Could new reconstruction CT techniques challenge MRI for the detection of brain metastases in the context of initial lung cancer staging?

OBJECTIVES: To evaluate the diagnostic performance of brain CT images reconstructed with a model-based iterative algorithm performed at usual and reduced dose. METHODS: 115 patients with histologically proven lung cancer were prospectively included over 15 months. Patients underwent two CT acquisitions at the initial staging, performed on a 256-slice MDCT, at standard (CTDIvol: 41.4 mGy) and half dose (CTDIvol: 20.7 mGy). Both image datasets were reconstructed with filtered back projection (FBP) and iterative model-based reconstruction (IMR) algorithms. Brain MRI was considered as the reference. Two blinded independent readers analysed the images. RESULTS: Ninety-three patients underwent all examinations. At the standard dose, eight patients presented 17 and 15 lesions on IMR and FBP CT images, respectively. At half-dose, seven patients presented 15 and 13 lesions on IMR and FBP CT images, respectively. The test could not highlight any significant difference between the standard dose IMR and the half-dose FBP techniques (p-value = 0.12). MRI showed 46 metastases on 11 patients. Specificity, negative and positive predictive values were calculated (98.9-100 %, 93.6-94.6 %, 75-100 %, respectively, for all CT techniques). CONCLUSION: No significant difference could be demonstrated between the two CT reconstruction techniques. KEY POINTS: • No significant difference between IMR100 and FBP50 was shown. • Compared to FBP, IMR increased the image quality without diagnostic impairment. • A 50 % dose reduction combined with IMR reconstructions could be achieved. • Brain MRI remains the best tool in lung cancer staging.

Low contrast detectability and spatial resolution with model-based Iterative reconstructions of MDCT images: a phantom and cadaveric study.

OBJECTIVES: To compare image quality [low contrast (LC) detectability, noise, contrast-to-noise (CNR) and spatial resolution (SR)] of MDCT images reconstructed with an iterative reconstruction (IR) algorithm and a filtered back projection (FBP) algorithm. METHODS: The experimental study was performed on a 256-slice MDCT. LC detectability, noise, CNR and SR were measured on a Catphan phantom scanned with decreasing doses (48.8 down to 0.7 mGy) and parameters typical of a chest CT examination. Images were reconstructed with FBP and a model-based IR algorithm. Additionally, human chest cadavers were scanned and reconstructed using the same technical parameters. Images were analyzed to illustrate the phantom results. RESULTS: LC detectability and noise were statistically significantly different between the techniques, supporting model-based IR algorithm (p < 0.0001). At low doses, the noise in FBP images only enabled SR measurements of high contrast objects. The superior CNR of model-based IR algorithm enabled lower dose measurements, which showed that SR was dose and contrast dependent. Cadaver images reconstructed with model-based IR illustrated that visibility and delineation of anatomical structure edges could be deteriorated at low doses. CONCLUSION: Model-based IR improved LC detectability and enabled dose reduction. At low dose, SR became dose and contrast dependent. KEY POINTS: • Model- based Iterative Reconstruction improves detectability of low contrast object. • With model- based Iterative Reconstruction, spatial resolution is dose and contrast dependent. • Model-based Iterative Reconstruction algorithms enable improved IQ combined with dose-reduction possibilities. • Improvement of SR and LC detectability on the same IMR data set would reduce reconstructions.

EORTC Nomograms and Risk Groups for Predicting Recurrence, Progression, and Disease-specific and Overall Survival in Non-Muscle-invasive Stage Ta-T1 Urothelial Bladder Cancer Patients Treated with 1-3 Years of Maintenance Bacillus Calmette-Guérin.

BACKGROUND: There are no prognostic factor publications on stage Ta-T1 non-muscle-invasive bladder cancer (NMIBC) treated with 1-3 yr of maintenance bacillus Calmette-Guérin (BCG). OBJECTIVE: To determine prognostic factors in NMIBC patients treated with 1-3 yr of BCG after transurethral resection of the bladder (TURB), to derive nomograms and risk groups, and to identify high-risk patients who should be considered for early cystectomy. DESIGN, SETTING, AND PARTICIPANTS: Data for 1812 patients were merged from two European Organization for Research and Treatment of Cancer randomized phase 3 trials in intermediate- and high-risk NMIBC. INTERVENTION: Patients received 1-3 yr of maintenance BCG after TURB and induction BCG. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Prognostic factors for risk of early recurrence and times to late recurrence, progression, and death were identified in a training data set using multivariable models and applied to a validation data set. RESULTS AND LIMITATIONS: With a median follow-up of 7.4 yr, 762 patients recurred; 173 progressed; and 520 died, 83 due to bladder cancer (BCa). Statistically significant prognostic factors identified by multivariable analyses were prior recurrence rate and number of tumors for recurrence, and tumor stage and grade for progression and death due to BCa. T1G3 patients do poorly, with 1- and 5-yr disease-progression rates of 11.4% and 19.8%, respectively, and 1- and 5-yr disease-specific death rates of 4.8% and 11.3%. Limitations include lack of repeat transurethral resection in high-risk patients and exclusion of patients with carcinoma in situ. CONCLUSIONS: NMIBC patients treated with 1-3 yr of maintenance BCG have a heterogeneous prognosis. Patients at high risk of recurrence and/or progression do poorly on currently recommended maintenance schedules. Alternative treatments are urgently required. PATIENT SUMMARY: Non-muscle-invasive bladder cancer patients at high risk of recurrence and/or progression do poorly on currently recommended bacillus Calmette-Guérin maintenance schedules, and alternative treatments are urgently required. TRIAL REGISTRATION: Study 30911 was registered with the US National Cancer Institute clinical trials database (protocol ID: EORTC 30911). Study 30962 was registered at ClinicalTrials.gov, number NCT00002990; http://clinicaltrials.gov/ct2/show/record/NCT00002990.