective:

We investigated possible associations between planned dose–volume parameters and rectal late toxicity in 170 patients having radical prostate cancer radiotherapy.

Methods:

For each patient, the rectum was outlined from anorectal junction to sigmoid colon, and rectal dose was parametrized using dose–volume (DVH), dose–surface (DSH) and dose–line (DLH) histograms. Generation of DLHs differed from previous studies in that the rectal dose was parametrized without first unwrapping onto 2-dimensional dose–surface maps. Patient-reported outcomes were collected using a validated Later Effects in Normal Tissues Subjective, Objective, Management and Analytic questionnaire. Associations between dose and toxicity were assessed using a one-sided Mann–Whitney U test.

Results:

Associations (p < 0.05) were found between equieffective dose (EQD2₃) and late toxicity as follows: overall toxicity with DVH and DSH at 13–24 Gy; proctitis with DVH and DSH at 25–36 Gy and with DVH, DSH and DLH at 61–67 Gy; bowel urgency with DVH and DSH at 10–20 Gy. None of these associations met statistical significance following the application of a Bonferroni correction.

Conclusion:

Independently confirmed associations between rectal dose and late toxicity remain elusive. Future work to increase the accuracy of the knowledge of the rectal dose, either by accounting for interfraction and intrafraction rectal motion or via stabilization of the rectum during treatment, may be necessary to allow for improved dose–toxicity comparisons.

Advances in knowledge:

This study is the first to use parametrized DLHs to study associations with patient-reported toxicity for prostate radiotherapy showing that it is feasible to model rectal dose mapping in three dimensions.     

Can treatment of pediatric Hodgkin’s lymphoma be improved by PET imaging and proton therapy?

Background and purpose

To explore a new positron emission tomography (PET)-based target concept for pediatric Hodgkin’s lymphoma (PHL).

Patients and methods

For 10 patients, the planning target volume PTV1 was based on initial CT tumor extension and PTV2 on anatomy-related PET-positive lymph node levels after chemotherapy. The treatment techniques investigated (prescribed dose 19.8 Gy) comprised opposed-field (2F), intensity-modulated photon (IMXT), and single-field (PS) proton techniques. Treatment concepts were compared concerning dose-volume histogram (DVH) parameters and organ-equivalent doses (OED).

Results

The median PTV1 and PTV2 were 902?±?555 cm³ and 281?±?228 cm³. When using PTV2 instead of PTV1 for all techniques, the D_2% of the heart was reduced from 14 to 9 Gy and the D_mean of the thyroid from 16.6 to 2.7 Gy. Low- (20%), median- (50%), and high-dose volumes (80%) were reduced by 60% for the heart and bones using PTV2. PS reduced the high-dose volume of the lungs and the heart by up to 60%. IMXT increased the low-dose volumes and OED. PTV2 reduced OED by 54?±?10% for all organs at risk.

Conclusion

PTV2 has a high impact on the treated volume and on sparing of organs at risk. The combination of an adaptive target volume definition with protons could contribute to future PHL treatment concepts.     

Protocol-based image-guided salvage brachytherapy

Purpose

To assess the overall clinical outcome of protocol-based image-guided salvage pulsed-dose-rate brachytherapy for locally recurrent prostate cancer after radiotherapy failure particularly regarding feasibility and side effects.

Patients and methods

Eighteen consecutive patients with locally recurrent prostate cancer (median age, 69 years) were treated during 2005–2011 with interstitial PDR brachytherapy (PDR-BT) as salvage brachytherapy after radiotherapy failure. The treatment schedule was PDR-BT two times with 30 Gy (pulse dose 0.6 Gy/h, 24 h per day) corresponding to a total dose of 60 Gy. Dose volume adaptation was performed with the aim of optimal coverage of the whole prostate (V₁₀₀ >?95?%) simultaneously respecting the protocol-based dose volume constraints for the urethra (D_0.1 cc <?130?%) and the rectum (D_2 cc <?50–60?%) taking into account the previous radiation therapy. Local relapse after radiotherapy (external beam irradiation, brachytherapy with J-125 seeds or combination) was confirmed mostly via choline-PET and increased PSA levels. The primary endpoint was treatment-related late toxicities—particularly proctitis, anal incontinence, cystitis, urinary incontinence, urinary frequency/urgency, and urinary retention according to the Common Toxicity Criteria. The secondary endpoint was PSA-recurrence-free survival.

