High-resolution MR imaging for nodal staging in rectal cancer: are there any criteria in addition to the size?

PURPOSE: MR staging of nodal metastases in patients with rectal cancer using criteria based on size, shape and signal intensity can be difficult, because > or =50% of the nodes are less than 5 mm in size. Therefore new MR criteria were evaluated to see whether it can improve the MR assessment of nodal metastases in rectal cancer patients. MATERIALS AND METHODS: Ninety-nine patients with primary rectal carcinoma underwent 1.5 T high-resolution MRI with a quadrature phased array coil. Among them, 75 patients who had undergone total mesorectal excision were enrolled in this study. An MR radiologist, blinded for the histological results, randomly recorded the characteristics of each detectable node (LN); common criteria such as short-axis diameter, the ratio of long- to short-axis diameter, and signal intensity on each sequence; new criteria such as the margin (smooth, lobulated, spiculated, indistinct), a homogenous or mottled heterogeneous appearance, gross enhancement and its pattern, the venous encasement, and the dirty perirectal fat signal. RESULTS: Among 75 patients, 22 (29%) were node-positive. All patients who did not have detectable LN on MR were node-free (n = 15). Presence of LNs > 4 mm was significantly higher in the node-positive group. Presence of LNs > 8 mm was seen only in the node-positive group. Presence of a spiculated border and an indistinct border shows sensitivities of 45 and 36%, and specificities of 100 and 100%, respectively. Presence of a mottled heterogeneic pattern shows a sensitivity of 50%, a specificity of 95%. The presence of these three features were strongly correlated with LN positivity (P < 0.001, respectively). Presence of a venous encasement (n = 4) and dirty perirectal fat signal (n = 3) were also significantly (P < 0.05, respectively) correlated with LN positivity. CONCLUSION: In addition to size, new criteria such as a spiculated or indistinct border and a mottled heterogeneous appearance could be useful to predict regional lymph node involvement in patients with rectal cancer.     

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.     

What are the necessary corrections for dynamic cardiac SPECT?

Journal of Nuclear Cardiology -     

Simultaneous PET–MR acquisition and MR-derived motion fields for correction of non-rigid motion in PET

Objective  

Positron emission tomography (PET) provides an accurate measurement of radiotracer concentration in vivo, but performance can be limited by subject motion which degrades spatial resolution and quantitative accuracy. This effect may become a limiting factor for PET studies in the body as PET scanner technology improves. In this work, we propose a new approach to address this problem by employing motion information from images measured simultaneously using a magnetic resonance (MR) scanner.     

Life-threatening versus non-life-threatening manual strangulation: are there appropriate criteria for MR imaging of the neck?

The aim of the study was to determine objective radiological signs of danger to life in survivors of manual strangulation and to establish a radiological scoring system for the differentiation between life-threatening and non-life-threatening strangulation by dividing the cross section of the neck into three zones (superficial, middle and deep zone). Forensic pathologists classified 56 survivors of strangulation into life-threatening and non-life-threatening cases by history and clinical examination alone, and two blinded radiologists evaluated the MRIs of the neck. In 15 cases, strangulation was life-threatening (27%), compared with 41 cases in which strangulation was non-life-threatening (73%). The best radiological signs on MRI to differentiate between the two groups were intramuscular haemorrhage/oedema, swelling of platysma and intracutaneous bleeding (all p = 0.02) followed by subcutaneous bleeding (p = 0.034) and haemorrhagic lymph nodes (p = 0.04), all indicating life-threatening strangulation. The radiological scoring system showed a sensitivity and specificity of ≈70% for life-threatening strangulation, when at least two neck zones were affected. MRI is not only helpful in assessing the severity of strangulation, but is also an excellent documentation tool that is even admissible in court.     

Is there a threshold intensity for aerobic training in cardiac patients?

