A retrospective external validation study of the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) for the management of solitary central cartilage tumours of the proximal humerus and around the knee

OBJECTIVES

This study aimed to externally validate the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) recommendations for differentiation/follow-up of central cartilage tumours (CCTs) of the proximal humerus, distal femur, and proximal tibia and to propose BACTIP adaptations if the results provide new insights.

METHODS

MRIs of 123 patients (45 ± 11 years, 37 men) with an untreated CCT with MRI follow-up (n = 62) or histopathological confirmation (n = 61) were retrospectively/consecutively included and categorised following the BACTIP (2003-2020 / Ghent University Hospital/Belgium). Tumour length and endosteal scalloping differences between enchondroma, atypical cartilaginous tumour (ACT), and high-grade chondrosarcoma (CS II/III/dedifferentiated) were evaluated. ROC-curve analysis for differentiating benign from malignant CCTs and for evaluating the BACTIP was performed.

RESULTS

For lesion length and endosteal scalloping, ROC-AUCs were poor and fair-excellent, respectively, for differentiating different CCT groups (0.59-0.69 versus 0.73-0.91). The diagnostic performance of endosteal scalloping and the BACTIP was higher than that of lesion length. A 1° endosteal scalloping cut-off differentiated enchondroma from ACT + high-grade chondrosarcoma with a sensitivity of 90%, reducing the potential diagnostic delay. However, the specificity was 29%, inducing overmedicalisation (excessive follow-up). ROC-AUC of the BACTIP was poor for differentiating enchondroma from ACT (ROC-AUC = 0.69; 95%CI = 0.51-0.87; p = 0.041) and fair-good for differentiation between other CCT groups (ROC-AUC = 0.72-0.81). BACTIP recommendations were incorrect/unsafe in five ACTs and one CSII, potentially inducing diagnostic delay. Eleven enchondromas received unnecessary referrals/follow-up.

CONCLUSION

Although promising as a useful tool for management/follow-up of CCTs of the proximal humerus, distal femur, and proximal tibia, five ACTs and one chondrosarcoma grade II were discharged, potentially inducing diagnostic delay, which could be reduced by adapting BACTIP cut-off values.

CLINICAL RELEVANCE STATEMENT

Mostly, Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) assesses central cartilage tumours of the proximal humerus and the knee correctly. Both when using the BACTIP and when adapting cut-offs, caution should be taken for the trade-off between underdiagnosis/potential diagnostic delay in chondrosarcomas and overmedicalisation in enchondromas.

KEY POINTS

• This retrospective external validation confirms the Birmingham Atypical Cartilage Tumour Imaging Protocol as a useful tool for initial assessment and follow-up recommendation of central cartilage tumours in the proximal humerus and around the knee in the majority of cases. • Using only the Birmingham Atypical Cartilage Tumour Imaging Protocol, both atypical cartilaginous tumours and high-grade chondrosarcomas (grade II, grade III, and dedifferentiated chondrosarcomas) can be misdiagnosed, excluding them from specialist referral and further follow-up, thus creating a potential risk of delayed diagnosis and worse prognosis. • Adapted cut-offs to maximise detection of atypical cartilaginous tumours and high-grade chondrosarcomas, minimise underdiagnosis and reduce potential diagnostic delay in malignant tumours but increase unnecessary referral and follow-up of benign tumours.

Evaluation of response to neoadjuvant chemotherapy in osteosarcoma using dynamic contrast-enhanced MRI: development and external validation of a model

OBJECTIVE

To identify which dynamic contrast-enhanced (DCE-)MRI features best predict histological response to neoadjuvant chemotherapy in patients with an osteosarcoma.

METHODS

Patients with osteosarcoma who underwent DCE-MRI before and after neoadjuvant chemotherapy prior to resection were retrospectively included at two different centers. Data from the center with the larger cohort (training cohort) was used to identify which method for region-of-interest selection (whole slab or focal area method) and which change in DCE-MRI features (time to enhancement, wash-in rate, maximum relative enhancement and area under the curve) gave the most accurate prediction of histological response. Models were created using logistic regression and cross-validated. The most accurate model was then externally validated using data from the other center (test cohort).

RESULTS

Fifty-five (27 poor response) and 30 (19 poor response) patients were included in training and test cohorts, respectively. Intraclass correlation coefficient of relative DCE-MRI features ranged 0.81-0.97 with the whole slab and 0.57-0.85 with the focal area segmentation method. Poor histological response was best predicted with the whole slab segmentation method using a single feature threshold, relative wash-in rate <2.3. Mean accuracy was 0.85 (95%CI: 0.75-0.95), and area under the receiver operating characteristic curve (AUC-index) was 0.93 (95%CI: 0.86-1.00). In external validation, accuracy and AUC-index were 0.80 and 0.80.

CONCLUSION

In this study, a relative wash-in rate of <2.3 determined with the whole slab segmentation method predicted histological response to neoadjuvant chemotherapy in osteosarcoma. Consistent performance was observed in an external test cohort.

Pediatric Imaging of the Elbow: A Pictorial Review

The elbow is a complex joint, subject to a wide range of traumatic, inflammatory, metabolic and neoplastic insults. The pediatric elbow has several diagnostic pitfalls due to the normal developmental changes in children. Knowledge of these normal variants is essential for both diagnosis and management of their elbow injuries. Radiography remains the first imaging modality of choice. Magnetic resonance imaging is excellent in evaluating lesions within the bone and soft tissues. In this pictorial essay, we provide insights into pediatric elbow imaging, show a range of entities specific to the pediatric elbow, and discuss diagnostic pitfalls that result from normal elbow growth in children.

