Peter Aspelin

Dynamic MR imaging of the breast. Analysis of kinetic and morphologic diagnostic criteria.

Purpose: To assess the value of kinetic and architectural diagnostic criteria on dynamic MR breast imaging, and to construct a scoring system for lesion characterization. Material and Methods: A total of 92 women with 109 histopathologically verified breast lesions were included in this retrospective study. The patients were examined by a 1.5 T system using a dedicated double breast coil. A dynamic examination with one precontrast and seven postcontrast series was performed, using a T1-weighted 3D FLASH sequence. Thirty lesions (15 malignant and 15 benign) were randomly chosen for the validation set, and the remaining 79 lesions (62 malignant and 17 benign) formed the estimation set, in which multivariate analysis was performed in order to select the most important features. These parameters were then used for constructing the scoring system, which was tested on the validation set. The scoring system was compared with the routine standard evaluation that used all established diagnostic criteria. ROC curves were generated to assess the diagnostic accuracy of different approaches. Results: In the multivariate analysis of the 79 lesions, time-to-peak enhancement and the descriptor of margins were found to be the most important independent factors for distinguishing benign from malignant lesions, and formed the basis of the scoring system. The areas under the ROC curves for the standard evaluation, and the scoring system were 0.813 and 0.880 in the 30 lesions. Conclusion: Time-to-peak enhancement and the descriptor of margins appear to be the most important diagnostic criteria for mass lesions in dynamic breast MR imaging.

Eccentric Training of the Gastrocnemius-Soleus Complex in Chronic Achilles Tendinopathy Results in Decreased Tendon Volume and Intratendinous Signal as Evaluated by MRI

Background Satisfactory treatment results have been reported after eccentric calf muscle strength training in patients with chronic Achilles tendinopathy. Hypothesis Magnetic resonance imaging may be a useful adjunct in the evaluation of the effect of 3 months of eccentric calf muscle strength training. Study Design Prospective cohort study. Methods Using magnetic resonance imaging, the Achilles tendons were investigated in 25 patients (16 men and 9 women) ranging in age from 28 to 70 years (median, 51 years) before and after training. Five different magnetic resonance imaging sequences were used. Tendon volume and mean intratendinous signal were calculated using a new seed-growing technique showing 99.3% and 96.6% intraobserver reliability, respectively. The clinical outcome was categorized according to pain level and performance using a questionnaire completed by the patient. Results The eccentric training resulted in a 14% (mean) decrease of tendon volume measured on T1-weighted images, from 6.6 ± 3.1 cm3 to 5.8 ± 2.3 cm3 (P < .05). The intratendinous signal in the symptomatic Achilles tendon measured on proton density-weighted images decreased 23% (mean), from 227 ± 77 signal units to 170 ± 83 signal units (P < .05). The gadolinium contrast agent-enhanced images did not add further value compared with other sequences. Clinical Outcome The clinical outcome was categorized as excellent in 10, good in 3, fair in 5, and poor in 8 patients. The [. Delta]signal correlated significantly with the pain level (P < .05). Conclusions Eccentric training resulted in decreased tendon volume and intratendinous signal and was correlated with an improved clinical outcome. Magnetic resonance imaging techniques can be used as an adjunct to clinical evaluation by monitoring morphologic effects in clinical treatment studies of Achilles tendinopathy.

Contrast medium extravasation injury: guidelines for prevention and management.

Abstract. Extravasation of contrast material is a well-recognized complication of contrast-enhanced imaging studies. The management of this complication is contentious; therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and issue guidelines. A comprehensive literature search was carried out. The resulting report was discussed at the 8th European Symposium on Urogenital Radiology in Genoa, Italy. Automated power injection may result in extravasation of large volumes and may or can lead to severe tissue damage. Infants, young children and unconscious and debilitated patients are particularly at risk of extravasation during contrast media injection. Fortunately, most extravasations result in minimal swelling or erythema, with no long-term sequelae; however, severe skin necrosis and ulceration may occur. Large volumes of high osmolar contrast media are known to induce significant tissue damage. Compartment syndrome may be seen associated with extravasation of large volumes. Conservative management is often adequate, but in serious cases the advice of a plastic surgeon is recommended. Based on the review simple guidelines for prophylaxis and management of contrast medium extravasation injuries are proposed.