Results

We registered urinary toxicities only. Grade 2 and grade 3 toxicities were observed in up to 11.1?% (2/18) and 16.7?% (3/18) of patients, respectively. The most frequent late-event grade 3 toxicity was urinary retention in 17?% (3/18) of patients. No late gastrointestinal side effects occurred. The biochemical PSA-recurrence-free survival probability at 3 years was 57.1?%. The overall survival at 3 years was 88.9?%; 22?% (4/18) of patients developed metastases. The median follow-up time for all patients after salvage BT was 21 months (range, 8–77 months).

Conclusion

Salvage PDR-brachytherapy of the prostate following local failure after radiation therapy is a treatment option with a low rate of genitourinary side effects and no late gastrointestinal side effects. The treatment efficacy in the first 3 years is promising.     

Treatment planning after hydrogel injection during radiotherapy of prostate cancer

Purpose

Imaging for treatment planning shortly after hydrogel injection is optimal for practical purposes, reducing the number of appointments. The aim was to evaluate the actual difference between early and late imaging.

Patients and methods

Treatment planning computed tomography (CT) was performed shortly after injection of 10 ml hydrogel (CT1) and 1–2 weeks later (CT2) for 3 patients. The hydrogel was injected via the transperineal approach after dissecting the space between the prostate and rectum with a saline/lidocaine solution of at least 20-ml. Hydrogel volume and distances between the prostate and rectal wall were compared. Intensity-modulated radiotherapy (IMRT) plans up to a dose of 78 Gy were generated (rectum V₇₀?<?20?%, rectum V₅₀?<?50?%; with the rectum including hydrogel volume for planning).

Results

A mean planning treatment volume of 104 cm³ resulted for a prostate volume of 37 cm³. Hydrogel volumes of 30 and 10 cm³ were determined in CT1 and CT2, respectively. Distances between the prostate and rectal wall at the levels of the base, middle, and apex were 1.7 cm, 1.6 cm, 1.5 cm in CT1 and 1.3 cm, 1.2 cm, 0.8 cm in CT2, respectively, corresponding to a mean decrease of 24, 25, and 47?%. A small overlap between the PTV and the rectum was found only in 1 patient in CT2 (0.2 cm³). The resulting mean rectum (without hydrogel) V₇₅, V₇₀, V₆₀, V₅₀ increased from 0?%, 0?%, 0.6?%, 10?% in CT1 to 0.1?%, 1.2?%, 6?%, 20?% in CT2, respectively.

Conclusion

Treatment planning based on imaging shortly after hydrogel injection overestimates the actual hydrogel volume during the treatment as a result of not-yet-absorbed saline solution and air bubbles.     

Dose-escalated simultaneous integrated-boost treatment of prostate cancer patients via helical tomotherapy

Purpose

The goal of this work was to assess the feasibility of moderately hypofractionated simultaneous integrated-boost intensity-modulated radiotherapy (SIB-IMRT) with helical tomotherapy in patients with localized prostate cancer regarding acute side effects and dose–volume histogram data (DVH data).

Methods

Acute side effects and DVH data were evaluated of the first 40 intermediate risk prostate cancer patients treated with a definitive daily image-guided SIB-IMRT protocol via helical tomotherapy in our department. The planning target volume including the prostate and the base of the seminal vesicles with safety margins was treated with 70?Gy in 35 fractions. The boost volume containing the prostate and 3?mm safety margins (5?mm craniocaudal) was treated as SIB to a total dose of 76?Gy (2.17?Gy per fraction). Planning constraints for the anterior rectal wall were set in order not to exceed the dose of 76?Gy prescribed to the boost volume. Acute toxicity was evaluated prospectively using a modified CTCAE (Common Terminology Criteria for Adverse Events) score.