Magnetic resonance imaging for forensic age estimation in living children and young adults: a systematic review

The use of MRI in forensic age estimation has been explored extensively during the last decade. The authors of this paper synthesized the available MRI data for forensic age estimation in living children and young adults to provide a comprehensive overview that can guide age estimation practice and future research. To do so, the authors searched MEDLINE, Embase and Web of Science, along with cited and citing articles and study registers. Two authors independently selected articles, conducted data extraction, and assessed risk of bias. They considered study populations including living subjects up to 30 years old. Fifty-five studies were included in qualitative analysis and 33 in quantitative analysis. Most studies had biases including use of relatively small European (Caucasian) populations, varying MR approaches and varying staging techniques. Therefore, it was not appropriate to pool the age distribution data. The authors found that reproducibility of staging was remarkably lower in clavicles than in any other anatomical structure. Age estimation performance was in line with the gold standard, radiography, with mean absolute errors ranging from 0.85 years to 2.0 years. The proportion of correctly classified minors ranged from 65% to 91%. Multifactorial age estimation performed better than that based on a single anatomical site. The authors found that more multifactorial age estimation studies are necessary, together with studies testing whether the MRI data can safely be pooled. The current review results can guide future studies, help medical professionals to decide on the preferred approach for specific cases, and help judicial professionals to interpret the evidential value of age estimation results.

Forensic age estimation based on development of third molars: a staging technique for magnetic resonance imaging

BACKGROUND

The development of third molars can be evaluated with medical imaging to estimate age in subadults. The appearance of third molars on magnetic resonance imaging (MRI) differs greatly from that on radiographs. Therefore a specific staging technique is necessary to classify third molar development on MRI and to apply it for age estimation.

AIM

To develop a specific staging technique to register third molar development on MRI and to evaluate its performance for age estimation in subadults.

MATERIALS AND METHODS

Using 3T MRI in three planes, all third molars were evaluated in 309 healthy Caucasian participants from 14 to 26 years old. According to the appearance of the developing third molars on MRI, descriptive criteria and schematic representations were established to define a specific staging technique. Two observers, with different levels of experience, staged all third molars independently with the developed technique. Intra- and inter-observer agreement were calculated. The data were imported in a Bayesian model for age estimation as described by Fieuws et al. (2016). This approach adequately handles correlation between age indicators and missing age indicators. It was used to calculate a point estimate and a prediction interval of the estimated age. Observed age minus predicted age was calculated, reflecting the error of the estimate.

RESULTS

One-hundred and sixty-six third molars were agenetic. Five percent (51/1096) of upper third molars and 7% (70/1044) of lower third molars were not assessable. Kappa for inter-observer agreement ranged from 0.76 to 0.80. For intra-observer agreement kappa ranged from 0.80 to 0.89. However, two stage differences between observers or between staging sessions occurred in up to 2.2% (20/899) of assessments, probably due to a learning effect. Using the Bayesian model for age estimation, a mean absolute error of 2.0 years in females and 1.7 years in males was obtained. Root mean squared error equalled 2.38 years and 2.06 years respectively. The performance to discern minors from adults was better for males than for females, with specificities of 96% and 73% respectively.

CONCLUSION

Age estimations based on the proposed staging method for third molars on MRI showed comparable reproducibility and performance as the established methods based on radiographs.

MRI in multiple myeloma: a pictorial review of diagnostic and post-treatment findings

Magnetic resonance imaging (MRI) is increasingly being used in the diagnostic work-up of patients with multiple myeloma. Since 2014, MRI findings are included in the new diagnostic criteria proposed by the International Myeloma Working Group. Patients with smouldering myeloma presenting with more than one unequivocal focal lesion in the bone marrow on MRI are considered having symptomatic myeloma requiring treatment, regardless of the presence of lytic bone lesions. However, bone marrow evaluation with MRI offers more than only morphological information regarding the detection of focal lesions in patients with MM. The overall performance of MRI is enhanced by applying dynamic contrast-enhanced MRI and diffusion weighted imaging sequences, providing additional functional information on bone marrow vascularization and cellularity.

This pictorial review provides an overview of the most important imaging findings in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma, by performing a ‘total’ MRI investigation with implications for the diagnosis, staging and response assessment.

Main message

• Conventional MRI diagnoses multiple myeloma by assessing the infiltration pattern.

• Dynamic contrast-enhanced MRI diagnoses multiple myeloma by assessing vascularization and perfusion.

• Diffusion weighted imaging evaluates bone marrow composition and cellularity in multiple myeloma.

• Combined morphological and functional MRI provides optimal bone marrow assessment for staging.

• Combined morphological and functional MRI is of considerable value in treatment follow-up.

The diagnostic value of SE MRI and DWI of the spine in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma

OBJECTIVES

To evaluate DWI of the bone marrow in the differentiation of monoclonal gammopathy of undetermined significance (MGUS), smouldering myeloma (SMM) and multiple myeloma (MM).

METHODS

The retrospective study includes 64 patients with MGUS, 27 with SMM, 64 with new MM and 12 controls. Signal intensity (SI) of spinal SE-MRI and DWI (b0-1000) as well as apparent diffusion coefficients (ADC) were measured in the T10 and L3. Qualitative assessment of b-images was performed by one experienced radiologist.

RESULTS

ADC600 and ADC1000 are the best ADC values in differentiating patient groups (p < 0.030). SIT2, SIb1000 and ADC1000 are higher and SIT1 lower in L3 compared to T10 (p < 0.050). All quantitative parameters of L3 can differentiate significantly between MGUS and MM (p < 0.050) and between patients with percentage plasma cells (PC%) between 0-10 % compared to >50 % (p = 0.001). Only SIT2 for L3 can differentiate MGUS from SMM (p = 0.044) and PC%0-10 from PC%10-25 (p = 0.033). Qualitative interpretation of b1000 images allows differentiating MM patients from those with MGUS or SMM (p < 0.001).

