Cyclic voiding cystourethrography: Is vesicoureteral reflux missed with standard voiding cystourethrography?

Vesicoureteral reflux (VUR) may occur intermittently and cyclic voiding cystourethrography (VCUG) can enhance the ability of the method to detect reflux. We undertook this prospective study to assess how often VUR may occur intermittently during VCUG and to evaluate the reliability of the method by performing cyclic VCUG. Two hundred seventy-five children younger than 2 years underwent two cycles of VCUG. Ninety-seven refluxing kidney-ureter units (KUU) from 68 children were identified during the two cycles. In 18 children VUR was demonstrated in the first, and in 50 children only in the second, cycle. Discrepancy between the two cycles regarding the presence and/or grade of VUR was observed in 85 KUU from 63 of 275 children (23%). In 21 of these 63 children VUR was > or = grade III. In the presence of reflux in the first cycle, discordant findings in the second cycle were found in 11 of 23 KUU (48%) or in 13 of 18 children (72.2%). In the absence of VUR in the first cycle, the second cycle disclosed reflux in 50 of 257 children (19.5%). In conclusion, intermittent VUR occurred in up to 23% of children undergoing VCUG. In more than one-third of them VUR was of major degree. Cyclic VCUG can enhance the ability of the method to detect and grade reflux.     

What are the risks from medical X-rays and other low dose radiation?

The magnitude of the risks from low doses of radiation is one of the central questions in radiological protection. It is particularly relevant when discussing the justification and optimization of diagnostic medical exposures. Medical X-rays can undoubtedly confer substantial benefits in the healthcare of patients, but not without exposing them to effective doses ranging from a few microsieverts to a few tens of millisieverts. Do we have any evidence that these levels of exposure result in significant health risks to patients? The current consensus held by national and international radiological protection organizations is that, for these comparatively low doses, the most appropriate risk model is one in which the risk of radiation-induced cancer and hereditary disease is assumed to increase linearly with increasing radiation dose, with no threshold (the so-called linear no threshold (LNT) model). However, the LNT hypothesis has been challenged both by those who believe that low doses of radiation are more damaging than the hypothesis predicts and by those who believe that they are less harmful, and possibly even beneficial (often referred to as hormesis). This article reviews the evidence for and against both the LNT hypothesis and hormesis, and explains why the general scientific consensus is currently in favour of the LNT model as the most appropriate dose-response relationship for radiation protection purposes at low doses. Finally, the impact of the LNT model on the assessment of the risks from medical X-rays and how this affects the justification and optimization of such exposures is discussed.     

Abdominal spiral CT in children: which radiation exposure is required?

We decided to test to what extent dose reduction is possible in abdominal spiral computed tomography (CT) in young children without loss of anatomic diagnostic information. A retrospective study was performed of 30 abdominal CT examinations of children aged 3 months to 7 years. These were divided into two groups: group A with reduced radiation exposure (tube current 50 mA, CT dose index CTDIFDA < or =0.83 mGy) and group B with standard radiation exposure (tube current > or =100 mA, CTDIFDA > or =1.66 mGy). Image quality was assessed using a four-part scale ('excellent', 'good', 'sufficient', 'poor') on visual image impression and visibility of 32 anatomical details. Five experienced radiologists read the CT scans independently who were blinded to the examination parameters. Differences in ranked data were evaluated with Wilcoxon's rank sum test. No difference between groups A and B was observed in visual image impression. Detail visibility was significantly lower in group A, but the differences were limited to right upper quadrant structures (portal vein, common bile duct, pancreatic head, adrenals) and to arterial branches. Significant differences in visibility rated as 'poor' were only found for the hepatic, splenic and renal arteries; all other structures showed no difference between groups A and B. A protocol with reduced radiation exposure (50 mA, CTDIFDA < or =0.83 mGy) allowed the demonstration of most anatomic structures in abdominal spiral CT in young children. For the precise demonstration of small details (e.g. structures of the right upper quadrant), a protocol with standard radiation exposure (> or =100 mAs) was superior.     

Second malignancies in children: the usual suspects?

