Pathological fracture in paediatric bone tumours and tumour-like lesions: A predictor of benign lesions?

Objective:To determine the incidence and causes of pathological fractures in paediatric bone tumours and tumour-like lesions, and to determine if they are predictive of benign lesions.Methods and materials:Retrospective review of children with suspected bone tumours referred to a specialist musculoskeletal oncology service between September 2019 and August 2020. Data recorded included patient age and gender, lesion location, the presence of a pathological fracture on the initial plain radiograph, and the final diagnosis made either by image-guided biopsy/curettage or based on typical imaging features.Results:231 patients were included with 233 lesions (138 males and 93 females with mean age 10.5 years, range 3 months–18 years). Final diagnosis was based on histology in 85 (36.5%) cases and imaging in 148 (63.5%) cases, 52 (22.3%) lesions classed as non-neoplastic, 139 (59.7%) as benign and 42 (18%) as malignant. Pathological fractures were seen in 41 cases (17.6%) at presentation, involving the humerus in 19 (46.3%), the femur in 14 (34.1%), the tibia in 3 (7.3%), the fibula and radius in two each (4.9%) and the second toe proximal phalanx in 1 (2.4%) (p < 0.001). The commonest underlying lesions included simple bone cyst (n = 17; 41.5%) and non-ossifying fibroma (n = 10; 24.4%). Only 4 cases (9.75%) were malignant, one case each of osteosarcoma, Ewing sarcoma, leukaemia and BCOR undifferentiated round cell sarcoma. Pathological fracture occurred in 27.7% of non-malignant lesions and 9.5% of malignant lesions, this difference being statistically significant (p < 0.001).Conclusion:Pathological fractures were seen in 17.6% of paediatric bone tumours, tumour-like lesions, being significantly associated with humeral location and non-malignant diagnosis.Advances in knowledge:Demonstrates the frequency, location and underlying diagnosis of pathological fractures in paediatric bone tumour and tumour-like lesions.     

Paediatric bone lesions: diagnostic accuracy of imaging correlation and CT-guided needle biopsy for differentiating benign from malignant lesions

Objective:To determine the sensitivity, specificity and accuracy of CT-guided needle biopsy (CT-NB) for distinguishing benign and malignant lesions in children with suspected primary bone tumours, and to assess the correlation between imaging diagnosis and final diagnosis.Methods:Retrospective review of children who underwent CT-NB of a suspected primary bone tumour between October 2016 and October 2019. Data collected included anatomical location, imaging diagnosis, type of needle, type of biopsy sample, CT-NB diagnosis, final diagnosis and post-procedural complications. The final diagnosis was established based on surgical histology or clinical/imaging follow-up.Results:125 patients met the inclusion criteria (68M, 57F: mean age 11 years; range 10 months–18 years). Biopsy was performed using a 10 cm Jamshidi needle (10G n = 96; 13 G n = 8); 14G Tru-Cut needle (n = 18); 14G Temno needle (n = 3). The commonest anatomical locations were the femur (n = 40), tibia (n = 25) and humerus (n = 16), while the commonest diagnoses were osteosarcoma (n = 35), CRMO (n = 15) and LCH (n = 14). A benign tumour was correctly identified on imaging in 100% of cases, and a malignant tumour in 95.8%. Sensitivity, specificity and diagnostic accuracy of CT-NB for distinguishing malignant from benign lesions were 98%, 100 and 99%. Of 24 indeterminate biopsy results, all that had a non-aggressive radiological appearance were benign. No immediate complications were recorded.Conclusion:CT-NB represents a safe and very effective tool for differentiating benign and malignant lesions in children presenting with a suspected primary bone tumour. Suspected radiological diagnosis plays a pivotal role in the management of indeterminate biopsy results.Advances in knowledge:Paediatric bone tumours pose a significant diagnostic and therapeutic challenge. The interpretation of the imaging findings is essential for the successful management of indeterminate histological results.     