Results

SIB-IMRT allowed good rectal sparing, although the full boost dose was permitted to the anterior rectal wall. Median rectum dose was 38?Gy in all patients and the median volumes receiving at least 65?Gy (V65), 70?Gy (V70), and 75?Gy (V75) were 13.5%, 9%, and 3%, respectively. No grade?4 toxicity was observed. Acute grade?3 toxicity was observed in 20% of patients involving nocturia only. Grade?2 acute intestinal and urological side effects occurred in 25% and 57.5%, respectively. No correlation was found between acute toxicity and the DVH data.

Conclusion

This institutional SIB-IMRT protocol using daily image guidance as a precondition for smaller safety margins allows dose escalation to the prostate without increasing acute toxicity.     

External-beam radiotherapy and/or HDR brachytherapy in postoperative endometrial cancer patients: clinical outcomes and toxicity rates

Purpose

The objectives of this study were to evaluate local disease control, overall survival (OS), disease-free survival (DFS) and local relapse-free survival (LRFS) in patients with endometrial cancer undergoing adjuvant vaginal brachytherapy (VBT)±external-beam radiotherapy (EBRT).

Materials and methods

From September 2007 to February 2011, 40 patients with endometrial cancer were retrospectively analysed. Surgery consisted of total hysterectomy and bilateral salpingo-oophorectomy without node dissection (16 patients) or with bilateral pelvic node dissection (24 patients). The stage distribution was as follows: two IA, nine IB, 12 IC, five IIA, eight IIB, two IIIA and two IIIC. Thirty-four patients underwent EBRT and VBT. Six patients received VBT alone.

Results

Median follow-up was 26 months. The 5-year OS and DFS were 96.4% and 86.9%, respectively. No local recurrence was observed. Four patients presented distant disease (three had lung metastases and one had hepatic node metastases). Acute EBRT-related toxicities were seen in 15 (38%) patients. We recorded late toxicities in 14 patients (35%). There was no evidence of grade 3–4 toxicity.

Conclusions

Adjuvant EBRT and/or VBT in patients with endometrial cancer showed good outcomes in terms of local disease control, with an acceptable toxicity profile.     

Pelvic Ewing sarcomas

Purpose

The goal of the present work was to assess the potential advantage of intensity-modulated radiotherapy (IMRT) over three-dimensional conformal radiotherapy (3D-CRT) planning in pelvic Ewing’s sarcoma.

Patients and methods

A total of 8 patients with Ewing sarcoma of the pelvis undergoing radiotherapy were analyzed. Plans for 3D-CRT and IMRT were calculated for each patient. Dose coverage of the planning target volume (PTV), conformity and homogeneity indices, as well as further parameters were evaluated.

Results

The average dose coverage values for PTV were comparable in 3D-CRT and IMRT plans. Both techniques had a PTV coverage of V₉₅ >?98?% in all patients. Whereas the IMRT plans achieved a higher conformity index compared to the 3D-CRT plans (conformity index 0.79?±?0.12 vs. 0.54?±?0.19, p?=?0.012), the dose distribution across the target volumes was less homogeneous with IMRT planning than with 3D-CRT planning. This difference was statistically significant (homogeneity index 0.11?±?0.03 vs. 0.07?±?0.0, p?=?0.035). For the bowel, D_mean and D_1%, as well as V₂ to V₆₀ were reduced in IMRT plans. For the bladder and the rectum, there was no significant difference in D_mean. However, the percentages of volumes receiving at least doses of 30, 40, 45, and 50 Gy (V₃₀ to V₅₀) were lower for the rectum in IMRT plans. The volume of normal tissue receiving at least 2 Gy (V₂) was significantly higher in IMRT plans compared with 3D-CRT, whereas at high dose levels (V₃₀) it was significantly lower.