The aim of this article is to provide an up to date review of second malignant neoplasms (SMN's) following treatment for childhood cancer, referring to their incidence, the role of genetic factors, and how the primary malignancy and treatment received influence the type, site and prognosis of SMN's. The role of genetic factors will be discussed as far as they impact upon a predisposition to later development of SMN's. The primary malignancies that have important associations with SMN's will then be discussed, in particular Hodgkin's disease, retinoblastoma and acute lymphoblastic leukaemia. The important second malignancies will be highlighted, including tumours of the CNS and thyroid, osteosarcoma, secondary acute myeloid leukaemia and melanoma. Emphasis will be put upon identifying which patients are most likely to suffer from these tumours. An important part of the article are case histories. These are provided in combination with illustrations as a useful adjunct to the text, with a particular emphasis on radiological features, diagnosis and screening. Finally, the important but different roles of causal agents, in particular chemotherapy and radiotherapy are highlighted.     

Second malignancies in children: the usual suspects?

The aim of this article is to provide an up to date review of second malignant neoplasms (SMN's) following treatment for childhood cancer, referring to their incidence, the role of genetic factors, and how the primary malignancy and treatment received influence the type, site and prognosis of SMN's. The role of genetic factors will be discussed as far as they impact upon a predisposition to later development of SMN's. The primary malignancies that have important associations with SMN's will then be discussed, in particular Hodgkin's disease, retinoblastoma and acute lymphoblastic leukaemia. The important second malignancies will be highlighted, including tumours of the CNS and thyroid, osteosarcoma, secondary acute myeloid leukaemia and melanoma. Emphasis will be put upon identifying which patients are most likely to suffer from these tumours. An important part of the article are case histories. These are provided in combination with illustrations as a useful adjunct to the text, with a particular emphasis on radiological features, diagnosis and screening. Finally, the important but different roles of causal agents, in particular chemotherapy and radiotherapy are highlighted.     

Postmortem radiography after unexpected death in neonates,infants, and children: should imaging be routine?

OBJECTIVE: The purpose of this study was to determine whether postmortem radiography of neonates, infants, and children provides additional information that is not detected at autopsy in cases of unexpected death. MATERIALS AND METHODS: Inclusion criteria for 106 consecutive postmortem skeletal surveys (1998-2000) were neonates, infants, and children 2 years old or younger with no preexisting medical condition to account for mortality. Pediatric radiologists interpreted all the radiographic examinations, which consisted of high-detail, collimated anteroposterior radiographs of the appendicular and axial skeleton, lateral radiographs of the axial skeleton, and oblique radiographs of the ribs. Imaging results were compared with those obtained from standard protocol autopsies on all children. Four categories of death were designated: homicide (i.e., abuse, n = 14), accidental (e.g., drowning, n = 28), natural (e.g., acute illness, n = 43), and undetermined (n = 21). RESULTS: The causes of death in the 14 child abuse victims were blunt force injuries to the intracranial (n = 11) and chest and abdominal (n = 1) areas; asphyxia (n = 1); and shaking injury (n = 1). In six (43%) of these 14 patients, radiography detected 26 extremity fractures that had not been detected at autopsy; four (67%) of these six patients had fractures of different ages that involved more than one extremity. All fractures carried a high index of suspicion of abuse. No skeletal injuries were found in cases of accidental, undetermined, and natural deaths. CONCLUSION: Postmortem radiography provides important additional information regarding the extent and chronicity of extremity trauma that may not be documented at autopsy. This finding supports the routine use of radiography in cases of suspected child abuse. Normal findings on postmortem skeletal radiography may help to distinguish cases of natural, accidental, and undetermined causes of death from those of abuse, aiding in the proper handling of these cases by medical and law enforcement personnel.     

Ocular injuries in basketball and baseball: what are the risks and how can we prevent them?

Ocular trauma is a frequent result of sports-related injury during basketball and baseball. A screening sideline examination should be performed immediately to assess vision and evaluate the severity of damage. The team physician should be able to treat minor injuries and identify vision-threatening trauma for immediate referral. Injuries range from minor, including corneal abrasion and foreign bodies, to more severe, including hyphema, orbital fracture, and globe rupture. Resultant damage may be vision-threatening and permanent. Most of these injuries can be prevented with full-time use of sport-specific protective eyewear. Physicians should recommend appropriate eye protection and counsel patients accordingly.     

Nutcracker and SMA syndromes: What is the normal SMA angle in children?