MRI of bone marrow oedema associated with focal bone lesions

AIM: To quantify the volume of bone marrow oedema surrounding focal bone lesions and to identify its relevance relative to diagnosis. METHODS: Three hundred and eighty-eight of 1456 patients included in the orthopaedic oncology database who underwent magnetic resonance imaging (MRI) demonstrated bone marrow oedema and were included in the study. There were 225 males and 163 females, age range 1-87 years (mean 29 years). MRI images were retrospectively reviewed and assessed for the extent of bone marrow oedema. The amount of oedema was graded: grade 1: oedema present but smaller than the lesion size; grade 2: oedema equivalent to the lesion size; grade 3: oedema greater than the lesion size. RESULTS: There were 190 grade 1 lesions: 56% malignant, 33% benign, 11% non-neoplastic; 74 grade 2 lesions: 19% malignant, 50% benign, 31% non-neoplastic; and 124 grade 3 lesions: 10% malignant, 46% benign, 44% non-neoplastic. There was a significant relationship between oedema grade (i.e., volume of oedema) and final diagnosis (p<0.0005). CONCLUSION: Bone marrow oedema may be associated with a wide range of focal bony lesions, including malignant, benign and non-neoplastic causes. As the volume of bone marrow oedema increases relative to the size of the underlying lesion, the probability that the underlying lesion is benign is increased.     

Proton density fat fraction (PDFF) MRI for differentiation of benign and malignant vertebral lesions

Objectives

To investigate whether proton density fat fraction (PDFF) measurements using a six-echo modified Dixon sequence can help to differentiate between benign and malignant vertebral bone marrow lesions.

Methods

Sixty-six patients were prospectively enrolled in our study. In addition to conventional MRI at 3.0-Tesla including at least sagittal T2-weighted/spectral attenuated inversion recovery and T1-weighted sequences, all patients underwent a sagittal six-echo modified Dixon sequence of the spine. The mean PDFF was calculated using regions of interest and compared between vertebral lesions. A cut-off value of 6.40% in PDFF was determined by receiver operating characteristic curves and used to differentiate between malignant (< 6.40%) and benign (≥ 6.40%) vertebral lesions.

Results

There were 77 benign and 44 malignant lesions. The PDFF of malignant lesions was statistically significant lower in comparison with benign lesions (p < 0.001) and normal vertebral bone marrow (p < 0.001). The areas under the curves (AUC) were 0.97 for differentiating benign from malignant lesions (p < 0.001) and 0.95 for differentiating acute vertebral fractures from malignant lesions (p < 0.001). This yielded a diagnostic accuracy of 96% in the differentiation of both benign lesions and acute vertebral fractures from malignancy.

Conclusion

PDFF derived from six-echo modified Dixon allows for differentiation between benign and malignant vertebral lesions with a high diagnostic accuracy.

Key Points

? Establishing a diagnosis of indeterminate vertebral lesions is a common clinical problem? Benign bone marrow processes may mimic the signal alterations observed in malignancy? PDFF differentiates between benign and malignant lesions with a high diagnostic accuracy? PDFF of non-neoplastic vertebral lesions is significantly higher than that of malignancy? PDFF from six-echo modified Dixon may help avoid potentially harmful bone biopsy

     

Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging for Differentiation Between Parotid Neoplasms

PurposeThis study was designed to evaluate the role of multiparametric magnetic resonance imaging (MRI) for differentiation of parotid gland neoplasms.MethodsProspective study was conducted upon 52 consecutive patients (30 men, 22 women; aged 24–78 years; mean, 51 years) with parotid tumours that underwent multiparametric MRI using combined static MRI, dynamic contrast enhanced (DCE) MRI, and diffusion-weighted imaging (DWI). The static MRI parameter, time signal intensity curves (TIC) derived from DCE-MRI, and apparent diffusion coefficient (ADC) values of parotid tumours were correlated with histopathological findings.ResultsStatic MRI revealed a significant difference between both benign and malignant lesions in regards to margin definition (P < .001) and T2 hypointensity (P < .013), with a diagnostic accuracy 95% and 78.33% respectively. Study of the TIC type on DCE-MRI revealed statistically significant difference between benign and malignant lesions (P < .001) and diagnostic accuracy 96.55%. There was no statistically significant difference (P = .181) between the ADC values of benign and malignant lesions. ROC curve analysis revealed that by using ADC cut-off value of 1 × 10^?3 mm²/s had accuracy of 84.62% respectively for differentiating Warthin from malignant tumours that could be modified to higher value (94.28%) by excluding lymphoma from malignant lesions. By using cutoff value of 1.3 × 10^?3 mm²/s to differentiate pleomorphic adenoma from malignancy, ROC curve analysis had high accuracy of 97.06%.ConclusionMultiparametric MRI can be used for differentiation of malignant from benign parotid tumours and characterization of some benign parotid tumours.     