CONCLUSIONS

Spinal SE-MRI can differentiate among MGUS, SMM, MM and control subjects. DWI based on the SI on b1000 images and ADC values is increased in MM compared to MGUS and SMM. Qualitative assessment of b-images can differentiate MM from MGUS or SMM.

KEY POINTS

• ADC values are higher in patients with MM compared to MGUS • DWI parameters change late in disease evolution • DWI is sensitive but not specific in diagnosing patients with MM • Qualitative DWI assessment is good in detecting myeloma patients.

Value of whole body MRI and dynamic contrast enhanced MRI in the diagnosis, follow-up and evaluation of disease activity and extent in multiple myeloma

PURPOSE

To evaluate the significance of dynamic contrast enhanced MRI (DCE-MRI) and whole body MRI (WB-MRI) in the diagnosis, prognosis and assessment of therapy for patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM).

MATERIALS AND METHODS

The retrospective study includes 219 patients providing 463 WB-MRI and DCE-MRI investigations for the subgroups MGUS (n=70), MM active disease (n=126; this includes 70 patients with new diagnosis of MM, according to the International Staging System (ISS): 41.4% ISS stage I, 20.0% ISS stage II, 7.1% ISS stage III, 31.4% insufficient for staging; and 56 patients with '(re-)active disease': 16.07% relapse, 32.14% progressive disease and 51.79% stable disease) and MM remission (n=23; 60.87% complete remission, 17.39% very good partial remission and 21.74% partial remission). Investigations of patients with hereditary multiple exostoses (n=5), neurofibromatosis (n=7) and healthy persons (n=9) were added as control subjects (n=21). WB-MRI evaluation was done by evaluating thirteen skeletal regions, providing a 'skeletal score'. DCE-MRI images of the spine, were analyzed with regions-of-interest and time-intensity-curves (TIC).

RESULTS

All TIC parameters can significantly differentiate between the predefined subgroups (p<0.001). One hundred days after autologous stem cell transplantation a 75% decrease of the slope wash-in value (p<0.001) can be seen. A cubic regression trend between 'skeletal score' and slope wash-in (adj.R(2)=0.412) could demonstrate a significant increase bone marrow perfusion if MM affects more than 10 skeletal regions (p<0.001), associated with a poorer prognosis (p<0.001).

CONCLUSION

DCE-MRI evaluation of the spine is useful for diagnosis of MM, follow-up after stem cell transplantation and evaluation of disease activity. A combined evaluation with WB-MRI and DCE-MRI provides additional micro-vascular information on the morphologic lesions and could help categorize patients with MM in two different groups to offer useful therapeutic and prognostic advise.

Proceedings of the Joint Meeting RBRS Bone Section and Nederlandse Vereniging Voor Skeletaradiologie, Leiden, The Netherlands, 25.0.3.2011-Part II. Tumors and tumorlike conditions of the calcaneous: the usual and the unusual

The calcaneus is an uncommon site for involvement by tumors or tumorlike conditions of bone, although any lesion may involve the calcaneus. The purpose of this paper is to highlight the imaging features of common and uncommon tumors and tumorlike conditions occurring in the calcaneus. Typical case studies will illustrate the imaging findings on different imaging modalities.

Evolution of femoral condylar ossification at MR imaging: frequency and patient age distribution

PURPOSE

To determine how the magnetic resonance (MR) signal intensity seen with variability in distal femoral epiphyseal ossification in children varies with (a) age, (b) sex, (c) distribution to the medial or lateral condyles, and (d) residual physeal cartilage.

MATERIALS AND METHODS

Ethics committee approval was obtained, and informed patient consent was waived. Two pediatric radiologists retrospectively reviewed the consecutive knee MR imaging studies of 910 children (457 boys, 453 girls; age range, 0.7-16.9 years) for variability in ossification and categorized the variability as preossification center, early ossification center, puzzle piece, incomplete puzzle piece, spiculation, or accessory ossification center. Patient age and sex, ossification variability site, residual physeal cartilage, and associated findings were analyzed. Basic descriptive statistical analysis, Student t tests for comparison of continuous variables, and κ statistics analysis of interobserver agreement were performed where appropriate.

RESULTS

In 202 (22.2%) patients (278 condyles), ossification variability was present. In the 910 patients, early ossification center (n = 172, 18.9%) and spiculated configuration of the secondary ossification center (n = 151, 16.6%) were the most common variants. Preossification center (50 [5.5%] patients), puzzle piece (26 [2.9%] patients), accessory ossification center (nine [1.0%] patients), and incomplete puzzle piece (two [0.2%] patients) were seen less often. Ossification variability was more common in the medial condyles (169 [18.6%] of 910 cases) than in the lateral condyles (109 [12.0%] of 910 cases), nearly always posteriorly located (277 [99.6%] of 278 condyles), and more common in boys (153/457 [33.5%]) than in girls (49/453 [10.8%]). Ossification variability was less common with decreasing residual physeal cartilage. Peak patient age ranges for ossification variability were 2-12 years for boys and 2-10 years for girls.

CONCLUSION

Ossification variability in the femoral condyles is common in children and should not be confused with abnormal processes.

MRI evaluation of a new scaffold-based allogenic chondrocyte implantation for cartilage repair

AIM

The present study was designed to evaluate the implantation of alginate beads containing human mature allogenic chondrocytes for the treatment of symptomatic cartilage defects of the knee. MRI was used for the morphological analysis of cartilage repair. The correlation between MRI findings and clinical outcome was also studied.

