Diffusion-weighted imaging with histogram analysis of the apparent diffusion coefficient maps in the diagnosis of parotid tumours.

The aim of this study was to investigate the role of diffusion-weighted imaging (DWI) with histogram analysis of apparent diffusion coefficient (ADC) maps in the characterization of parotid tumours. This prospective study included 39 patients with parotid tumours. All patients underwent magnetic resonance imaging with DWI, and ADC maps were generated. The whole lesion was selected to obtain histogram-related parameters, including the mean (ADCmean), minimum (ADCmin), maximum (ADCmax), skewness, and kurtosis of the ADC. The final diagnosis included pleomorphic adenoma (PA; n=18), Warthin tumour (WT; n=12), and salivary gland malignancy (SGM; n=9). ADCmean (×10-3mm2/s) was 1.93±0.34 for PA, 1.01±0.11 for WT, and 1.26±0.54 for SGM. There was a significant difference in whole lesion ADCmean among the three study groups. Skewness had the best diagnostic performance in differentiating PA from WT (P=0.001; best detected cut-off 0.41, area under the curve (AUC) 0.990) and in discriminating WT from SGM (P=0.03; best detected cut-off 0.74, AUC 0.806). The whole lesion ADCmean value had best diagnostic performance in differentiating PA from SGM (P=0.007; best detected cut-off 1.16×10-3mm2/s, AUC 0.948). In conclusion, histogram analysis of ADC maps may offer added value in the differentiation of parotid tumours.

DTI of the Olfactory Bulb in COVID-19-Related Anosmia: A Pilot Study.

This study aimed to assess the utility of DTI in the detection of olfactory bulb dysfunction in COVID-19-related anosmia. It was performed in 62 patients with COVID-19-related anosmia and 23 controls. The mean diffusivity and fractional anisotropy were calculated by 2 readers. The difference between the fractional anisotropy and mean diffusivity values of anosmic and control olfactory bulbs was statistically significant (P = .001). The threshold of fractional anisotropy and mean diffusivity to differentiate a diseased from normal olfactory bulb were 0.22 and 1.5, with sensitivities of 84.4% and 96.8%, respectively, and a specificity of 100%.

Radiolabeling, characterization, and preclinical evaluation of plazomicin: A potential tracer for bacterial infection.

In this study, 99m Tc-plazomicin, a new radio-antibiotic complex, was prepared specifically for bacterial infection localization and monitoring. Factors affecting the labeling reaction were studied and optimized to obtain a high yield (98.8 ± 0.2%). In silico, radiochemical and physicochemical characterization and biodistribution were performed to assess the complex aptness as a radiopharmaceutical. The complex was biologically evaluated in vitro using bacteria and in vivo using different inflammation models (sterile, bacterial, and fungal). Uptake in the bacterial model was highest (7.8 ± 0.3%). Results indicated that the technetium label did not alter the antibiotic biological behavior and backed the usefulness of 99m Tc-plazomicin as a potential tracer.

Prediction of skull base osteomyelitis in necrotising otitis externa with diffusion-weighted imaging.

OBJECTIVE: To predict skull base osteomyelitis in patients with necrotising otitis externa using diffusion-weighted imaging. METHODS: A retrospective analysis was conducted of 25 necrotising otitis externa patients with skull base osteomyelitis (n = 10) or without skull base involvement (n = 14) who underwent a single-shot diffusion-weighted imaging of the skull base. RESULTS: The respective mean apparent diffusion coefficient values of the skull base, as determined by two reviewers, were 0.851 ± 0.15 and 0.841 ± 0.14 ×10-3mm2/s for the skull base osteomyelitis patients, and 1.065 ± 0.19 and 1.045 ± 0.20 ×10-3mm2/s for the necrotising otitis externa patients without skull base involvement. The difference in apparent diffusion coefficients between the groups was significant, for both reviewers (p = 0.008 and 0.012). The optimal threshold apparent diffusion coefficient for predicting skull base osteomyelitis in necrotising otitis externa patients was 0.945 ×10-3mm2/s and 0.915 ×10-3mm2/s, with an area under the curve of 0.825 and 0.800, accuracy of 87.5 and 83.3 per cent, sensitivity of 85.7 and 90.0 per cent, and specificity of 90.0 and 78.6 per cent, for each reviewer respectively. CONCLUSION: Apparent diffusion coefficient is a non-invasive imaging parameter useful for predicting skull base osteomyelitis in necrotising otitis externa patients.

