Impact of Dose-Modified Protocols on Radiation Doses in Patients Undergoing CT Examinations following Image-Guided Catheter Placement.

PURPOSE: To investigate the impact of dose-modified (DM) scan protocols on decreasing radiation exposure from computed tomography (CT) scans obtained following image-guided catheter procedures. MATERIALS AND METHODS: In this retrospective analysis, between December 2012 and June 2014, 192 patients (mean age, 60.7 y; 102 men) who underwent abdomen/pelvis CT examinations for catheter placement follow-up were included. The standard-dose (SD) baseline CT parameters included tube potential of 120 kVp, tube current of 75-550 mA, and noise index (NI) of 18-22. Weight-based scan parameters applied for follow-up CT were based on two reconstruction algorithms: filtered back projection (FBP; 120 kVp, 75-350 mA, NI = 30) and iterative reconstruction technique (IRT; 100/120 kVp, 75-250/350 mA, NI = 35). Two readers reviewed image quality (IQ) of follow-up and baseline CT examinations for 22 randomly sampled patients. Radiation doses were retrieved by dose monitoring software. RESULTS: Compared with baseline, DM follow-up CT protocols enabled substantial (62.4%) dose reductions (mean CT dose indexes: 4.1 mGy at follow-up, 10.9 mGy at baseline; P < .0001). Doses were significantly lower for IRT follow-up CT examinations compared with FBP (mean CT dose indexes: IRT, 3.6 mGy; FBP, 4.6 mGy; P < .05). In 47 patients with more than one follow-up CT examination (mean, 3.1 examinations per patient; range, 2-6), the observed cumulative radiation dose (CRD) was 42.1% lower than the expected CRD (observed, 1,437.9 mGy·cm; expected, 2,483.6 mGy·cm; P < .0001). Subjective IQ scores were acceptable for follow-up CT examinations (follow-up, 3.6; baseline, 4; P < .05). CONCLUSIONS: DM CT examinations enable substantial dose reduction (62.4%) for each follow-up examination compared with SD baseline scans, without any IQ concerns. Use of IRT decreases dose by an additional 22%. The CRD is lowered by 42% in patients undergoing multiple DM follow-up CT examinations.

Advances in CT imaging for urolithiasis.

Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice.

Radiation Dose Consideration in Kidney Stone CT Examinations: Integration of Iterative Reconstruction Algorithms With Routine Clinical Practice.

OBJECTIVE: The objective of our study was to evaluate three commercially available iterative reconstruction (IR) algorithms-ASiR, iDOSE, and SAFIRE-and conventional filtered back projection (FBP) on image quality and radiation dose in kidney stone CT examinations. MATERIALS AND METHODS: During the 6-month study period, 684 unenhanced kidney stone CT examinations of consecutive adults were performed on 17 CT scanners (GE Healthcare [vendor 1], n = 12 scanners; Philips Healthcare [vendor 2], n = 2; Siemens Health-care [vendor 3], n = 3); these examinations were retrieved using dose-monitoring software (eXposure). A total of 347 kidney stone CT examinations were reconstructed using FBP, and 337 examinations were processed using IR (ASiR, n = 248; iDOSE, n = 50; SAFIRE, n = 39). The standard-dose scanning parameters for FBP scanners included a tube potential of 120 kVp, a tube current of 75-450 mA for vendor 1 and a Quality Reference mAs of 160-180 for vendor 3, and a slice thickness of 2.5 or 5 mm. The dose-modified protocol for the IR scanners included a higher noise index (1.4 times higher than the standard-dose FBP protocol) for vendor 1, a lower reference tube current-exposure time product for vendor 2 (150 reference mAs), and a lower Quality Reference mAs for vendor 3 (120 Quality Reference mAs). Three radiologists independently reviewed 60 randomly sampled kidney stone CT examinations for image quality, noise, and artifacts. Objective noise and attenuation were also determined. Size-specific dose estimates (SSDEs) were compared using ANOVA. RESULTS: Significantly higher subjective and objective measurements of image noise were found in FBP examinations compared with dose-modified IR examinations (p < 0.05). The radiation dose was substantially lower for the dose-modified IR examinations than the standard-dose FBP examinations (mean SSDE ± SD: 8.1 ± 3.8 vs 11.6 ± 3.6 mGy, respectively) (p < 0.0001), but the radiation dose was comparable among the three IR techniques (ASiR, 7.8 ± 3.1 mGy; iDOSE, 7.5 ± 1.9 mGy; SAFIRE, 7.6 ± 3.2 mGy) (p > 0.05). CONCLUSION: The three IRs enable 20-33% radiation dose reduction in kidney stone CT examinations compared with the FBP technique without any image quality concerns. The radiation dose and image quality were comparable among these three IR algorithms.

Experiences with the use of iteratively reconstructed dose-modified MDCT angiography examinations of living renal donors.

PURPOSE: To evaluate the performance of iteratively reconstructed (IR) dose-modified (DM) multidetector computed tomography (MDCT) angiography (CTA) examinations of renal donors in comparison to standard dose filtered back projection (FBP) images. MATERIALS AND METHODS: Eighty-five potential donors who underwent dual-phase CTA on 16-/64-MDCT scanners were retrospectively reviewed. Images from a 16-MDCT scanner were reconstructed with filtered back projection (group A, 47) and examinations from 64-MDCT with IR (group B, 38). Scan parameters were constant for both groups except for higher noise index (× 1.3) in group B. Images were interpreted for the relevant anatomy and IQ by 2 readers. Surgical report served as reference standard for operated kidneys, whereas for nonoperated kidneys, interobserver agreement was evaluated. RESULTS: Radiation dose was 36% lower in group B compared to group A. All CTA examinations were rated for diagnostic quality with comparable IQ scores. In 48 operated kidneys, 10 surgically confirmed vascular anomalies were correctly identified by both readers. In the remaining 122 nonoperated kidneys, there was an excellent interobserver agreement. CONCLUSIONS: Iteratively reconstructed technique preserves high image quality and diagnostic performance at significantly lower radiation doses in DM kidney donor CTA examinations.