Comparison of the Diagnostic Value of Mono-exponential,Bi-exponential,and Stretched Exponential Signal Models in Diffusion-weighted MR Imaging for Differentiating Benign and Malignant Hepatic Lesions

Purpose:To compare the diagnostic value of mono-exponential, bi-exponential, and stretched exponential diffusion-weighted imaging (DWI) for differentiating benign and malignant hepatic lesions.Methods:This prospective study was approved by our Institutional Review Board and the patients provided written informed consent. Magnetic resonance imaging was acquired for 56 patients with suspected liver disease. This identified 90 focal liver lesions with a maximum diameter >10 mm, of which 47 were benign and 43 were malignant. Using home-built software, two radiologists measured the DWI parameters of hepatic lesions for three models: the apparent diffusion coefficient (ADC) from a mono-exponential model; the true diffusion coefficient (D), pseudo-diffusion coefficient (D^*), and perfusion fraction (f) from a bi-exponential model; and the distributed diffusion coefficient (DDC) and water molecular diffusion heterogeneity index (α) from a stretched exponential model. The parameters were compared between benign and malignant hepatic lesions.Results:ADC, D, D^*, f, and DDC values were significantly lower for malignant hepatic lesions than for benign lesions (P < 0.0001–0.03). Although logistic regression analysis demonstrated that DDC was the only statistically significant parameter for differentiating benign and malignant lesions (P = 0.039), however, the areas under the receiver operating characteristic curve for differentiating benign and malignant lesions were comparable between ADC (0.98) and DDC (0.98) values.Conclusion:DDC values obtained from the stretched exponential model could be also used as a quantitative imaging biomarker for differentiating benign and malignant hepatic lesions, however, the diagnostic performance was comparable with ADC values.     

Diagnostic value of apparent diffusion coefficient to differentiate benign from malignant vertebral bone marrow lesions

Background

Vertebral collapse is a common problem due to benign bone marrow lesions, trauma or malignant process. The diagnosis is often correctly predicted from characteristic imaging appearance. Some vertebral collapses have atypical imaging appearance that may cause diagnostic confusion.

Aim

To evaluate the value of the ADC obtained in DW-MR sequences for the differentiation between benign and malignant bone marrow lesions.

Patients

Sixty patients were included in this study, referred from Neurosurgery and Radiotherapy Departments and proved to have vertebral compression based on conventional MR imaging.

Results

The ADC value resulted in statistically significant characterization between (osteoporotic and post-traumatic collapse) and (malignant vertebral collapse) (P < 0.0001) while there was no statistically significant findings between infective spondylodiscitis and malignant vertebral collapse (P > 0.05). The sensitivity, specificity, PPV, NPD of DWI and ADC values in differentiating benign from malignant vertebral collapse were 100%, 83.3%, 60% and 100% respectively.

Conclusions

ADC values are a useful complementary MRI tool to characterize bone marrow lesions, in order to distinguish acute benign fractures from malignant or infectious bone marrow lesions. However, ADC values are not valuable in order to differentiate malignancy from infection with diagnostic overlap in the subacute traumatic vertebral collapse.     

Contrast-enhanced magnetic resonance imaging of bone marrow

In the assessment with magnetic resonance (MR) imaging of bone marrow disorders, the use of contrast agents is usually not critical because T1-weighted spin-echo and fat-suppressed sequences (STIR or fat-sat intermediate weighted) are robust and largely available techniques for depiction of neoplastic and non-neoplastic lesions of the bone marrow. This article discusses the characteristics of dynamic contrast-enhanced MR imaging of bone marrow edema, ischemia, and neoplasm. It emphasizes its value in staging and in monitoring of response to chemotherapy of several bone tumors. These fast dynamic contrast-enhanced techniques do not allow differentiation between benign and malignant primary osseous tumors because the biologic behavior rather than the malignant potential of these lesions is reflected.     