Objective

The nutcracker and superior mesenteric artery (SMA) syndromes are rare conditions where the left renal vein or duodenum may be compressed by an unusually acute angle between the SMA and aorta, although the normal angle in children is unknown. We measured the SMA angle to define the normal range in children.

Methods

We retrospectively measured SMA angles, left renal vein (LRV) distance, and duodenal distance (DD) in 205 consecutive pediatric abdominal CT. Total and visceral intra-abdominal fat at the level of the umbilicus were also assessed.

Results

Mean SMA angle was 45.6 ± 19.6° (range 10.6–112.9°), mean LRV distance was 8.6 ± 3.9 mm (range 2.0–28.6 mm) and mean DD was 11.3 ± 4.8 mm (range 3.6–35.3 mm). There was a significant but weak correlation between %visceral fat volume (%VF) and SMA angle (R = 0.30; p < 0.001), LRV distance (R = 0.37, p < 0.001) and DD (R = 0.32; p < 0.001).

Conclusion

There is a wide range of SMA angle, LRV and DD in normal children, which correlated weakly with visceral fat volume. Using a definition of SMA angle <25° would diagnose 9.3% of asymptomatic children with nutcracker syndrome, and using a DD definition of <8 mm would diagnose 20% with SMA compression. Our findings suggest exercising caution when attributing these rare syndromes to an absolute SMA angle.     

Molecular biology: the key to personalised treatment in radiation oncology?

We know considerably more about what makes cells and tissues resistant or sensitive to radiation than we did 20 years ago. Novel techniques in molecular biology have made a major contribution to our understanding at the level of signalling pathways. Before the “New Biology” era, radioresponsiveness was defined in terms of physiological parameters designated as the five Rs. These are: repair, repopulation, reassortment, reoxygenation and radiosensitivity. Of these, only the role of hypoxia proved to be a robust predictive and prognostic marker, but radiotherapy regimens were nonetheless modified in terms of dose per fraction, fraction size and overall time, in ways that persist in clinical practice today. The first molecular techniques were applied to radiobiology about two decades ago and soon revealed the existence of genes/proteins that respond to and influence the cellular outcome of irradiation. The subsequent development of screening techniques using microarray technology has since revealed that a very large number of genes fall into this category. We can now obtain an adequately robust molecular signature, predicting for a radioresponsive phenotype using gene expression and proteomic approaches. In parallel with these developments, functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) can now detect specific biological molecules such as haemoglobin and glucose, so revealing a 3D map of tumour blood flow and metabolism. The key to personalised radiotherapy will be to extend this capability to the proteins of the molecular signature that determine radiosensitivity.Molecular biology developments have, over the past 20 years, provided us with a remarkable array of techniques, enhancing our understanding of how tumour and normal tissues respond to radiation damage. As these techniques grow increasingly sophisticated, their application should, in theory, present opportunities to improve the effectiveness of radiotherapy.However, as we look at how radiotherapy is performed today we see a discipline founded on 100 years of practice-based, empirical development, recently enhanced by impressive advances in dose delivery and image-guided procedures. These developments have brought us to a point where dose deposition is already highly tailored, to a tolerance of ∼2% for most tissues of the body, which is much more accurate than any pharmaceutical agent. Yet, are we really delivering dose where it needs to go for maximal therapeutic gain?     

Are the arms and legs in competition for cardiac output?

Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value. Despite this similarity between arm and leg VO2max, when arm exercise is added to leg exercise, VO2max is not markedly elevated, which suggests a central or cardiac limitation. In fact, when intense arm exercise is added to leg exercise, leg blood flow at a given work rate is approximately 10% less than during leg exercise alone. Similarly, when intense leg exercise is added to arm exercise, arm blood flow and muscle oxygenation are reduced by approximately 10%. Such reductions in regional blood flow are mainly attributed to peripheral vasoconstriction induced by the arterial baroreflex to support the prevailing blood pressure. This putative mechanism is also demonstrated when the ability to increase cardiac output is compromised; during exercise, the prevailing blood pressure is established primarily by an increase in cardiac output, but if the contribution of the cardiac output is not sufficient to maintain the preset blood pressure, the arterial baroreflex increases peripheral resistance by augmenting sympathetic activity and restricting blood flow to working skeletal muscles.     

Ultrasound of the appendix in children: is the child too obese?