Conclusion

Compared to 3D-CRT, IMRT showed significantly better results regarding dose conformity (p?=?0.012) and bowel sparing at dose levels above 30 Gy (p?=?0.012). Thus, dose escalation in the radiotherapy of pelvic Ewing’s sarcoma can be more easily achieved using IMRT.     

Interstitial hyperthermia of the prostate in combination with brachytherapy

Objective

A retrospective study to evaluate the feasibility and toxicity of interstitial hyperthermia (IHT) combined with high-dose-rate (HDR) brachytherapy as the initial treatment for low- and intermediate-risk prostate cancer, and as a salvage therapy in previously irradiated patients with local recurrence.

Patients and methods

Between 18 December 2008 and 5 September 2012, 73  prostate cancer patients were treated with interstitial HDR brachytherapy of the prostate combined with IHT. In 54 patients this was the initial therapy for prostate cancer, while the other 19 were treated for local recurrence after previously undergoing external beam radiotherapy (EBRT). Toxicity for the organs of the genitourinary system and rectum was assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v. 4.03 within 3 months after treatment.

Results

Median follow-up was 15 months (range 3–46). The combination of HDR brachytherapy and IHT was well tolerated. The toxicity profile was similar to that of HDR brachytherapy when not combined with hyperthermia. The most common minor complications were urinary frequency (grade 1: 37?%; grade 2: 22?%), nocturia (three times per night: 29?%; four- or more times per night: 20?%) and transient weakening of the urine stream (grade 1: 36?%; grade 2: 11?%). No early rectal complications were observed in the patient group and the severity of genitourinary toxicity was only grade 1–2.

Conclusion

Early tolerance of IHT in combination with HDR brachytherapy is good. Further prospective clinical studies should focus on the effects of combining IHT with HDR brachytherapy and the influence of this adjuvant therapy on biochemical disease-free survival, local control and overall survival.     

Time course of late rectal- and urinary bladder side effects after MRI-guided adaptive brachytherapy for cervical cancer

Background and purpose

To analyze the time course of late rectal- and urinary bladder complications after brachytherapy for cervical cancer and to compare the incidence- and prevalence rates thereof.

Patients and methods

A total of 225 patients were treated with external-beam radiotherapy (EBRT) and magnetic resonance imaging (MRI)-guided brachytherapy with or without chemotherapy. Late side effects were assessed prospectively using the Late Effects in Normal Tissue—Subjective, Objective, Management and Analytic (LENT/SOMA) scale. The parameters analyzed were time to onset, duration, actuarial incidence- (occurrence of new side effects during a defined time period) and prevalence rates (side effects existing at a defined time point).

Results

Median follow-up was 44 months. Side effects (grade 1–4) in rectum and bladder were present in 31 and 49 patients, 14 and 27 months (mean time to onset) after treatment, respectively. All rectal and 76?% of bladder side effects occurred within 3 years after radiotherapy. Mean duration of rectal events was 19 months; 81?% resolved within 3 years of their initial diagnosis. Mean duration of bladder side effects was 20 months; 61?% resolved within 3 years. The 3- and 5-year actuarial complication rates were 16 and 19?% in rectum and 18 and 28?% in bladder, respectively. The corresponding prevalence rates were 9 and 2?% (rectum) and 18 and 21?% (bladder), respectively.

Conclusion

Late side effects after cervical cancer radiotherapy are partially reversible, but their time course is organ-dependent. The combined presentation of incidence- and prevalence rates provides the most comprehensive information.     

In vivo dosimetry with semiconductors in medium dose rate (MDR) brachytherapy for cervical cancer

Purpose

This study was performed to evaluate the role of in vivo dosimetry with semiconductor detectors in gynaecological medium dose rate brachytherapy, and to compare the actual doses delivered to organs at risk (as measured using in vivo dosimetry) with those calculated during treatment planning.

Materials and methods

Doses to the rectum and bladder were measured in a group of patients with cervical carcinoma using semiconductor detectors and compared to the doses calculated using a treatment planning system. 36 applications of brachytherapy at dose rates of 1.8–2.3 Gy/h were performed in the patients.