PURPOSE: Recent guidelines have recommended the use of a percentage of oxygen uptake reserve (VO2R) for prescribing aerobic exercise intensity for cardiac patients. Moreover, these guidelines suggest that a threshold intensity may exist, below which no improvement in peak oxygen uptake (VO2peak) occurs. The purpose, therefore, was to translate the intensity of aerobic exercise in previous training studies using cardiac patients into %VO2R units, and determine whether a threshold intensity exists. METHODS: Twenty-three studies, using 28 groups of aerobically trained cardiac patients, were identified in which VO2peak was measured before and after training by gas exchange. Intensity of exercise was variously described as a percentage of VO2peak, percentage of peak heart rate (HRpeak), percentage of heart rate reserve (HRR), or percentage of peak workload. These intensities were translated into equivalent units of %VO2R. RESULTS: Of the 28 groups of patients, three failed to show significant improvements in VO2peak. These groups exercised at intensities corresponding to 47-55% of VO2R. However, six other groups exercised at comparable intensities (i.e., 42% to 55% of VO2R) and experienced significant increases in VO2peak. Other confounding variables in these studies were similar, including the initial VO2peak of the subjects, suggesting that the failure of three groups to significantly improve aerobic capacity was due to their small sample size. CONCLUSION: No threshold intensity for aerobic training was identified in cardiac patients, with the lowest intensity studied being approximately 45% of VO2R. It is possible that intensities below this value may be an effective training stimulus, especially in extremely deconditioned subjects, but further research is needed to test that possibility and to determine whether a threshold exists.     

Breast cancer abutting the pectoralis major muscle on breast MRI: what are the clinical implications?

Objectives:Defining the posterior extent of breast cancer prior to surgery has clinical implications. However, there are limited data available to guide the interpretation of breast cancers seen on MRI that abut the pectoralis muscle but lack associated muscle enhancement.Methods:In this retrospective study of breast MRIs performed between May 2008 and July 2019, 43 female patients demonstrated breast cancers abutting the pectoralis muscle without enhancement of the muscle itself. Imaging features of the cancers as well as pathologic and clinical outcomes were recorded. Statistical analyses of associations between imaging findings and clinical outcomes were performed using Fisher’s exact test, logistic regression, a Mann–Whitney U test and/or Student’s t-test.Results:The pectoralis major muscle was pathologically invaded by carcinoma in 4/43 (9.3%). There was no significant association between pectoralis muscle invasion and any MR imaging feature of the breast cancer. Tumors causing deformation of the muscle contour by MRI, tumors larger in size, tumors with a larger extent abutting the muscle and tumors in which the imaging feature abutting the muscle was a mass or non-mass enhancement (rather than a spicule) were more commonly seen in patients with muscle invasion, although these did not reach statistical significance (p > 0.05).Conclusion:In this study, a lack of pectoralis muscle enhancement by MRI did not exclude pathologic muscle invasion by breast cancers abutting the muscle.Advances in knowledge:Knowledge of the likelihood of pectoralis muscle involvement for breast cancers abutting the pectoralis muscle on MRI may guide accurate interpretation and definition of the posterior extent of disease.     

Is there a role for CT in the neonate?

Choice of imaging modalities should be based on scientific proof and best practice guidelines. However, in the neonatal age group there is a paucity of medical evidence, and imaging is often guided by local experience, availability of equipment and expertise, and by logistical factors. This paper discusses possible indications for CT in the neonate, the associated radiation protection issues, common CT findings and potential pitfalls in technique and image interpretation. Due to the particular range of abnormalities in this age group, imaging must be tailored to the individual, and should in most cases be done in specialist units.     

What are the basic concepts of temporal, contrast, and spatial resolution in cardiac CT?

An imaging instrument can be characterized by its spatial resolution, contrast resolution, and temporal resolution. The capabilities of computed tomography (CT) relative to other cardiac imaging modalities can be understood in these terms. The purpose of this review is to characterize the spatial, contrast, and temporal resolutions of cardiac CT in practical terms.     

Life-span exposure to sinusoidal-50 Hz magnetic field and acute low-dose γ radiation induce carcinogenic effects in Sprague-Dawley rats

Background In 2002 the International Agency for Research on Cancer classified extremely low frequency magnetic fields (ELFMF) as a possible carcinogen on the basis of epidemiological evidence. Experimental bioassays on rats and mice performed up to now on ELFMF alone or in association with known carcinogens have failed to provide conclusive confirmation.

Objectives To study the carcinogenic effects of combined exposure to sinusoidal-50?Hz (S-50Hz) magnetic fields and acute γ radiation in Sprague-Dawley rats.