Uptake of iodine-123-α-methyl tyrosine by gliomas and non-neoplastic brain lesions

Using single-photon emission tomography (SPET), the radiopharmaceuticall,-3-iodine-123--methyl tyrosine (IMT) has been applied to the imaging of amino acid transport into brain tumours. It was the aim of this study to investigate whether IMT SPET is capable of differentiating between high-grade gliomas, low-grade gliomas and non-neoplastic brain lesions. To this end, IMT uptake was determined in 53 patients using the triple-headed SPET camera MULTISPECT 3. Twenty-eight of these subjects suffered from high-grade gliomas (WHO grade III or IV), 12 from low-grade gliomas (WHO grade II), and 13 from non-neoplastic brain lesions, including lesions after effective therapy of a glioma (five cases), infarctions (four cases), inflammatory lesions (three cases) and traumatic haematoma (one case). IMT uptake was significantly higher in high-grade gliomas than in low-grade gliomas and non-neoplastic lesions. IMT uptake by low-grade gliomas was not significantly different from that by non-neoplastic lesions. Diagnostic sensitivity and specificity were 71% and 83% for differentiating high-grade from low-grade gliomas, 82% and 100% for distinguishing high-grade gliomas from non-neoplastic lesions, and 50% and 100% for discriminating low-grade gliomas from non-neoplastic lesions. Analogously to positron emission tomography with radioactively labelled amino acids and fluorine-18 deoxyglucose, IMT SPET may aid in differentiating high-grade gliomas from histologically benign brain tumours and non-neoplastic brain lesions; it is of only limited value in differentiating between non-neoplastic lesions and histologically benign brain tumours.     

Tumours and tumour-like lesions of joints: Differential diagnoses in a paediatric population compared to adults

Objective:To determine the differential diagnosis of intra-articular tumours and tumour-like lesions in a paediatric population compared to adults.Methods:Retrospective review of children up to the age of 18 years with suspected intra-articular tumours and tumour-like lesions referred to a specialist musculoskeletal oncology service from January 2019 to August 2020. Data recorded included patient age and gender, lesion location and morphology (based on the classification system of Adams et al.), and the final diagnosis made either by image-guided biopsy/resection or by clinical and imaging features. Comparison was then made with a group of adults presenting during the same period.Results:28 paediatric patients were included (12 males and 16 females with mean age 11.2 years, range 3–18 years). Joints involved were the knee (n = 22; 78.6%), ankle (n = 4; 14.3%), hip (n = 1; 3.6%) and elbow (n = 1; 3.6%). Lesion morphology was Type 1 (n = 18; 64.3%), Type 2 (n = 3; 10.7%), Type 3 (n = 1; 3.6%) and Type 4 (n = 5; 17.9%). Final diagnosis was made by image-guided biopsy/resection in 18 (64.3%) patients. The commonest neoplastic lesion was tenosynovial giant cell tumour (n = 11; 39.3%), followed by synovial haemangioma (n = 5; 17.9%). There was only a single malignant lesion, a case of synovial sarcoma. Of eight (28.6%) non-neoplastic lesions, three were diagnosed as juvenile idiopathic arthritis and three as non-specific synovitis. There was no difference compared to adults regarding gender, joint involved or lesion morphology, but there was a significant difference in final diagnoses (p < 0.001). The range of intra-articular tumours and tumour-like lesions in children differs from that in adults, although tenosynovial giant cell tumour is the commonest diagnosis in both groups and malignant lesions are rare.Advances in knowledgeart:In our series, ~16% of tumours and tumour-like lesions of joints occur in the paediatric population. Tenosynovial giant cell tumour remains the commonest diagnosis in children as in adults. Synovial haemangioma and juvenile idiopathic arthritis were the next commonest diagnoses in children, while primary synovial chondromatosis and reactive synovitis were the next commonest diagnoses in adults. Malignant lesions are rare in both groups.     