Results

The mean differences between the measured and calculated doses were 3 % for the rectum and 11 % for the bladder.

Conclusions

The main reason for the differences between the measured and calculated doses was patient movement. To reduce the risk of large errors in the dose delivered, in vivo dosimetry should be performed in addition to treatment planning system computations.     

Pretreatment metabolic tumour volume is predictive of disease-free survival and overall survival in patients with oesophageal squamous cell carcinoma

Purpose

It has been suggested that FDG PET has predictive value for the prognosis of treated oesophageal carcinoma. However, the studies reported in the literature have shown discordant results. The aim of this study was to determine whether pretherapy quantitative metabolic parameters correlate with patient outcomes.

Methods

Included in the study were 67 patients with a histological diagnosis of oesophageal squamous cell carcinoma. Each patient underwent ¹⁸F-FDG PET (4.5 MBq/kg) before chemoradiotherapy. Quantitative analysis was performed using the following parameters: age, weight loss, location, N stage, OMS performance status, MTV_p and MTV_p′ (metabolic tumour volume determined by two different physicians), MTV_40% (volume for a threshold of 40 % of SUVmax), MTV_a (volume automatically determined with a contrast-based adaptive threshold method), SUVmax, SUVmean and TLG (total lesion glycolysis).

Results

MTV_p and MTV_40% were highly correlated (Pearson’s index 0.92). SUVmean_p and SUVmean_40% were also correlated (Pearson’s index 0.86), as were TLG_p and TLG_40% (Pearson’s index 0.98). Similarly, the parameters obtained with the adaptive threshold method (MTV_a, SUVmean_a and TLG_a) were correlated with those obtained manually (MTV_p, SUVmean_p and TLG_p). The manual metabolic tumour volume determination (MTV_p and MTV_p′) was reproducible. Multivariate analysis for disease-free survival (DFS) showed that a larger MTV_p was associated with a shorter DFS (p?=?0.004) and that a higher SUVmax was associated with a longer DFS (p?=?0.02). Multivariate analysis for overall survival (OS) showed that a larger MTV_p was associated with a shorter OS (p?=?0.01) and that a tumour in the distal oesophagus was associated with a longer OS (p?=?0.005). The associations among the other parameters were not statistically significant.

Conclusion

Metabolic tumour volume is a major prognostic factor for DFS and OS in patients with oesophageal squamous cell carcinoma. Higher SUVmax values were paradoxically associated with longer survival. The location of the tumour also appeared to affect prognosis.     

Physical and clinical implications of radiotherapy treatment of prostate cancer using a full bladder protocol

Purpose

To assess the dosimetric and clinical implication when applying the full bladder protocol for the treatment of the localized prostate cancer (PCA).

Patients and Methods

A total of 26 consecutive patients were selected for the present study. Patients underwent two series of CT scans: the day of the simulation and after 40 Gy. Each series consisted of two consecutive scans: (1) full bladder (FB) and (2) empty bladder (EB). The contouring of clinical target volumes (CTVs) and organs at risk (OAR) were compared to evaluate organ motion. Treatment plans were compared by dose distribution and dose?Cvolume histograms (DVH).

Results

CTV shifts were negligible in the laterolateral and superior?Cinferior directions (the maximum shift was 1.85 mm). Larger shifts were recorded in the anterior?Cposterior direction (95% CI, 0.83?C4.41 mm). From the dosimetric point of view, shifts are negligible: the minimum dose to the CTV was 98.5% (median; 95%CI, 95?C99%). The potential advantage for GU toxicity in applying the FB treatment protocol was measured: the ratio between full and empty bladder dose?Cvolume points (selected from our protocol) is below 0.61, excluding the higher dose region where DVHs converge.

Conclusion

Having a FB during radiotherapy does not affect treatment effectiveness, on the contrary it helps achieve a more favorable DVH and lower GU toxicities.     