The negative influence of obesity on the detection rate of the appendix for US in adults has been reported. It has been assumed that obesity is a limiting factor in the detection of the appendix with US in children as well, but this has not yet been proven. The aim of our study was to evaluate whether nutritional condition (defined by the body mass index-for-age percentiles: BMI-FAP) influences the detection of the appendix in children on US. One hundred twenty-six children (65 girls and 61 boys) with a mean age of 11.4 years with clinically suspected acute appendicitis underwent ultrasound on a commercially available high-end machine (HDI 5000, ATL, Bothell, Wash.). The BMI was calculated, and children were divided in three weight groups in accordance with the BMI-FAP, and were correlated with US findings. Evaluation of the three weight groups in accordance with the BMI-FAP demonstrated significant differences (p=0.04) in the detection of the appendix. There was no statistical significance for the BMI, weight, height, and age solely for the detection of the appendix. In children there is a correlation between the nutritional condition as defined by the BMI-FAP and the detection of the appendix. Electronic Publication     

Should the justification of medical exposures take account of radiation risks from previous examinations?

With the growing availability of dose histories for patients, the question of whether previous diagnostic radiation exposures should affect decisions on future examinations is coming into sharper focus. This article discusses ways in which cumulative dose information may affect our thinking in justifying exposures. Based on a common tendency to see a connection between past and future events even where we know them to be independent—the gambler''s fallacy—we may find ourselves treating past risks as if they contribute to the present risk. We take the example of two patients scheduled for CT scans, one with no previous diagnostic radiation exposures, the other with a history of previous CT scans, to show that the risks, and justification process, are equivalent in both cases. For the patient with a history of diagnostic exposures, there are only two possibilities: either harm has been caused or there has been no effect. If previous CT examinations have not caused harm, then, as past risks, they are irrelevant. The patient is in precisely the same position with regard to risk as a patient with no dose history. If harm has been caused, avoiding further diagnostic exposures does not change this outcome; again in this case, a justified radiation examination should proceed. We argue that bringing dose history into the decision process for justifying examinations is contrary to our understanding of risk for low-dose radiation and, rather than improving patient safety, would unnecessarily restrict access to radiation-based diagnostic examinations.With the growing availability of dose histories for patients, the question of whether previous diagnostic radiation exposures should affect decisions on future diagnostic radiation examinations is coming into sharper focus. Durand et al,¹ in a recent article, highlight the danger of cumulative dose estimates affecting the justification of future exposures, emphasizing that histories have no place in a rational decision-making process. The argument that justification should not take account of past exposures follows from the stochastic risk model described by the linear no threshold (LNT) hypothesis. According to this model, the probability of a low-dose exposure causing cancer is proportional to the radiation dose and, crucially for the argument being made here, each exposure is a statistically independent event.^2,3 However, despite the logical difficulties Durand et al describe, there can be a strong temptation to include cumulative exposures in the decision-making process. In this article, we look at how cumulative dose information might erroneously affect our thinking in justifying exposures and, taking an example of CT scans, set out the counter argument. The argument refers to risks that are modelled stochastically and follows the LNT hypothesis for low-dose exposures. Cumulative dose in high-dose procedures, where repeat exposures in a short time frame may accumulate to exceed a deterministic threshold for a tissue or organ, follows a different risk process and are not considered as part of this discussion.It is important to draw a distinction between the imaging information and the radiation exposure from past radiographic examinations. The justification process includes careful consideration of the benefit of the examination and how it will contribute to a patient''s clinical management. A key step in this process is the consideration of previous imaging to establish whether the clinical question can be answered without recourse to further radiation exposure or with a lower dose diagnostic examination. In the examples outlined in this commentary, it is assumed that this part of the justification process has been completed.There can be a tendency, however, to treat past dose information in the same way as previous imaging and assume that it should play a role in whether or not the patient should have further imaging with ionising radiation. We know, for example, that five CT scans carry a greater risk than one CT scan. It may seem reasonable to take the risks of the previous four scans into account when justifying the fifth scan. As our thinking subtly shifts towards consideration of the previous scans, the fifth CT scan begins to seem a different proposition to the first CT scan. In the back of our minds, the risk associated with the fifth scan becomes, notionally at least, somehow conflated with the risks from the previous four scans.Part of the thinking here is based on a logical error, sometimes