Poor reproducibility of classification of proximal humeral fractures Additional CT of minor value

Fractures of the proximal humerus can be described using the Neer and AO fracture classifications. To assess the reproducibility and reliability of these classifications, we investigated 26 proximal humeral fractures with both plain radiographs and CT. 5 specialists in orthopedic surgery and 5 specialists in radiology independently classified all radiographs on 2 occasions. There was a moderate agreement between the observers when using the Neer classification, but only a fair agreement with the AO classification. The Neer system had a kappa value of 0.42 and the AO had a value of 0.31 in the first assessment. In the second assessment the kappa values were 0.45 and 0.30, respectively. Intraobserver reproducibility was slight to almost perfect agreement with Neer (kappa range 0.20-0.85) and slight to moderate agreement with AO (kappa range 0.16-0.60). The observers most familiar with shoulder fracture radiographs and shoulder fracture treatment were more consistent in their classifications. We conclude that even with CT, the fracture classifications of Neer and AO have a low consistency. Neither classification system is reproducible enough to allow comparisons of different studies.

Intratendinous Alterations as Imaged by Ultrasound and Contrast Medium-Enhanced Magnetic Resonance in Chronic Achillodynia

Objectives: We performed a comparative study of ultrasonography and gadolinium imaging contrast-enhanced T1-weighted magnetic resonance to evaluate tendon pathology in chronic Achilles tendon disorder. Another main issue was to evaluate the structural basis as defined by histopathology from hypoechoic compared with normoechic areas within the same tendon. Materials and Methods: Twenty patients (16 male, 4 females, median age 40 years) with chronic achillodynia participated in the study. Clinical examination revealed swelling and tenderness localized to the midportion of the Achilles tendon. Contrast medium-enhanced magnetic resonance imaging (CME-MRI) was performed in all patients. Ultrasonography-guided core biopsies were taken from regions with a clear widening of the tendon and a pathologic low-echo signal as well as from normoechoic areas. The specimens were analyzed with a standardized protocol giving a total tendon score (0–24), and a stereologic method for quantification of glycosaminoglycan (GAG)-rich areas. Results: The volume of the intratendinous abnormality was larger in 13 of 20 when imaged by CME-MR (P < 0.05), whereas the shape and enlargement of the tendon per se were similarly imaged by ultrasound (US) and CME-MR. Tendon pathology as imaged by US was graded as severe from hypoechoic regions and moderate from normoechoic regions. The corresponding quantification of GAGs was 0.36 compared with 0.17, respectively (P < 0.001). Conclusion: CME-MR imaging revealed greater sensitivity in demonstrating intratendinous pathology than the ultrasound; this was documented by the larger size of the corresponding lesion and the fact that the pathology was occurring in areas that were considered normal by ultrasonography. US hypoechoic areas showed a markedly abnormal tendon structure including an increased amount of GAG-rich areas. However, moderate pathology was also found in the neighboring normoechogenous areas within the same tendon, indicating a more generalized disorder than depicted by echogenic properties.