METHODS

A biodegradable, alginate-based biocompatible scaffold containing human mature allogenic chondrocytes was used for the treatment of symptomatic chondral and osteochondral lesions in the knee. Twenty-one patients were prospectively evaluated with use of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Visual Analogue Scale (VAS) for pain preoperatively and at 3, 6, 9 and 12 months of follow-up. Of the 21 patients, 12 had consented to follow the postoperative MRI evaluation protocol. MRI data were analyzed based on the original MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) and modified MOCART scoring system. The correlation between the clinical outcome and MRI findings was evaluated.

RESULTS

A statistically significant clinical improvement became apparent after 6 months and patients continued to improve during the 12 months of follow-up. One of the two MRI scoring systems that were used, showed a statistically significant deterioration of the repair tissue at 1 year of follow-up. Twelve months after the operation complete filling or hypertrophy was found in 41.6%. Bone-marrow edema and effusion were seen in 41.7% and 25% of the study patients, respectively. We did not find a consistent correlation between the MRI criteria and the clinical results.

DISCUSSION

The present study confirmed the primary role of MRI in the evaluation of cartilage repair. Two MOCART-based scoring systems were used in a longitudinal fashion and allowed a practical and morphological evaluation of the repair tissue. However, the correlation between clinical outcome and MRI findings was poor. Further validation of these scoring systems is mandatory. The promising short-term clinical outcome of the allogenic chondrocytes/alginate beads implantation was not confirmed by the short-term MRI findings.

Health technology assessment of magnetic resonance imaging of the spine and bone marrow

The high spatial resolution and the lack of ionizing radiation, makes magnetic resonance imaging the method of choice for imaging most spinal pathology, especially if associated with neurological symptoms. However, due to the high sensitivity of MR imaging, careful correlation between imaging findings and clinical findings is important to ensure appropriate treatment. Substituting radiographic evaluations for rapid MRI in the primary care setting may offer little additional benefit to patients. It may even increase the costs of care but the decisions about the use of imaging depend on judgments concerning whether the small observed improvement in outcome justifies additional cost. Because the presence of an abscess is a major factor in deciding between conservative and surgical treatment, MRI plays an essential role in the decision-making process concerning the treatment of spondylodiscitis. MR is also the method of choice for quantitative evaluation of bone marrow in lymphoma patients when a crucial therapeutic decision has to be made or for the qualitative evaluation of the spinal cord if compression is suspected in primary spinal malignancy or metastatic disease.

Imaging of the opacified middle ear

Middle ear opacification on imaging studies performed in a non-traumatic setting mostly reflects chronic inflammatory/infectious disease. In some of these patients an underlying cholesteatoma will be found. High-resolution computed tomography examinations and magnetic resonance imaging are often used in the work-out of the disease. High-resolution computed tomography of the opacified middle ear serves to describe the status of the ossicular chain, and its suspensory apparatus, as well as the status of the tympanic and mastoid wall. When ossicular erosions are visualized, the probability of a present cholesteatoma is about 90%. Whereas high-resolution computed tomography is not able to differentiate cholesteatoma from other types of opacification, magnetic resonance imaging is. The combined use of delayed post-Gd T1-weighted images and non-EPI based DWI seems to be the actual best option on this matter.

Ewing's sarcoma: imaging features

AIM

To define an imaging prototype of Ewing's sarcoma (ES).

MATERIALS AND METHODS

Sixty-four patients with a histopathologically and/or genetically proven diagnosis of ES were analyzed for clinical parameters (age, gender and location), radiographic and CT appearance (distribution, matrix, margins, periosteal reaction, articular extension, cortical reaction and the presence of a pathologic fracture). Size, local extension, signal intensity, degree and pattern of enhancement, and the presence of skip metastases were evaluated on MRI. Distant metastases were recorded on bone scintigraphy and chest CT scan.

RESULTS

Patient's age ranged between 7-67 (mean 17.9). Male/female ratio was 2.4/1. Location in the pelvis was most frequent (31%), followed by the femur (20%) and tibia (11%). Most tumors were mixed lytic-sclerotic (75%), and purely lytic in 25%. Plain films and CT scan showed a spiculated periosteal reaction in 50%. A Codman's triangle was seen in 27%. Articular extension was difficult to assess on radiographs. Cortical permeation and destruction is seen in respectively 31 and 42%, whereas cortical thickening is seen in 20%. Pathologic fracture occurred in 7.8%. MRI showed a large mass, with a soft tissue component of more than 50% in 67%. Degree and pattern of enhancement pattern was variable. Signal intensity on T1- and T2-WI was non-specific. Joint involvement was seen in 23%. Isolated involvement of the soft tissue (extraskeletal ES) was seen in 1.5%. Skip metastases at initial presentation were present at initial presentation in 14% and distant metastases in 22%.

CONCLUSIONS

ES occurs in young patients. On radiographs/CT, 37.5% are located in the axial skeleton and 62.5% in the peripheral skeleton. ES is mostly mixed sclerotic-lytic. A spiculated periosteal reaction is most frequent. The most characteristic finding on MRI is the presence of a large soft tissue mass.

