Jan Zizka

MRI-based Preplanning Using CT and MRI Data Fusion in Patients With Cervical Cancer Treated With 3D-based Brachytherapy: Feasibility and Accuracy Study

PURPOSE Magnetic resonance imaging (MRI)-assisted radiation treatment planning enables enhanced target contouring. The purpose of this study is to analyze the feasibility and accuracy of computed tomography (CT) and MRI data fusion for MRI-based treatment planning in an institution where an MRI scanner is not available in the radiotherapy department. METHODS AND MATERIALS The registration inaccuracy of applicators and soft tissue was assessed in 42 applications with CT/MRI data fusion. The absolute positional difference of the center of the applicators was measured in four different planes from the top of the tandem to the cervix. Any inaccuracy of registration of soft tissue in relation to the position of applicators was determined and dose-volume parameters for MRI preplans and for CT/MRI fusion plans with or without target and organs at risk (OAR) adaptation were evaluated. RESULTS We performed 6,132 measurements in 42 CT/MRI image fusions. Median absolute difference of the center of tandem on CT and MRI was 1.1 mm. Median distance between the center of the right ovoid on CT and MRI was 1.7 and 1.9 mm in the laterolateral and anteroposterior direction, respectively. Corresponding values for the left ovoid were 1.6 and 1.8 mm. Rotation of applicators was 3.1°. Median absolute difference in position of applicators in relation to soft tissue was 1.93, 1.50, 1.05, and 0.84 mm in the respective transverse planes, and 1.17, 1.28, 1.27, and 1.17 mm in selected angular directions. The dosimetric parameters for organs at risk on CT/MRI fusion plans without OAR adaptation were significantly impaired whereas the target coverage was not influenced. Planning without target adaptation led to overdosing of the target volume, especially high-risk clinical target volume--D₉₀ 88.2 vs. 83.1 (p < 0.05). CONCLUSIONS MRI-based preplanning with consecutive CT/MRI data fusion can be safe and feasible, with an acceptable inaccuracy of soft tissue registration.

Association of oesophageal atresia, anophthalmia and renal duplex

The authors report on a neonate with oesophageal atresia and tracheo-oesophageal fistula associated with bilateral anophthalmia and duplication of the left kidney. The combination of oesophageal atresia and anophthalmia has been reported in the literature several times before. We here report a boy with this disorder, with the additional feature of renal duplex. A term baby boy born spontaneously to a 25-year-old mother was admitted to our department on the 2nd day of life because of suspected oesophageal atresia and fused eyelids. The family history did not reveal any malformations. There was no history of abortions, miscarriages or consanguinity. The prenatal period was normal except for maternal penicillin treatment of acute tonsillitis in the 2nd month of gestation and mild respiratory infection in the 4th month of gestation. At birth, the baby had apparently fused eyelids without palpable eyeballs. Oral secretions were excessive. Attempts to pass a feeding tube failed. His genitals were normal without hypospadias or cryptorchism. Apgar scores were 9, 9, and 10 at 1.5 and 10 min, respectively. Birth weight was 3480 g, length was 52 cm and occipital-frontal-circumference was 32 cm. Radiological investigation revealed oesophageal atresia/Vogt type IIIB/ with distal tracheo-oesophageal fistula, both repaired within 24 h after admission. He received total parenteral nutrition until the 3rd postoperative day, at which time oral feeding was begun. MRI was performed on the 16th day of life and disclosed aplasia of the eyeballs, optic nerves and chiasm (Fig. 1). Mild dysgenesis of the corpus callosum was also noted. Moreover, duplication of the left kidney was detected on abdominal ultrasound whereas the right kidney was reported as normal. Diagnostic tests included a normal echocardiogram and chromosome analysis revealed a normal 46,XY karyotype. Despite a special rehabilitation programme, the boy showed a significant delay in psychomotor development at the age of 18 months which was greater than that in other blind children of the same age. Similar cases of associated anophthalmia and oesophageal atresia (McKusick 600992) have been reported in the literature. The first such case, described I. Petrackova (&) Æ O. Pozler Æ Z. Kokstein Department of Paediatrics, University Hospital Hradec Kralove, Czech Republic E-mail: petrackova.irena@post.cz