Diagnostic accuracy of apparent diffusion coefficient (ADC) value in differentiating malignant from benign solid liver lesions: a systematic review and meta-analysis

Objectives:We undertook a systematic review and meta-analysis of the diagnostic performance of mean apparent diffusion coefficient (ADC) values derived by diffusion-weighted (DW)-MRI in the characterization of solid benign and malignant liver lesions, and to assess their value in discriminating these lesions in daily routine practice.Methods:A systematic review of PubMed, Embase, Scopus, and Web of Science was conducted to retrieve studies that used ADC values for differentiating solid benign/dysplastic nodules and malignant liver lesions. A bivariate random-effects model with pooled sensitivity and specificity values with 95% CI (confidence interval) was used. This meta-analysis was performed on the per-lesion basis. Summary receiver operating characteristic (SROC) plot and area under curve (AUC) were created.Results:A total of 14 original articles were retrieved. The combined (95% CI) sensitivity and specificity of mean ADC values for differentiating solid benign from malignant lesions were 78% (67–86%) and 74% (64–81%), respectively. The pooled (95% CI) positive and negative LRs were respectively 3 (2.3–3.8) and 0.3 (0.21–0.43). The DOR (95% CI) was 10 (7–15). The AUC (95% CI) of the SROC plot was 82% (78–85%). Reporting bias was negligible (p value of regression test = 0.36). Mean size of malignant lesions and breathing pattern of MRI were found to be sources of heterogeneity of pooled sensitivity.Conclusion:ADC measurement independently may not be an optimal diagnostic imaging method for differentiating solid malignant from solid benign hepatic lesions. The meta-analysis showed that ADC measurement had moderate diagnostic accuracy for characterizing solid liver lesions. Further prospective and comparative studies with pre-specified ADC thresholds could be performed to investigate the best MRI protocol and ADC threshold for characterizing solid liver lesions.Advances in knowledge:ADC measurement by DW-MRI does not have a good diagnostic performance to differentiate solid malignant from solid benign lesions. Therefore, we suggest not using ADC values in clinical practice to evaluate solid liver lesions.     

A review of paediatric soft tissues masses referred to a tertiary musculoskeletal sarcoma centre

Objectives:To determine the differential diagnosis of musculoskeletal soft tissue masses in children referred to a specialist musculoskeletal oncology unit.Methods:All children (0–18 y) referred to a specialist musculoskeletal oncology unit over a 20-month period (September 2018–May 2020) were retrospectively reviewed. Demographic data and referral diagnoses were obtained from the electronic patient notes. MRI findings and histopathological results were recorded. The comparison of non-neoplastic, benign neoplastic and malignant diagnoses at the point of referral and final diagnosis was determined.Results:116 patients were included, 60 (51.7%) males and 56 (48.3%) females with mean age of 10.6 years (3 months–18 years). 69 (59.5%) patients were referred with a suspected sarcoma, 29 (25.0%) with a suspected benign tumour and 18 (15.5%) with a non-neoplastic lesion. A diagnosis was achieved by histological assessment in 61 (52.6%) cases, microbiological assessment in 3 (2.6%) or clinical and imaging assessment in 52 (44.8%). 67 (57.8%) cases had non-neoplastic pathology, 39 (33.6%) a benign tumour, 4 (3.4%) an intermediate-grade tumour, 6 (5.2%) a malignant tumour.Conclusions:Although over half of children referred to a specialist musculoskeletal oncology unit were suspected of having a soft tissue sarcoma at referral, only 5.2% were diagnosed with a malignant tumour.Advances in knowledge:Approximately, 6 of 69 (8.7%) children referred to a specialist musculoskeletal oncology unit with a suspected soft tissue sarcoma will have a malignant lesion. Most paediatric soft tissue masses are non-neoplastic, the commonest diagnosis being a vascular malformation.     