Contrast-Medium-Induced Nephropathy Correlated to the Ratio Between Dose in Gram Iodine and Estimated GFR in ml/min

Purpose: To suggest a more precise tool when assessing the risk of contrast-medium-induced nephropathy (CIN), i.e. the ratio between contrast medium (CM) dose expressed in grams of iodine (g-I) and estimated glomerular filtration rate in ml/min (eGFR; based on equations using serum-creatinine (s-Cr), weight, height, age, and/or sex), here named I-dose/GFR ratio. Material and Methods: A Medline search of published CIN investigations reporting mean eGFR and mean dose of low-osmolality CM (LOCM) identified 10 randomized controlled prophylactic and 2 cohort coronary investigations, and 3 randomized and 1 cohort computed tomographic (CT) investigation. From the randomized trials, data were collected only from the placebo or control arms, unless there was no significant difference between the control and test groups. The mean I-dose/GFR ratio of each study was correlated with the mean frequency of CIN-1 (s-Cr rise⩾44.2 µmol/l or ⩾20–25%) and CIN-2 (oliguria or requiring dialysis). A maximum dose according to an I-dose/GFR ratio = 1 in patients with s-Cr ranging from 100 to 300 µmol/l was compared with that of Cigarroas formula and with a “European consensus” threshold published by the European Society of Urogenital Radiology, both using s-Cr alone to predict renal function. McCulloughs formula was used to assess the risk of CIN requiring dialysis at an I-dose/GFR ratio = 1 with LOCM. Results: The coronary investigations revealed a linear correlation with a correlation coefficient between the I-dose/GFR ratio and the frequency of CIN-1 and CIN-2 of 0.91 (P<0.001) and 0.84 (P = 0.001), respectively. At a mean I-dose/GFR ratio = 1, the regression line indicated a 10% risk of CIN-1 and a 1% risk of CIN-2. At a mean I-dose/GFR ratio = 3, the risk of CIN-1 and CIN-2 increased to about 50% and 15%, respectively. Pooled weighted data from the CT investigations revealed a 12% risk of CIN-1 at a mean I-dose/GFR ratio = 1.1 and no cases of CIN-2. The maximum CM dose according to an I-dose/GFR ratio = 1 was about 30–50% of that of both Cigarroas formula and the “European consensus” in elderly low-weight individuals, while it was similar for middle-aged individuals weighing about 90 kg. McCulloughs formula suggests that there will be an exponentially increasing risk of CIN requiring dialysis, but at an I-dose/GFR ratio = 1 and using LOCM it will not exceed 1% until GFR decreases below 30 ml/min in diabetics and below 20 ml/min in non-diabetics. Conclusion: Using the I-dose/GFR ratio may be a more expedient way of improving risk assessment of CIN than todays common practice of estimating CM dose from volume alone and renal function from s-Cr alone. Prospective studies based on individual patient data are encouraged to define the risk of CIN at various I-dose/GFR ratios and correlated to type of CM, examination, risk factors, etc.

Contrast Medium Dose-to-GFR Ratio: A Measure of Systemic Exposure to Predict Contrast-Induced Nephropathy after Percutaneous Coronary Intervention

Background: The contrast medium (CM) dose-to-eGFR (estimated glomerular filtration rate) ratio has recently been advocated to express systemic exposure to CM in assessing the risk of contrast medium-induced nephropathy (CIN). Purpose: To evaluate how CIN risk might vary with decreasing eGFR at fixed CM-dose/eGFR ratios and other CIN risk factors, and to find a relatively safe CM-dose/eGFR ratio. Material and Methods: 391 patients underwent primary coronary angioplasty for ST-segment elevation acute myocardial infarction. CM dose (grams iodine; g I), eGFR (ml/min), and preprocedural CIN risk factors were entered into a multiple logistic regression model. From the established statistical model, the probability of CIN (≥44.2 µmol/l serum creatinine rise or oliguria/anuria) was calculated at various eGFR levels based on g-I/eGFR ratios of 1:2, 1:1, 2:1, and 3:1. Results: At a g-I/eGFR ratio <1 the risk of CIN was 3%, while it was 25% at a g-I/eGFR ratio ≥1. Independent predictors of CIN were CM dose, eGFR, left ventricular ejection fraction (LVEF) and cardiogenic shock (ROC area =0.87). An estimated CIN risk of 10% would for example occur at a g-I/eGFR ratio of 1.5:1 in patients with 50% LVEF without shock. At a 1:2, 1:1, 2:1, and 3:1 g-I/eGFR ratio with 50% LVEF without shock, the CIN risk was about 2, 6, 18, and 30%, respectively, over a wide range of eGFR values (30–90 ml/min). At a 1:1 g-I/eGFR ratio with 50% LVEF+shock, 25% LVEF without shock, or 25% LVEF+shock, the CIN risk was 20, 55, and 80%, respectively. Conclusion: Relating CM dose to eGFR appears to be an attractive pharmacotoxic model to assess CIN risk. At fixed CM-dose/eGFR ratios, CIN risk increased marginally with decreasing eGFR. Limiting the CM dose in g I numerically to the eGFR value in ml/min or less may be relatively safe with regard to CIN, unless multiple risk factors are present.