Meniscal allograft transplantation: long-term clinical results with radiological and magnetic resonance imaging correlations

Long-term data on the clinical outcome and the fate of the meniscus allograft after transplantation are scarce. In this study we present the clinical, radiological and MRI outcome of the meniscus graft and the articular cartilage after 42 meniscus allograft transplantations in 41 patients with a minimum follow-up of 10 years. A total of 27 medial and 15 lateral meniscal allografts were transplanted. Eleven of the medial allograft procedures were associated with a high tibial osteotomy. The patients were evaluated clinically at the time of transplantation and at the final follow-up using the modified HSS scoring system. The knee injury and osteoarthritis outcome score (KOOS) was used as an evaluation tool for patient-related outcome at the final follow-up. Joint space width narrowing and Fairbank changes were radiological outcome parameters, which were available for 32 patients. Femoral and tibial cartilage degeneration, graft extrusion and signal intensity were scored on MRI scans obtained in 17 patients approximately 1 year after transplantation and at the final follow-up (>10 years). For statistical analysis the patients were divided into three groups: lateral meniscal allograft (LMT), medial meniscal allograft transplantation with a high tibial osteotomy (MMT+HTO) and without (MMT). The modified HSS score revealed a significant improvement in pain and function at the final follow-up for all groups. Further analysis also revealed that an MMT+HTO procedure resulted in a greater improvement at the final follow-up when compared to MMT. Nonetheless, the KOOS scores obtained at the final follow-up revealed the presence of substantial disability and symptoms, in addition to a reduced quality of life. Radiographical analysis revealed no further joint space narrowing in 13/32 knees (41%). Fairbank changes remained stable in 9/32 knees (28%). MRI analysis showed no progression of cartilage degeneration in 6/17 knees (35%). An increased signal intensity of the allograft was present, as was partial graft extrusion in the majority of patients at the final follow-up. Seven cases had to be converted to a total knee arthroplasty during the follow-up; the overall failure rate was 18%. Long-term results after viable meniscus allograft transplantation are encouraging in terms of pain relief and improvement of function. Despite this significant improvement, substantial disability and symptoms were present in all investigated subgroups. Progression of further cartilage degeneration or joint space narrowing was absent in a considerable number of cases, indicating a potential chondroprotective effect. Level of evidence is therapeutic study, Level IV and retrospective analysis of prospectively collected data.

Interobserver Delineation Variation Using CT versus Combined CT + MRI in Intensity–Modulated Radiotherapy for Prostate Cancer

PURPOSE

To quantify interobserver variation of prostate and seminal vesicle delineations using CT only versus CT + MRI in consensus reading with a radiologist.

MATERIAL AND METHODS

The prostate and seminal vesicles of 13 patients treated with intensity-modulated radiotherapy for prostatic adenocarcinoma were retrospectively delineated by three radiation oncologists on CT only and on CT + MRI in consensus reading with a radiologist. The volumes and margin positions were calculated and intermodality and interobserver variations were assessed for the clinical target volume (CTV), seminal vesicles, prostate and three prostatic subdivisions (apical, middle and basal third).

RESULTS

Using CT + MRI as compared to CT alone, the mean CTV, prostate and seminal vesicle volumes significantly decreased by 6.54%, 5.21% and 10.47%, respectively. More importantly, their standard deviations significantly decreased by 63.06%, 62.65% and 44.83%, respectively. The highest level of variation was found at the prostatic apex, followed by the prostatic base and seminal vesicles.

CONCLUSION

Addition of MRI to CT in consensus reading with a radiologist results in a moderate decrease of the CTV, but an important decrease of the interobserver delineation variation, especially at the prostatic apex.

Magnetic resonance imaging anatomy of the prostate and periprostatic area: a guide for radiotherapists

Magnetic resonance imaging (MRI) offers superb soft tissue contrast on T2-weighted images and allows direct multiplanar image acquisition. It can show the internal prostatic anatomy, prostatic margins, and the extent of prostatic tumors in much more detail than computed tomography (CT) images. The present article reviews some key prostatic and periprostatic radiologic landmarks that can be helpful for the radiotherapist using T2-weighted MRI as an adjunct to CT in treatment planning for prostate cancer.

Magnetic resonance assessment of prostate localization variability in intensity-modulated radiotherapy for prostate cancer

PURPOSE

To measure prostate motion with magnetic resonance imaging (MRI) during a course of intensity-modulated radiotherapy.

METHODS AND MATERIALS

Seven patients with prostate carcinoma were scanned supine on a 1.5-Tesla MRI system with weekly pretreatment and on-treatment HASTE T2-weighted images in 3 orthogonal planes. The bladder and rectal volumes and position of the prostatic midpoint (PMP) and margins relative to the bony pelvis were measured.

RESULTS

All pretreatment positions were at the mean position as computed from the on-treatment scans in each patient. The PMP variability (given as 1 SD) in the anterior-posterior (AP), superior-inferior (SI), and right-left (RL) directions was 2.6, 2.4, and 1.0 mm, respectively. The largest variabilities occurred at the posterior (3.2 mm), superior (2.6 mm), and inferior (2.6 mm) margins. A strong correlation was found between large rectal volume (>95th percentile) and anterior PMP displacement. A weak correlation was found between bladder volume and superior PMP displacement.

CONCLUSIONS

All pretreatment positions were representative of the subsequent on-treatment positions. A clinical target volume (CTV) expansion of 5.3 mm in any direction was sufficient to ascertain a 95% coverage of the CTV within the planning target volume (PTV), provided that a rectal suppository is administered to avoid rectal overdistension and that the patient has a comfortably filled bladder (<300 mL).

Magnetic resonance imaging of cartilage and cartilage repair

Magnetic resonance (MR) imaging of articular cartilage has assumed increased importance because of the prevalence of cartilage injury and degeneration, as well as the development of new surgical and pharmacological techniques to treat damaged cartilage. This article will review relevant aspects of the structure and biochemistry of cartilage that are important for understanding MR imaging of cartilage, describe optimal MR pulse sequences for its evaluation, and review the role of experimental quantitative MR techniques. These MR aspects are applied to clinical scenarios, including traumatic chondral injury, osteoarthritis, inflammatory arthritis, and cartilage repair procedures.