Predictive Value of Preoperative Volume-Based 18F-2-Fluoro-2-Deoxy-<Emphasis Type="SmallCaps">d</Emphasis>-Glucose Positron Emission Tomography/Computed Tomography Parameters in Patients with Resectable Lung Adenocarcinoma

Purpose

This study aimed to investigate the prognostic value of metabolic tumor volume (MTV) and total lesion glycolysis (TLG), which are volume-based PET parameters, using ¹⁸F-2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in patients with surgically resectable lung adenocarcinoma.

Methods

We retrospectively evaluated 149 patients with lung adenocarcinoma who underwent ¹⁸F-FDG PET/CT before surgical resection. Maximum standardized uptake value (SUVmax), MTV, and TLG of the primary tumor with threshold value of SUVmax 30, 40, and 50% were calculated, respectively. To compare the predictive performance of volume-based PET parameters, recurrence-free survival was assessed using the Kaplan-Meier method.

Results

The study included 70 males and 79 females with an average age of 65.8 years. The median follow-up time was 45.4 months. Recurrence was observed in 53 patients (35.6%). The mean?±?SD SUVmax, MTV_30%, and TLG_30% of the entire cohort were 4.79?±?2.94, 19.45?±?24.85, and 56.43?±?101.88, respectively. The cut-off values of MTV_30% and TLG_30% for recurrence were 11.07 ad 30.56, respectively. The 1-year recurrence-free survival (RFS) rate was 96.5% in low-MTV_30% patients compared with 86.2% in high-MTV_30% patients (p?=?0.018) and 96.0% in low-TLG_30% patients compared with 88.5% in high-TLG_30% patients (p?<?0.001). On univariate and multivariate analysis, TLG_30% (HR, 2.828, p?<?0.001; HR, 2.738, p?<?0.001, respectively) was an independent prognostic factor for predicting recurrence-free survival (RFS).

Conclusion

TLG_30% value was observed to be a significant prognostic factor for RFS in patients with lung adenocarcinoma treated by surgical resection.

     

Quasi-VMAT in high-grade glioma radiation therapy

Purpose

To compare a quasi-volumetric modulated arc therapy (qVMAT) with three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) for the treatment of high-grade gliomas. The qVMAT technique is a fast method of radiation therapy in which multiple equispaced beams analogous to those in rotation therapy are radiated in succession.

Patients and methods

This study included 12 patients with a planning target volume (PTV) that overlapped at least one organ at risk (OAR). 3D-CRT was planned using 2–3 non-coplanar beams, whereby the field-in-field technique (FIF) was used to divide each field into 1–3 subfields to shield the OAR. The qVMAT strategy was planned with 15 equispaced beams and IMRT was planned using 9 beams with a total of 80 segments. Inverse planning for qVMAT and IMRT was performed by direct machine parameter optimization (DMPO) to deliver a homogenous dose distribution of 60 Gy within the PTV and simultaneously limit the dose received by the OARs to the recommended values. Finally, the effect of introducing a maximum dose objective (max. dose <?54 Gy) for a virtual OAR in the form of a 0.5 cm ring around the PTV was investigated.

Results

The qVMAT method gave rise to significantly improved PTV_95% and conformity index (CI) values in comparison to 3D-CRT (PTV_95%?=?90.7?% vs. 82.0?%; CI?=?0.79 vs. 0.74, respectively). A further improvement was achieved by IMRT (PTV_95%?=?94.4?%, CI?=?0.78). In qVMAT and IMRT, the addition of a 0.5 cm ring around the PTV produced a significant increase in CI (0.87 and 0.88, respectively), but dosage homogeneity within the PTV was considerably reduced (PTV_95%?=?88.5?% and 92.3?%, respectively). The time required for qVMAT dose delivery was similar to that required using 3D-CRT.

Conclusion

These findings suggest that qVMAT should be preferred to 3D-CRT for the treatment of high-grade gliomas. The qVMAT method could be applied in hospitals, for example, which have limited departmental resources and are not equipped with systems capable of VMAT delivery.     

Variability of 18F-FDG-positive lung lesion volume by thresholding

Objectives

To assess the variability of ¹⁸F-FDG-positive volume measurements in lung cancer patients, obtained with different fixed percentages of maximum standard uptake value (SUVmax) thresholds.