Radiologically isolated syndrome--incidental magnetic resonance imaging findings suggestive of multiple sclerosis, a systematic review.

With increasing availability of magnetic resonance imaging (MRI), there is also an increase in incidental abnormal findings. MRI findings suggestive of multiple sclerosis in persons without typical multiple sclerosis symptoms and with normal neurological findings are defined as radiologically isolated syndrome (RIS). Half of the persons with RIS have their initial MRI because of headache, and some have a subclinical cognitive impairment similar to that seen in multiple sclerosis. Radiological measurements also show a similarity between RIS and multiple sclerosis. Approximately two-thirds of persons with RIS show radiological progression and one-third develop neurological symptoms during mean follow-up times of up to five years. Cervical cord lesions are important predictors of clinical conversion. Management has to be individualised, but initiation of disease modifying therapy is controversial and not recommended outside of clinical trials since its effects have not been studied in RIS. Future studies should try to establish the prevalence and long-term prognosis of RIS, its impact on quality of life, and define the role of disease modifying therapy in RIS.

Sensitivity and specificity of MR mammography with histopathological correlation in 250 breasts.

Purpose: The aim of our prospective study was to determine the diagnostic accuracy of MR mammography (MRM) in detecting malignant disease. Material and Methods: In 231 consecutive patients scheduled for surgery because of mammographic or palpable lesions suspected of malignancy, the breasts were examined with T1-weighted transversal images using a 3-D fast low angle shot (FLASH) sequence. One pre- and 2 post-contrast images were obtained. Histological examination of the surgical specimens showed carcinoma in 155 breasts, of which 138 were invasive and 17 in situ. Results: MRM detected 144 of the 155 malignancies and was false-negative in 11 cases. Eight of these MRM-missed tumours were invasive and 3 were in situ cancers. Benign lesions were found at microscopy in 95 breasts, of which MRM correctly diagnosed 69. The cellular composition of the 26 false-positive lesions (myxomatous stromal change, high vascularity, and epithelial or apocrine hyperplasia) might explain the false positivity. The sensitivity and specificity of MRM were 93% and 73%, respectively. Conclusion: MRM should be interpreted with caution, and supplemented with e.g. mammography and ultrasonography.

3D-radiographic analysis does not improve the Neer and AO classifications of proximal humeral fractures.

The Neer and AO fracture classifications for fractures of the proximal humerus have shown poor reproducibility based on plain radiography. We wanted to investigate whether the addition of 3-dimensional (3D) reconstructions would increase the reproducibility of classification. 7 observers independently classified 24 fractures of the proximal humerus using both plain radiographs, CT and 3D and the classification was repeated 2 months later. There was a moderate interobserver agreement when using the Neer classification, but only a fair agreement with the AO classification. The Neer system had a mean kappa value of 0.44 and the AO had a value of 0.32 for the first assessment. In the second assessment, the mean kappa values were 0.49 and 0.34, respectively. Intraobserver reproducibility was fair to substantial agreement for Neer (kappa range 0.27-0.73) and for AO (kappa range 0.29-0.74). In conclusion, the addition of CT and 3D to plain radiographs did not improve the reproducibility of the classifications of Neer and AO of the proximal humerus.