Ruptured tuboovarian abscess causing peritonitis in a postmenopausal woman. A difficult diagnosis on imaging

Pelvic inflammatory disease with tuboovarian abscess is rare in postmenopausal women. Clinical and sonographic findings are usually sufficient to recognize pelvic inflammatory disease in premenopausal women, but in the elderly the disease may easily be overlooked, largely by unexpectedness. Computed tomography can be helpful when the clinical and sonographic findings are complex or equivocal. However, when the level of suspicion is low, it can be very difficult to interpret, especially when complicated with peritonitis, as illustrated in the present case report.

Fast magnetic resonance imaging with contrast for soft tissue sarcoma viability

Because dynamic (fast) contrast-enhanced magnetic resonance imaging with its temporal resolution allows evaluation of contrast kinetics of soft tissue sarcomas, its efficacy for defining viable tumor in these neoplasms was studied for three applications: biopsy localization, chemotherapeutic response, and differentiation between recurrence and inflammation after treatment. After conventional T1-weighted and T2-weighted magnetic resonance sequences to localize the lesion, patients had dynamic contrast-enhanced magnetic resonance imaging with fast and ultrafast sequences and postprocessing techniques (subtraction, time-intensity curves, and parametric color-encoding). In 10 of 40 patients, dynamic imaging more precisely defined the most malignant foci of tumor for biopsy than conventional magnetic resonance imaging. After chemotherapy, dynamic imaging distinguished 11 good responders from 21 poor responders. In followup of 196 patients, dynamic imaging detected 42 early enhancing recurrences and excluded recurrent tumor in six late enhancing pseudotumors. Dynamic imaging can differentiate viable tumor from nonviable tumor and inflammation by showing two temporally different phases of contrast enhancement: an early phase correlative with viable tumor at histologic examination, and a late phase when all tissues enhance simultaneously and may be indistinguishable. By showing tumor viability, dynamic contrast-enhanced magnetic resonance imaging can help define biopsy sites, chemotherapeutic response, and presence or absence of recurrences and therefore affect the initial evaluation, treatment, and followup of patients with soft tissue sarcomas.

Dynamic Contrast-Enhanced MR Imaging for Soft Tissue Sarcomas

Dynamic contrast-enhanced magnetic resonance imaging has recently emerged as an important method for evaluating soft tissue sarcomas for biopsy localization, chemotherapeutic response, and long-term follow-up because of its ability to detect viable tumor. This article presents the basic principles of contrast kinetics in soft tissue sarcomas after bolus injection of contrast agent and discusses the current postprocessing methods (subtraction, first-pass image and time-intensity curves with region of interest, and color-encoded techniques) used to display these dynamic studies. Because of its excellent temporal resolution, dynamic MR imaging can delineate the early uptake of contrast agent in sarcomas within seconds after injection, almost synchronous with arterial enhancement, and thereby differentiate the rapidly enhancing viable tumor from the nonenhancing necrotic tumor and the late enhancing changes after surgery, radiation therapy, and chemotherapy.

Bone and soft tissue tumors: the role of contrast agents for MR imaging

Magnetic resonance imaging is an important modality for the imaging evaluation of musculoskeletal tumors. Although there is general agreement on the value of unenhanced MR in detection, diagnosis and staging, intravenous use of gadolinium-contrast media (gd-CM) is indicated in selected cases. The purpose of this article is to review the basic pharmacokinetic principles and imaging techniques for static and dynamic contrast-enhanced MR imaging and to highlight the most important indications for administration of gd-CM in patients with musculsokeletal tumors and tumor-like lesions: adding specificity in tissue characterization, staging of local extent and biopsy planning, monitoring preoperative chemotherapy and detection of recurrence.

Widening of the spinal canal and dural ectasia in Marfan's syndrome: assessment by CT

We describe a method for diagnosing dural ectasia (DE) and spinal canal widening (SCW) using CT. We examined 23 patients with Marfan's syndrome (MFS), 17 with Ehlers-Danlos syndrome (EDS) and 29 normal subjects, using six axial slices at the level of the L1-S1 pedicles. Transverse diameters of the vertebral bodies, spinal canal and dural sac were measured and indices were defined to differentiate patients with DE and SCW from normal. Statistical significance was assessed using Student's t -test, chi (2)-test and Pearson's correlation coefficient. DE and SCW occurred in 69.6 % and 60.9 % of cases of MFS and in 23.5 % and 35.3 % of EDS respectively. In MFS, prevalence was significantly higher than in the control group. DE was significantly more frequent in MFS than in EDS. A strong correlation existed between DE and SCW in MFS and the control group, but not in EDS. Our system enables quantitative assessment of SCW and DE. The latter is particularly important in subjects suspected of having MFS, in whom it is a common and characteristic sign.

Post-therapeutic magnetic resonance imaging of bone tumors

Magnetic resonance imaging plays an important role in the therapeutic follow-up of patients with bone tumors. Follow-up includes monitoring of response to neoadjuvant chemotherapy prior to limb salvage surgery, assessment of local recurrence of tumor, differentiation of suspected recurrence from hematopoietic bone marrow reconversion, inflammation, seroma, or reactive tissue, and detection of therapeutic complications, such as osteonecrosis, infection, and radiation-induced sarcoma. This article reviews the role of magnetic resonance imaging in the therapeutic follow-up of patients with bone tumors.

Musculoskeletal tumors: does fast dynamic contrast-enhanced subtraction MR imaging contribute to the characterization?