Methods

PET dynamic acquisition involving ten frames was performed within 60–110 min post-injection in eight patients. In each lesion (n?=?11), volume was automatically outlined in each frame with fixed 40–50–60–70 % of the SUVmax thresholds. Thus, ten volume values for each threshold (V_{40–50–60–70}) were available to calculate relative SD (SDr), and hence relative measurement error (MEr) and repeatability (R). Dependence on SUVmax variability was also assessed.

Results

Mean SDr (<SDr>; %) of volume estimates was found to strongly correlate with threshold value (T; %): <SDr>?= 1.626?×?exp(0.044?×?T) (r?=?0.999; P?<?0.01). MEr and R for V₄₀ were found to be (95 % CL) 18.9 % and 26.7 %. For all fixed thresholds, in successive frames of an arbitrary lesion, volume estimate inversely correlated with SUVmax (P?≤?0.02).

Conclusions

A formula allows estimation of the variability of ¹⁸F-FDG-positive volumes provided by any fixed percentage of SUVmax threshold, and hence by any thresholding method. It only necessitates conversion of the threshold value into the SUVmax percentage in order to aid quick estimation of volume variability magnitude in current clinical practice.

Key Points

? In oncology, PET is widely used to assess the metabolic active volume ? This paper investigates the variability of ¹⁸ F-FDG-positive volumes by thresholding ? A formula is available for estimating this variability for any thresholding method ? For 40 %-SUVmax threshold, measurement error and repeatability are (95 % CL) 18.9 %/26.7 %     

HDR brachytherapy: an option for preventing nonmalignant obstruction in patients after lung transplantation

Purpose

Interventional bronchoscopy is the main treatment modality in managing benign airway obstructions following lung transplantation. We analyzed the effect of intraluminal brachytherapy on preventing recurrence of hyperplastic tissue.

Patients and methods

From September 2002 to September 2004, a total of 24 intraluminal brachytherapy applications were carried out on 12 lung transplant patients in 15 different locations. A single dose of 3?Gy was calculated at a 5-mm distance from the catheter surface; the target volume included a stenosis plus safety interval of 0.5?C1.0?cm.

Results

All patients had a mean 10.6 local interventions (Argon plasma coagulation, balloon dilatations, stenting) over 4.4?months before the first application of endobronchial brachytherapy, with a mean amount of 2.4 applications per month. The mean forced expiratory volume in 1?s (FEV1) was 2,219?ml in the 3?months before application of brachytherapy. After endobronchial brachytherapy, all patients experienced improvement in clinical status and respiratory function. The mean level of FEV1 in the 3?months after application was 2,435?ml (p?=?0.02), and the number of invasive interventions dropped to a mean rate of 5.2 interventions in the 5.1?months after the first intervention, with an amount of 1 application per month. No treatment-related complications were seen. Four patients were treated twice, 1?patient three times, and 1?patient four times at the same localization.

Conclusions

Recurrent symptomatic benign airway obstruction from hyperplastic tissue in the bronchus after lung transplantation can be successfully treated with intraluminal high-dose-rate brachytherapy with a dose of 3?Gy at a 5-mm distance from the catheter surface and a longitudinal safety margin of 1?cm.     

Node-positive left-sided breast cancer: does VMAT improve treatment plan quality with respect to IMRT?

Purpose

The aim of the present work was to explore plan quality and dosimetric accuracy of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for lymph node-positive left-sided breast cancer.

Methods

VMAT and IMRT plans were generated with the Pinnacle³ V9.0 treatment planning system for 10 lymph node-positive left-sided breast cancer patients. VMAT plans were created using a single arc and IMRT was performed with 4 beams using 6, 10, and 15 MV photon energy, respectively. Plans were evaluated both manually and automatically using ArtiView?. Dosimetric plan verification was performed with a 2D ionization chamber array placed in a full scatter phantom.