Prevalence and diagnostic significance of fluid-fluid levels in soft-tissue neoplasms

AIM: To report the prevalence of fluid-fluid levels (FFLs) in soft-tissue tumours as demonstrated by magnetic resonance imaging (MRI) and the potential diagnostic relevance of this finding. MATERIALS AND METHODS: A retrospective analysis was performed of 726 consecutive patients (361 women, 365 men, mean age 47.6 years+/-20.1 SD) presenting with a soft-tissue mass over a 7-year period. All subjects underwent MRI and final diagnosis was based on biopsy/surgical resection, or clinical follow-up and characteristic imaging findings. The patients were divided according to the presence or absence of FFLs on T2-weighted (T2W) axial MRI and histological diagnosis (non-neoplastic, neoplastic benign, neoplastic malignant). Cases with FFLs were sub-categorized depending upon the proportion of tumour containing FFLs: <1/3, 1/3-2/3 and >2/3, in order to determine whether the proportion of FFLs was useful for differential diagnosis. RESULTS: Twenty-four of the 726 (3.3%: confidence interval 2.1-4.9%) soft-tissue masses contained FFLs. One of the 24 (4.1%) was non-neoplastic (one ganglion), 12 (50.0%) were benign neoplasms (nine haemangiomas, two schwannomas, one hamartoma) and 11 (45.9%) were malignant neoplasms (one leiomyosarcoma, one liposarcoma, one malignant fibrous histocytoma, one mxyofibrosarcoma, two primitive neuroectodermal tumours, two synovial sarcomas, one spindle cell sarcoma, and two sarcomas not otherwise specified). The presence of FFLs did not help to differentiate benign from malignant neoplasms. Of the 12 benign neoplasms, 66.7% contained over two-thirds FFLs, the majority of which were haemangiomas. Of the 10 malignant neoplasms, all contained less than two-thirds FFLs: 20% had less than one-third, 80% had one to two-thirds FFLs. CONCLUSIONS: The prevalence of FFLs in soft-tissue tumours referred to a specialist orthopaedic oncology unit is 3.3%. However, the presence of FFLs does not reliably distinguish benign from malignant neoplasms, although all lesions with more than two-thirds FFLs were benign.     

MRI of soft-tissue masses: the relationship between lesion size, depth, and diagnosis

AIMS: To identify the relationship between depth and size of soft-tissue mass lesions relative to histological diagnosis in a range of malignant neoplastic, benign neoplastic, and non-neoplastic conditions on magnetic resonance imaging (MRI). METHOD: The MRI findings of 571 consecutive patients referred to a supra-regional orthopaedic oncology unit with a suspected soft-tissue neoplasm were reviewed and included in the study. The patient age, histological diagnosis, lesion size, anatomical location, and lesion depth (superficial or deep to fascia) were recorded. RESULTS: There were 288 males and 283 females (mean age 48 years, age range 2-92 years). The mean age was 54.1 years for malignant neoplastic lesions compared with 40.1 years for benign neoplastic and 45.4 years for non-neoplastic conditions. There was a significant age difference when malignant lesions were compared with benign neoplastic and non-neoplastic lesions (p<0.001). No significant relationship was present between lesion depth (480 deep, 91 superficial) and diagnosis (288 malignant neoplastic, 197 benign neoplastic and 86 non-neoplastic lesions). However, a significant relationship was identified between lesion size and diagnosis (p<0.001). Furthermore, a significant relationship was identified when lesion size greater than 5 cm, lesion depth, and diagnosis were analysed. CONCLUSION: Current guidelines suggest the most important variables for assessing risk of malignancy in a soft-tissue lesion include size, depth in relation to the fascia, increasing size, and pain. The current study suggests that relationship to fascia is less important as a predictor of malignant potential in a patient cohort treated at a supra-regional centre. Significant risk factors include increasing patient age and lesion size greater than or equal to 5 cm.     

Role of diffusion-weighted MR imaging in assessing malignant versus benign skull-base lesions

Purpose

This study was done to assess the role of diffusion-weighted magnetic resonance (MR) imaging in assessing malignant versus benign skull lesions.

Materials and methods

A retrospective analysis was undertaken of 45 patients (26 male, 19 female; age range 14?C68 years, mean age 39 years) with skull-base lesions. Diffusion-weighted MR images were acquired with a bfactor of 500 and 1,000 s/mm² using single-shot echoplanar imaging. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the lesion was calculated.