PURPOSE

To prospectively analyze the value of fast, dynamic, subtraction magnetic resonance (MR) imaging in the characterization of musculoskeletal tumors.

MATERIALS AND METHODS

In 175 consecutive patients with a musculoskeletal mass, dynamic contrast-enhanced subtraction MR imaging was performed after administration of 0.1 mmol per kilogram of body weight gadopentetate dimeglumine or gadoteridol. A turbo gradient-echo technique was used, with a temporal resolution of 1-3 seconds. The interval between arterial and early tumor enhancement, the pattern (peripheral or diffuse) of enhancement, and the progression of tumor enhancement, as visualized on time-signal intensity curves, were assessed. MR enhancement features were related to the histopathologic diagnoses.

RESULTS

Differentiation of benign from malignant soft-tissue masses was possible with a sensitivity of 91% and specificity of 72% based on start of enhancement, a sensitivity of 73% and specificity of 97% based on peripheral or diffuse enhancement, and a sensitivity of 86% and specificity of 81% based on progression of enhancement. Benign bone tumors could not be accurately differentiated from malignant bone tumors on the basis of the three defined parameters (sensitivity, 63%-76%; specificity, 50%-76%).

CONCLUSION

Dynamic, contract-enhanced, subtraction MR images may be useful to differentiate malignant from benign soft-tissue masses.

Current status and imaging of allograft meniscal transplantation

The authors present an overview of the current indications, techniques, results and complications of allograft meniscal transplantation. The radiologist's role in pre- and postoperative imaging is described. The spectrum of magnetic resonance imaging findings of meniscal allografts are illustrated.

Primary tumors of the musculoskeletal system

The excellent soft-tissue contrast and multiplanar imaging capabilities of MR imaging have led to its emergence as the most significant advance in the imaging of musculoskeletal tumors. MR imaging is the modality of choice for local staging, evaluating response to preoperative chemotherapy, and long-term follow-up in bone tumors. MR imaging is the most effective modality for both primary staging of soft-tissue malignancy and detecting recurrences. This article reviews the role of conventional spin echo techniques versus newer techniques, and then discusses the indications in the diagnosis, staging, evaluation of preoperative chemotherapy, and detection of recurrences in bone and soft-tissue tumors.

Dynamic contrast-enhanced MR imaging of musculoskeletal tumors: basic principles and clinical applications

The purpose of this article is to review the basic principles and clinical applications of dynamic contrast-enhanced MRI in the musculoskeletal system. This method of physiologic imaging provides clinically useful information by depicting tissue vascularization and perfusion, capillary permeability, and composition of the interstitial space. Different imaging, evaluation, and postprocessing techniques are described. The most important applications in the musculoskeletal system are identification of areas of viable tumor for biopsy, tissue characterization, and monitoring of preoperative chemotherapy. Practical guidelines for performing a dynamic contrast-enhanced MR examination are proposed.

Osteosarcoma and Ewing's sarcoma after neoadjuvant chemotherapy: value of dynamic MR imaging in detecting viable tumor before surgery

OBJECTIVE

This study analyzed the value of dynamic contrast-enhanced and subtraction MR images in detecting residual viable tumor before surgery, with emphasis on timing of enhancement, in patients with high-grade osteosarcoma and Ewing's sarcoma after neoadjuvant chemotherapy.

SUBJECTS AND METHODS

Twenty-one patients with proved osteosarcoma or Ewing's sarcoma were treated with neoadjuvant chemotherapy followed by surgery. After IV administration of gadopentetate dimeglumine, dynamic enhancement patterns on preoperative MR images were compared with corresponding areas on histologic sections of the resected specimens. On dynamic subtraction images obtained with high temporal resolution (1.5-3 sec), the interval between arrival of the bolus of contrast agent in an artery and start of tumoral enhancement was used to distinguish residual viable tumor. Early enhancing foci (interval artery-tumor < 6 sec) and late or nonenhancing areas seen on MR images were correlated with the histopathologic findings in these areas of the resected specimens.

RESULTS

Early and progressively enhancing structures seen on MR images corresponded to feeding arteries, physeal vessels, or residual viable tumor at specific preferential sites on corresponding histologic sections of the resected specimens. Tumor foci as small as 3-5 mm2 could be detected on dynamic MR images. Remnant viable tumor was often located subperiosteally and at the margins of the tumor. Occasionally, active periosteal reaction without presence of viable tumor contributed to early enhancement. Late and gradually enhancing or nonenhancing areas corresponded histopathologically to regions of chemotherapy-induced necrosis, mucomyxoid degeneration, or fibrosis. Alternatively, late or nonenhancing areas were associated with reactive changes such as edema, hemorrhage, or osteomyelitis or with tumor-related extracellular matrices such as abundant osteoid or chondroid. Viable tumor areas with scarce formation of matrix on microscopy, such as small cell osteosarcoma areas or Ewing's sarcoma, showed early enhancement with rapid washout of contrast agent on the dynamic MR images.

CONCLUSION

Fast dynamic contrast-enhanced sequences are essential for identifying residual tumor before surgery. A short time interval of less than 6 sec between arterial enhancement and tumoral enhancement strongly correlates with presence of viable tumor. Both therapy-related alterations of tissue and tumor-related matrices must be considered when late or lack of enhancement is noted on dynamic MR images.