Iterative reconstruction of pulmonary MDCT angiography: Effects on image quality, effective dose and estimated organ dose to the breast

AIMS To compare the image characteristics, effective dose and estimated organ dose to the female breast in pulmonary MDCT angiography (MDCTA), reconstructed with either standard filtered back projection (FBP), or iterative reconstruction in image space (IRIS). METHODS Pulmonary MDCTA performed in 116 females (age 18 - 77 years; body mass index 15 - 48) was reconstructed with FBP (n=52) or IRIS (n=64). Scans were acquired on a 128-row MDCT system using automatic tube current modulation, 100 kV tube voltage, and a quality reference mAs value of 120 (FBP) and 80 (IRIS). Dose was calculated from CT dose index (CTDIvol) and dose length product (DLP) values utilising ImPACT software. Image noise was measured within the pulmonary artery. Qualitative visual assessment of the scans was performed (1=negligible noise, 5=noise obscuring diagnostic information). RESULTS The average CTDIvol yielded 4.33 mGy for FBP and 3.54 mGy for IRIS, respectively (18.2% decrease). The average effective scan dose was 2.73±0.57 mSv (FBP) and 2.29±0.68 mSv (IRIS), respectively (16.1% decrease). The estimated average organ dose to the breast decreased from 5.1±1.1 mGy (FBP) to 4.2±1.2 mGy (IRIS, 17.6% decrease). No non-diagnostic scans (score 5) were encountered in either group. Significant improvement in image noise levels (P<0.01) and subjective image quality (P<0.02) were noted in IRIS group. CONCLUSION Pulmonary MDCTA utilizing a 100 kV technique, automatic tube current modulation, and iterative image reconstruction offers robust results in routine conditions among an unselected female population, with breast doses being comparable to two-view digital mammography. Moreover, iterative reconstruction offers improvements in both image noise and visual perception of the scans, thus suggesting a potential for further dose reduction.

Reduction of effective dose and organ dose to the eye lens in head MDCT using iterative image reconstruction and automatic tube current modulation.

AIMS To compare the effective and eye lens radiation dose in helical MDCT brain examinations using automatic tube current modulation in conjunction with either standard filtered back projection (FBP) technique or iterative reconstruction in image space (IRIS). METHODS Of 400 adult brain MDCT examinations, 200 were performed using FBP and 200 using IRIS with the following parameters: tube voltage 120 kV, rotation period 1 second, pitch factor 0.55, automatic tube current modulation in both transverse and longitudinal planes with reference mAs 300 (FBP) and 200 (IRIS). Doses were calculated from CT dose index and dose length product values utilising ImPACT software; the organ dose to the lens was derived from the actual tube current-time product value applied to the lens. Image quality was assessed by two independent readers blinded to the type of image reconstruction technique. RESULTS The average effective scan dose was 1.47±0.26 mSv (FBP) and 0.98±0.15 mSv (IRIS), respectively (33.3% decrease). The average organ dose to the eye lens decreased from 40.0±3.3 mGy (FBP) to 26.6±2.0 mGy (IRIS, 33.5% decrease). No significant change in diagnostic image quality was noted between IRIS and FBP scans (P=0.17). CONCLUSION Iterative reconstruction of cerebral MDCT examinations enables reduction of both effective and organ eye lens dose by one third without signficant loss of image quality.

Clinical Use of Magnetic Resonance Imaging for the Diagnosis of Acute Myocardial Infarction in the Survivors of Cardiac Arrest

The ventricular arrhythmias with underlying coronary artery disease are a leading cause of sudden cardiac death (SCD). While the SCD survivors with proven AMI are considered to be at low risk of SCD recurrence, those without the evidence of AMI represent a high risk group that benefits from implantable cardioverter defibrillator. Therefore, the evaluation of SCD survivors for the presence of acute myocardial infarction (AMI) as a triggering factor of cardiac arrest is essential. In SCD survivors, the use of the standard diagnostic criteria of AMI may be difficult, as both serum cardiac biomarkers and electrocardiogram can be influenced by previous cardiac arrest. A novel technique that may be used for the diagnosis of AMI is magnetic resonance imaging (MRI). We report its use in four patients after cardiopulmonary resuscitation where the diagnosis of AMI could not be definitely established or excluded by means of other diagnostic procedures.