Results

The mean ADC value of malignant tumours was (1.002±0.21)×10^?3 mm²/s and that of benign tumours was (1.63±0.29)×10^?3 mm²/s. There was a statistically significant difference (p=0.001) in the ADC value of malignant skull-base tumours versus benign lesions. Selection of (1.3)×10^?3mm²/s as a threshold value of ADC for differentiating benign from malignant tumours yielded the best result, with an accuracy of 94%, sensitivity of 94%, specificity of 93%, positive predictive value of 93%, negative predictive value of 94% and area under the curve of 0.932.

Conclusions

We conclude that diffusion-weighted MR imaging is a promising, noninvasive approach that can be used to characterise skull-base lesions in that it can help differentiate malignant tumours from benign lesions and evaluate the pathological grading of malignant tumours.     

Bone marrow oedema associated with benign and malignant bone tumours

Bone marrow oedema is associated with a wide variety of pathological processes including both benign and malignant bone tumours. This imaging finding in relation to intraosseous tumours can aid in providing a more focused differential diagnosis. In this review, we will discuss the MR imaging of bone marrow oedema surrounding intraosseous neoplasms. The different pulse sequences used in differentiating underlying tumour from surrounding oedema are discussed along with the role of dynamic contrast enhanced MRI. Benign lesions commonly associated with bone marrow oedema include osteoid osteoma, osteoblastoma, chondroblastoma and Langerhan's cell histiocytosis. Metastases and malignant primary bone tumours such as osteosarcoma, Ewing's sarcoma and chondrosarcoma may also be surrounded by bone marrow oedema. The imaging findings of these conditions are reviewed and illustrated. Finally, the importance of bone marrow oedema in assessment of post chemotherapeutic response is addressed.     

Evaluation of computer-assisted diagnosis of small pulmonary nodules using contrast-enhanced dynamic helical CT

Dynamic helical computed tomography(DH-CT) was performed to examine 45 lesions(23 lung cancers, 2 pulmonary metastasis, and 20 benign nodules) as an application of computer-assisted qualitative analysis of small pulmonary nodules. Based on the three-dimensional(3D) CT image data, the internal structure of the nodule was assessed quantitatively and temporal changes were evaluated. The entire lesion was examined by helical scanning with a beam width of 2 mm(pitch of 1) before contrast enhancement and 2 and 4 minutes after contrast enhancement. Using the digital CT data, the pixels inside the nodules were quantified based on a combination of CT values and 3D curvature in order to differentiate between benign(BN) and malignant nodules (MN). (The numeral score abovementioned was calculated.) The average scores for BN 2 and 4 minutes were -5.72 and -12.8, respectively, and those for MN were 5.51 and 12.0, respectively(p < 0.01). Assuming that a score of 0 or higher indicates a MN based on the CT data 4 minutes. In conclusion, 3D computer-assisted analysis of the internal structure of small pulmonary nodules using contrast-enhanced DH-CT was found to be effective for differentiating between benign and malignant nodules.     

The prevalence and diagnostic significance of fluid-fluid levels in focal lesions of bone

Objective To determine the prevalence and diagnostic significance of fluid-fluid levels (FFLs) in focal bone lesions.Design and patients Clinical and radiological details of 738 consecutive patients referred with focal lesions of bone and who had undergone MRI were reviewed. FFLs were identified in 83 (11.2%). The proportion of the lesion occupied by FFLs was estimated, based on imaging in all available planes, as <1/3, 1/3–2/3, >2/3 but not the entire lesion, and complete. The degree of FFL change in each lesion was correlated with the final diagnosis, which was either histological (n=80) or clinicoradiological (n=3). There were 31 female and 52 male patients, mean age 25.5 years (range 5–83 years).Results Histology revealed 46 benign, 32 malignant and 2 non-neoplastic lesions. A clinicoradiological diagnosis was made in the 3 lesions without histology: 2 were benign (simple bone cyst and intraosseous lipoma) and 1 malignant (a metastasis). Malignant neoplasms commonly showed FFLs which occupied <1/3 of the entire lesion (n=22/32, 68.8%), and 50% of all the lesions in this group were conventional intramedullary osteosarcomas (n=16). With increasing FFL change, malignancy became less frequent: with >2/3 (but incomplete) FFL change, 81% (n=13/16) of tumours were benign. If the entire tumour showed FFL change, the histology was benign in 100% (n=11).Conclusions The extent of FFLs within a focal bone lesion appears to be inversely related to the degree of malignancy. If at least 2/3 of the lesion shows FFL change, 89% of diagnoses are benign.     