Methods We studied groups of male and female Sprague-Dawley rats exposed from prenatal life until natural death to 20 or 1000?μT S-50Hz MF and also to 0.1?Gy γ radiation delivered as a single acute exposure at 6 weeks of age.

Results The results of the study showed significant carcinogenic effects for the mammary gland in males and females and a significant increased incidence of malignant schwannomas of the heart as well as increased incidence of lymphomas/leukemias in males.

Conclusions These results call for a re-evaluation of the safety of non-ionizing radiation.     

When are breast cancer patients old enough for the quitclaim of local control?

Background

Although postoperative radiotherapy (RT) after breast-conserving surgery (BCS) halves the 10-year recurrence rate in breast cancer patients through all age groups, the question of whether RT may be omitted and replaced by endocrine therapy for women aged 70?years and older with low-risk factors has recently become an issue of debate.

Methods

Survey of the relevant recent literature (Medline) and international guidelines.

Results

Three randomized studies investigating the effect of RT in older women revealed significantly increased local recurrence rates when RT was omitted, and a negative impact on disease-free survival was observed in two of these trials. Despite these findings, in one of the studies omission of RT in women over 70 is recommended, leading to a respective amendment in the guidelines of the American National Comprehensive Cancer Network. Several large retrospective cohort studies analyzing the outcome of patients over 65?years with and without RT have since been published and showed a significantly improved local control in all subgroups of advanced age and stage, which predominantly translated into improved disease-free and overall survival.

Conclusion

No subgroup of elderly patients has yet been identified that did not profit from RT in terms of local control. Therefore, chronological age alone is not an appropriate criterion for deciding against or in favor of adjuvant RT. The DEGRO breast cancer expert panel explicitly discourages determination of a certain age for the omission of postoperative RT in healthy elderly women with low-risk breast cancer. For frail elderly women, treatment decisions should be individually decided on the basis of standardized geriatric assessment.     

Diagnostic potential of ultrafast contrast-enhanced MRI of the breast in hypervascularized lesions: are there advantages in comparison with standard dynamic MRI?

PURPOSE: Our goal was to evaluate possible diagnostic advantages of ultrafast MRI of the breast in comparison with dynamic MRI. METHOD: Thirty patients with 35 hypervascularized lesions were selected prospectively after undergoing standard dynamic MRI (temporal resolution 87 s). Patients underwent additional ultrafast imaging (temporal resolution 2 s). Onset, rate, and pattern of enhancement were analyzed. RESULTS: Histopathology revealed 15 malignant and 20 benign lesions (3-40 mm). Enhancement pattern was centripetal in 2 benign and 4 malignant lesions, centrifugal in 5 and 3, and homogeneous in 13 and 8. The onset of lesion enhancement ranged from 3 to 13 s (parenchymal enhancement 4-14 s) and the rate of enhancement from 3 to 70%/s, both without any correlation to the histologic diagnosis. There was no significant difference between ultrafast and standard dynamic MRI. CONCLUSION: Ultrafast MRI does not provide additional information in comparison with standard dynamic MRI.     

Fogging on T2-weighted MR after acute ischaemic stroke: how often might this occur and what are the implications?

Fogging is the temporary loss of visibility of an infarct on CT which occurs in the subacute phase at about 2 weeks after stroke. It occurs in up to 40% of medium to large infarcts on CT. It is unclear whether or how often fogging occurs on T2-weighted MR, but if it does occur, it can cause underestimation of true infarct size. This study examined the possible frequency and time scale of fogging on T2-weighted MR. We conducted a blinded, independent review of prospectively collected MR scans from patients with symptoms of cortical ischaemic stroke, scanned sequentially up to 7 weeks after stroke. On each scan maximum infarct area was measured, and the infarct extent and swelling were coded on a validated scale. Fogging was suggested by reduced infarct extent between initial and subsequent scans. In 30 patients (with 74 scans) there was some apparent fogging in 50% of patients between 6 and 36 days (median 10 days) after stroke. Reduction in infarct extent on T2-weighted MR which may be attributed to fogging occurs in a significant proportion of patients with cortical infarcts. This may lead to an underestimation of true final infarct extent. This suggests that true infarct extent on T2-weighted MR can probably only be assessed on scans obtained beyond 7 weeks after stroke.