Static, dynamic and first-pass MR imaging of musculoskeletal lesions using gadodiamide injection

Forty-five patients with known or suspected musculoskeletal tumors were examined with static and dynamic MR imaging to evaluate the safety, tolerability and diagnostic utility of gadodiamide injection and to assess the diagnostic value of dynamic MR imaging and parametric "first-pass" (FP) images. The proportion of patients presenting more diagnostic information on the contrast-enhanced compared to the precontrast spin-echo examinations was determined. The dynamic enhancement characteristics were evaluated with time-intensity curves and parametric images of the FP enhancement rate. The tolerance of gadodiamide injection was good. Contrast enhancement was useful for delineating tumor from muscle, and differentiating viable from necrotic tissue and cystic from solid lesions. Malignant tumors showed a significantly higher slope value, earlier onset of enhancement, and higher maximum enhancement than benign lesions. However, slope values could not be used to predict the malignant potential of a lesion, due to overlap between highly vascular benign and low vascular malignant lesions. By displaying highly vascular areas, parametric FP images provided useful information on the most active part in a tumor before biopsy and for assessing the incorporation of bone-chip allografts. Static, dynamic and FP MR imaging using gadodiamide injection appears safe and provides useful information for diagnosis, biopsy and follow-up of musculoskeletal lesions.

Benign and malignant musculoskeletal lesions: dynamic contrast-enhanced MR imaging--parametric "first-pass" images depict tissue vascularization and perfusion

PURPOSE

To assess the diagnostic value of parametric magnetic resonance images that display the first pass (FP) of gadopentetate dimeglumine.

MATERIALS AND METHODS

Dynamic, contrast material-enhanced, fast low-angle shot MR imaging was performed of 100 musculoskeletal lesions in 36 female and 64 male patients (aged 9-81 years [mean, 34 years]). The highest slope value of the time-intensity curve was calculated pixel by pixel and displayed on the FP image, with a gray-scale value equal to the slope value. Tissue vascularization and perfusion were evaluated at pathologic and angiographic examinations in 33 lesions.

RESULTS

A significant difference (P < .001) was found between the FP slope values of benign (mean, 36.2% per second) and malignant (mean, 67.4% per second) lesions. FP images depicted tissue vascularization and perfusion rather than benignity or malignancy, because there is an overlap in the slope values of highly vascular benign lesions and malignant lesions.

CONCLUSION

FP images provide diagnostically useful information by depicting tissue vascularization and perfusion.

First-pass images of musculoskeletal lesions: a new and useful diagnostic application of dynamic contrast-enhanced MRI

The purpose of this study was to evaluate the diagnostic value of parametric images which display the first-pass of Gd-DTPA after intravenous bolus injection. Single slice dynamic contrast-enhanced MRI (Turbo-FLASH) with a temporal resolution of 2.41 s was performed in 40 benign and malignant musculoskeletal lesions. Parametric 'first-pass' images were obtained by using a new postprocessing technique, derived from a home written computer program, which calculated the steepest slope of the time-intensity curve pixel by pixel. First-pass images provided qualitative and quantitative information, which was useful for diagnosis and therapy. Demonstration of the areas with the highest vascularization was very helpful in planning the best biopsy site in 6 patients and to delineate tumor from peritumoral muscle edema in 4 patients. In 10 patients the first-pass images provided additional information, which was not visible on the conventional spin-echo images. The most promising application was the ability to evaluate the response to preoperative chemotherapy in a patient with Ewing's sarcoma. Although a highly statistically significant difference (p < 0.001) was found between the first-pass slope values of benign and malignant lesions, the sensitivity (77%) and specificity (71%) of this method were too low to permit a definite differentiation of highly vascular benign from malignant lesions. Pathologic examination of 17 lesions, performed in the plane of the first-pass image, showed a good correlation between the first-pass slope values and the vascularization of the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Nerve sheath tumors: evaluation with CT and MR imaging

Tumors of nerves are classified into benign (schwannoma and neurofibroma) and malignant nerve sheath tumors. Schwannomas almost always occur as solitary lesions, whereas neurofibromas may occur alone or in a greater number, especially in patients with the peripheral form of von Recklinghausen's disease. Benign nerve sheath tumors often present as asymptomatic, slowly growing soft tissue masses. Although malignant nerve sheath tumors are relatively rare, a sudden increase in the size of a lesion, in particular in a patient with neurofibromatosis, should raise the suspicion of malignant change. On computed tomography (CT) and magnetic resonance imaging (MR) a benign nerve sheath tumor usually appears as a well-defined, oval, spherical or fusiform mass with smooth borders and distinct outlines, located in the subcutaneous tissue or centered at the expected anatomic location of a nerve, with displacement of adjacent soft tissues. Generally nerve sheath tumors have a low density on unenhanced CT scans. On MR they are isointense to muscle on T1-weighted images, whereas on T2-weighted images the signal intensity is high. Both on CT and MR the degree of contrast enhancement is moderate to marked and may be homogeneous or inhomogeneous. MR has become the method of choice for evaluating the anatomic location, contour, and relation of a nerve sheath tumor to adjacent neural, vascular, and muscular structures. The imaging criteria for malignant nerve sheath tumors are not specific enough to distinguish them from other malignant soft tissue tumors, so that neither CT nor MR can establish a definite diagnosis.

Traumatic lumbosacral nerve root meningoceles. The value of myelography, CT and MRI in the assessment of nerve root continuity

A case of traumatic lumbar meningoceles at four levels in combination with total and partial nerve root avulsion and with preservation of a nerve root is reported. Several diagnostic imaging techniques (myelography, CT, myelo-CT and MRI) are compared and their value in demonstrating the continuity of the nerve roots is discussed. MRI could assess the continuity of a nerve root in a traumatic meningocele, not demonstrable by myelography or myelo-CT. The combination of myelography, myelo-CT and MRI is likely to provide a complete diagnostic evaluation of nerve root lesions.