Results

Photon energy had no significant influence on plan quality for both VMAT and IMRT. Large variability in low doses to the heart was found due to patient anatomy (range V_5 Gy 26.5–95?%). Slightly more normal tissue dose was found for VMAT (e.g., V_Tissue30%?=?22?%) than in IMRT (V_Tissue30%?=?18?%). The manual and ArtiView? plan evaluation coincided very accurately for most dose metrics (difference <?1?%). In VMAT, 96.7?% of detector points passed the 3?%/3 mm gamma criterion; marginally better accuracy was found in IMRT (98.3?%).

Conclusion

VMAT for node-positive left-sided breast cancer retains target homogeneity and coverage when compared to IMRT and allows maximum doses to organs at risk to be reduced. ArtiView? enables fast and accurate plan evaluation.     

Cardiovascular magnetic resonance imaging assessment of diastolic dysfunction in a population without heart disease: a gender-based study

Objectives

Asymptomatic left ventricular (LV) diastolic dysfunction is increasingly recognised as an important diagnosis. Our goal was to study the prevalence and gender differences in subclinical LV diastolic dysfunction, using cardiovascular magnetic resonance imaging (CMR) at 3 T.

Methods

We prospectively studied 48 volunteers (19 male and 29 female, mean age 49?±?7 years) with no evidence of cardiovascular disease. We used CMR to measure left atrium (LA) and LV volumes, LV peak filling rate and transmitral flow.

Results

The overall prevalence of LV diastolic dysfunction in our cohort varied between 20 % (based on evaluation of LV filing profiles) and 24 % (based on the evaluation of the transmitral flow). The prevalence of diastolic dysfunction was higher in men than in women, independently of the criteria used (P between 0.004 and 0.022). Indexed LV end-diastolic volume, indexed LV stroke volume, indexed LV mass, indexed LA minimum volume and indexed LA maximum volume were significantly greater in men than in women (P?<?0.05). All the subjects had LV ejection fractions within the normal range.

Conclusions

It is clinically feasible to study diastolic flow and LV filling with CMR. CMR detected diastolic dysfunction in asymptomatic men and women.

Key Points

? CMR imaging offers new possibilities in assessing left ventricular diastolic function. ? The prevalence of diastolic dysfunction is higher in men than in women. ? The prevalence of some diastolic dysfunction in a normal population is 24 %.     

The association of haemoglobin A1C levels with the clinical and CT characteristics of Klebsiella pneumoniae liver abscesses in patients with diabetes mellitus

Objectives

To compare the characteristics of Klebsiella pneumoniae liver abscesses (KPLA) in diabetic patients with different levels of glycaemic control.

Methods

The institutional review board approved this retrospective study. A total of 221 patients with KPLA were included. Clinical features of KPLA were compared. We divided the 120 diabetic patients with KPLA into three subgroups based on haemoglobin A_1C (HbA_1C) concentration (good, HbA_1C?≤?7.0 %; suboptimal, 7.0 %?<?HbA_1C?≤?9.0 %; poor, HbA_1C?>?9.0 %). In this study, we used a semiautomated quantitative method to assess the gas and total abscess volumes in KPLA. Statistical analysis was performed with the chi-squared test and one-way analysis of variance.

Results

The mortality rate did not significantly differ between the nondiabetic and diabetic groups. However, patients with poor glycaemic control had significantly more complications and therefore a longer hospital stay (P?<?0.05). In our study, CT and quantitative analyses found that patients in the group with poor glycaemic control had a significantly higher incidence of gas formation and hepatic venous thrombophlebitis and a higher gas-to-abscess volume ratio than patients with suboptimal and good glycaemic control (P?<?0.05).

Conclusions

Diabetic patients with a high HbA_1C concentration (>9.0 %) have an association with hepatic venous thrombophlebitis, gas formation and metastatic infection complications associated with KPLA.

Key Points

? Poorly controlled diabetes is associated with complications in Klebsiella pneumoniae liver abscesses. ? Hepatic venous thrombosis and gas are important signs of metastatic infection. ? Hepatic venous thrombophlebitis is associated with 72.7 % of metastatic infections.