Detection and quantification of focal uptake in head and neck tumours: 18F-FDG PET/MR versus PET/CT

Purpose

Our objectives were to assess the quality of PET images and coregistered anatomic images obtained with PET/MR, to evaluate the detection of focal uptake and SUV, and to compare these findings with those of PET/CT in patients with head and neck tumours.

Methods

The study group comprised 32 consecutive patients with malignant head and neck tumours who underwent whole-body ¹⁸F-FDG PET/MR and PET/CT. PET images were reconstructed using the attenuation correction sequence for PET/MR and CT for PET/CT. Two experienced observers evaluated the anonymized data. They evaluated image and fusion quality, lesion conspicuity, anatomic location, number and size of categorized (benign versus assumed malignant) lesions with focal uptake. Region of interest (ROI) analysis was performed to determine SUVs of lesions and organs for both modalities. Statistical analysis considered data clustering due to multiple lesions per patient.

Results

PET/MR coregistration and image fusion was feasible in all patients. The analysis included 66 malignant lesions (tumours, metastatic lymph nodes and distant metastases), 136 benign lesions and 470 organ ROIs. There was no statistically significant difference between PET/MR and PET/CT regarding rating scores for image quality, fusion quality, lesion conspicuity or anatomic location, number of detected lesions and number of patients with and without malignant lesions. A high correlation was observed for SUV_mean and SUV_max measured on PET/MR and PET/CT for malignant lesions, benign lesions and organs (ρ?=?0.787 to 0.877, p?<?0.001). SUV_mean and SUV_max measured on PET/MR were significantly lower than on PET/CT for malignant tumours, metastatic neck nodes, benign lesions, bone marrow, and liver (p?<?0.05). The main factor affecting the difference between SUVs in malignant lesions was tumour size (p?<?0.01).

Conclusion

In patients with head and neck tumours, PET/MR showed equivalent performance to PET/CT in terms of qualitative results. Comparison of SUVs revealed an excellent correlation for measurements on both modalities, but underestimation of SUVs measured on PET/MR as compared to PET/CT.     

Late Effects of Cyclophosphamide and Total Body Irradiation as a Conditioning Regimen for Bone Marrow Transplantation in Rats (a Preliminary Report)

Summary

The longterm survival and occurrence of neoplastic and nonneoplastic lesions following total body irradiation (TBI), 8·5 Gy, with or without additional cyclophosphamide (Cy; 100 mg kg^?1 i.p.) treatment as a conditioning regimen for bone marrow transplantation (BMT) were studied in male BN/BiRij rats.

The two groups of rats that were treated with Cy (Cy and Cy + TBI) that survived beyond 100 days after treatment, had a severely decreased median (post treatment) survival time (Cy + TBI: 14·5 months and Cy: 14·1 months). Survival time in the TBI group was moderately decreased (18·5 months) as compared with the untreated controls (27·2 months). All treatment modalities were carcinogenic according to the raw data. After Cy-treatment a high incidence of, frequently multiple, malignant nerve-sheath tumours (Cy: 66 per cent, Cy + TBI: 31 per cent, controls: 2 per cent) was observed.

TBI induced an increased occurrence of a great variety of tumours, especially mesenchymal tumours. This effect was more pronounced in animals receiving TBI alone as compared to animals receiving the combined treatment of Cy + TBI; an effect that most likely resulted from the longer median survival after TBI. The multi-target effect of TBI was also reflected in the occurrence of nonneoplastic effects in a variety of tissues, including high incidences of biliary cysts in the liver and severe testicular atrophy.

The most important Cy-induced nonneoplastic lesion was incisor dysplasia, which resulted in feeding problems that could only be partly overcome by administering powdered food. Early mortality in the Cy-treated groups was associated with emaciation and generalized organ atrophy.

A more definitive estimate of the late effects of supralethal chemoradiotherapy as part of a treatment of malignant disease has to await the results of various conditioning regimens for BMT in rats employing the acute BN myelocytic leukaemia (BNML) as a rat model for human acute myelocytic leukaemia (AML).