referred to as the gambler''s fallacy. We have a strong tendency to assume that past events have an influence on future events, even when we know that each event is independent. A common example used to illustrate this point is the toss of a coin. Assuming it is a fair coin, the chances of getting tails on a coin toss is 50–50. However, if we get tails, there can be an inclination to believe that on the second toss of the coin, the probability of tails coming up again is less than 50–50. But this is not the case. The coin has no “knowledge” of past events, and its chance of coming up heads remains 50–50, so long as it is a fair coin, regardless of the history. The fallacy of believing we are due heads after several throws resulting in tails (i.e. that the odds of getting heads has changed) is also a factor when we consider further radiographic exposures.Take the situation of a patient who is scheduled for a fifth CT scan. The gambler''s fallacy leads us to believe that patients getting their fifth CT scan are in a different position with regard to the risk for that scan than they were for their first CT scan. We are, in a sense, considering the risk of all five scans together, although four of those scans were in the past and have no bearing on the risk for the fifth scan that we are being asked to justify. Of course, if we were actually comparing the risk of all five scans to the risk of one scan, then five scans carry the higher risk. But we are not in this position. Justifying a fifth CT scan should not be confused with justifying five CT scans. A previous scan is relevant if it provides the diagnostic information we are looking for, thus abrogating the need for a new scan; there is no basis under LNT for considering a previous radiation exposure as a modifier to the risk for the current scan.The argument can be brought out more clearly with an example. Assume we have two patients of equal size who have been scheduled for the same examination on the same CT scanner using the same technique factors. The scan has been properly justified for each patient. Patient A is to have their first CT scan. Patient B has had four previous CT scans. For the purpose of this argument, we take the risk of inducing cancer from a CT scan to be a standard value for each scan, say 1 in 2000.For Patient A, who has not had previous scans, we have justified the CT scan, and the examination goes ahead.What about Patient B? The scan has been clinically justified, but there is hesitancy because of the previous scans. Should we consider these? Is it correct to treat these two patients differently because of the previous radiation dose to Patient B?There are two possible outcomes in terms of the radiation risk for Patient B after four CT scans. Treating each outcome in turn with regard to its relevance to the fifth scan, we get the following:The first possibility is that Patient B has not had cancer induced by the previous CT examinations. The patient''s chance of getting cancer from the new scan is entirely unaffected by this history (the patient might have got cancer from the previous scans, but in this case did not: those four CT scans and their attendant risks are now past). Just as on a fair die, all previous rolls have no bearing on the probable outcome of future rolls, so too with stochastic cancer induction: the past scans where cancer was not induced have no affect one way or the other on the new scan. The risk probability for the fifth scan is not altered. Patient B is at precisely the same risk as Patient A. Given that the risks are equivalent for both patients, we have no basis for proceeding differently on each patient.The second possibility is that Patient B has had cancer induced by one or more of the previous scans. The new CT scan has no impact on this outcome. If we proceed, there is a chance of causing harm as before; if we do not scan the patient, then they still have cancer from the previous scan, and they lose the benefit from the CT scan that we have not given them. So in this case, we should also proceed with the scan.We do not know which of the two situations pertains to Patient B, but according to the LNT model, it is one or the other of the two cases. And as we have shown, we should proceed with a justified CT in either case. Thus, under the present understanding of risk as a stochastic process for low-dose radiation, previous dose history should not influence the justification of future radiographic exposures.The example above is intentionally artificial. We assume that each CT scan delivers the same dose and that it carries the same simplified risk quoted. This allows us to concentrate on the point in question—whether the history of risk is relevant—without getting sidetracked by the complexities of dose calculations. It also keeps the point general. Our argument attempts to show that, as a general rule, taking account of risk from previous scans should not affect the justification process. The justification process already includes risk–benefit analysis and the consideration of alternate strategies, and rightly focuses on the particular examination in question.This article makes the case that including the history of radiation risks in the justification process is contrary to our understanding of risk for low-dose radiation. Allowing cumulative dose estimates to influence whether a patient should get a scan would be tantamount to introducing dose limits for patients and, rather than improving patient safety, would unnecessarily restrict access to radiation-based diagnostic examinations.     

Preparticipation Exams: Are They Worth the Time and Trouble?

Discussions of preparticipation exams for junior and senior high school athletes seem to produce more questions than answers: How often should the tests be given; where; by whom; are they cost effective?