Current status of imaging and emerging techniques to evaluate liver metastases from colorectal carcinoma.

Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. Liver is a common site of tumor spread and in approximately 30% of the cases; synchronous liver disease is present at the time of diagnosis. Early detection of liver metastases is crucial to appropriately select patients who may benefit from hepatic resection among those needing chemotherapy, to improve 5-year survival. Advances in imaging techniques have contributed greatly to the management of these patients. Multidetector computed tomography is the most useful test for initial staging and in posttreatment surveillance settings. Magnetic resonance imaging is considered superior to multidetector computed tomography and positron emission tomography for the detection and characterization of small lesions and for liver evaluation in the presence of background fatty liver changes. Positron emission tomography-computed tomography has a problem-solving role in the detection of distant metastasis and in posttreatment evaluation. The advanced imaging methods also serve a role in selecting appropriate patients for radiologically targeted therapies and in monitoring response to conventional and novel therapies.

Knowledge of medical students of Tehran University of Medical Sciences regarding plagiarism.

The core concept of plagiarism is defined as the use of other people's ideas or words without proper acknowledgement. Herein, we used a questionnaire to assess the knowledge of students of Tehran University of Medical Sciences (TUMS) regarding plagiarism and copyright infringement. The questionnaire comprised 8 questions. The first six questions of the questionnaire were translations of exercises of a book about academic writing and were concerning plagiarism in preparing articles. Questions number 7 and 8 (which were concerning plagiarism in preparing Microsoft PowerPoint slideshows and copyright infringement, respectively) were developed by the authors of the present study. The validity of the questionnaire was approved by five experts in the field of epidemiology and biostatistics. A pilot study consisting of a test and retest was carried to assess the reliability of the questionnaire. The sampling method was stratified random sampling, and the questionnaire was handed out to 74 interns of TUMS during July and August 2011. 14.9% of the students correctly answered the first six questions. 44.6% of the students were adequately familiar with proper referencing in Microsoft PowerPoint slideshows. 16.2% of the students understood what constitutes copyright infringement. The number of correctly answered questions by the students was directly proportionate to the number of their published articles. Knowledge of students of TUMS regarding plagiarism and copyright infringement is quite poor. Courses with specific focus on plagiarism and copyright infringement might help in this regard.

Seizure risk factors in shunted hydrocephalic patients.

OBJECTIVE: There are controversies about seizure risk factors in shunted hydrocephalic patients which can be due to having merged two different types of seizure (preshunt and postshunt seizures) in previous studies. Also, it is not known whether a considerable change in ventricular size after shunting can be a risk factor of postshunt seizures. METHODS: 150 hydrocephalic patients who underwent shunting from 2006 to 2011 in the Children's Hospital Medical Center in Tehran, Iran, were visited at least 1 year after shunting to assess risk factors of preshunt and postshunt seizures. Ventricular size was assessed by using a radiologic index of bifrontal ratio (BFR). RESULTS: Preshunt seizures were higher in patients with postinfectious hydrocephalus and intraventricular hemorrhage. Early shunting, history of shunt complications and shunt infection, and a high number of shunt revisions were significant risk factors for developing postshunt seizures. The change in BFR after shunting was not a significant risk factor of postshunt seizures. CONCLUSION: The difference between risk factors of preshunt seizures and postshunt seizures shows that they are two different types of seizures with different natures. Preshunt seizures are hard to prevent as they are related to the underlying disease of the brain or the etiology of hydrocephalus. However, postshunt seizures are related to the shunt and might be decreased by preventing shunt complications.

Triple lumbar dermal sinuses: unusual presentation of a typically solitary midline lesion.

BACKGROUND: Congenital dermal sinus is a type of closed spinal dysraphism caused by incomplete disjunction. The lesion occurs everywhere along neuraxis predominantly as a solitary midline sinus in the lumbosacral area. CASE HISTORY: The authors report on a 10-month-old girl with triple congenital dermal sinuses associated with dermoid tumors and intradural extension of one of them. DISCUSSION: Triple dermal sinuses of the lumbosacral area in a single patient have never been described previously. Incomplete disjunction is suggested to cause this abnormality thereafter the orifice may be divided to three sinuses and some mesenchymal tissues separated the two proximal sinuses to a paramedian location.

Mirror movement associated with neural tube defects.

OBJECTIVE: Association of mirror movements with special kinds of neural tube defects, particularly cranial dermal sinus and cervical myelomeningocele, is extremely rare. We have tried to explain the probable pathophysiology underlying this rare condition. CLINICAL PRESENTATION: Two cases are presented. Case 1: A right-handed 3-year-old boy brought to the outpatient clinic for evaluation of mirror movement had been operated on at 10 days of age to repair a cervical myelomeningocele. At examination, mirror movements were observed on both sides. Case 2: A right-handed 7-year-old boy referred for vertigo and occasional vomiting since 3 months of age. The mirror movements were present in the upper extremities, and reportedly had existed since early childhood. Brain magnetic resonance imaging disclosed the dermal sinus, tract, and midline dermoid tumor. CONCLUSION: To describe a meaningful association between mirror movements and congenital abnormalities in 2 cases reported here, we propose development of an abnormality in the cervical spinal cord (case 1) and cervicomedullary junction (case 2) associated with gross anomalies in the affected areas.