Reproducibility of LI-RADS treatment response algorithm for hepatocellular carcinoma after locoregional therapy.

PURPOSE: To determine inter-reader agreement in categorizing hepatocellular carcinoma (HCC) treated with locoregional therapy using the Liver Imaging Reporting and Data System (LI-RADS) treatment response (LR-TR) algorithm. MATERIALS AND METHODS: A total of 93 patients with a total of 112 HCC nodules that were treated using thermal ablation or transarterial chemoembolization were prospectively included. There were 79 men and 14 women with a mean age of 55±2.6 (SD)years (range: 48-63years). All patients underwent magnetic resonance imaging (MRI) examination of the liver and MR images were analyzed by two independent observers. Treated HCC nodules were categorized into four groups according to LR-TR scoring system including: (i) LR-TR non-evaluable (treated, response not evaluable); (ii) LR-TR nonviable (treated, probably or definitively not viable); (iii) LR-TR equivocal (treated, equivocally viable) and (iv) LR-TR viable (treated, probably or definitively viable). The inter-observer agreement in LR-TR categorization was assessed using the kappa statistics. RESULTS: There was excellent inter-observer agreement between the two reviewers for overall treated HCC according to LR-TR algorithm (kappa=0.938; 95% CI: 0.89-1.00; P=0.001) with 97.31% agreement. The LR-TR categories by both reviewers were non-viable (77/112; 69.6% and 76/112; 67.9%), viable (30/112; 26.8% and 32/112; 27.7%) and equivocal (5/112; 4.4% and 4/112; 3.6%). There was excellent inter-observer agreement for LR-TR nonviable (kappa=0.938; 95% CI: 0.87-1.0; P=0.001) with 97.3% agreement, LR-TR viable (kappa=0.955; 95% CI: 0.89-1.00; P=0.001) with 98.2% agreement and good inter-observer agreement for LR-TR equivocal (kappa=0.700; 95% CI: 0.28-1.0; P=0.001) with 97.3% agreement. CONCLUSION: LR-TR algorithm conveys high degrees of inter-observer agreement for the evaluation of treatment response of HCC after thermal ablation and transarterial chemoembolization.

Intra-articular injection of a mixture of hyaluronic acid and corticosteroid versus arthrocentesis in TMJ internal derangement.

BACKGROUND: Internal derangements are the commonest disorders of temporomandibular joint (TMJ). Different treatment modalities have been proposed to treat this disorder. Arthrocentesis and intra-articular injection are gaining popularity in the treatment of internal derangement of TMJ. PURPOSE: The aim of this study was to compare between the effect of arthrocentesis and intra-articular injection using a mixture of hyaluronic acid and corticosteroid in the management of TMJ internal derangement. MATERIALS AND METHODS: Sixteen patients with TMJ internal derangement were selected and divided into 2 equal groups. In group I, arthrocentesis was performed with Ringer solution. In group II, intra-articular injection was performed with a mixture of 0.5ml hyaluronic acid and 0.5ml corticosteroid. Assessment of pain, maximum mouth opening, lateral movement and clicking was done before the treatment, one week, one month and three months after the treatment. All parameters were subjected to statistical analysis. RESULTS: All studied parameters showed improvements. There was no statistically significant difference between the two groups regarding intensity of pain, maximum mouth opening, lateral movement and joint sound. CONCLUSIONS: TMJ arthrocentesis and intra-articular injection of a mixture of hyaluronic acid and corticosteroid have been found to be effective for treatment of TMJ internal derangement with reduction. Nevertheless, the simplicity of intra articular injection makes it the treatment of choice.

Reliability of diffusion-weighted magnetic resonance imaging in differentiation of recurrent cholesteatoma and granulation tissue after intact canal wall mastoidectomy.

OBJECTIVE: To assess the reliability of diffusion-weighted magnetic resonance imaging in differentiating recurrent cholesteatoma from granulation tissue after intact canal wall mastoidectomy. METHODS: A prospective study was conducted of 56 consecutive patients with suspected cholesteatoma recurrence after intact canal wall mastoidectomy who underwent diffusion-weighted imaging and delayed contrast magnetic resonance imaging of the temporal bone. The final diagnosis was recurrence in 38 patients and granulation tissue in 18 patients. RESULTS: Cholesteatoma detection on diffusion-weighted imaging based on two sets of readings had sensitivity of 94.7 and 94.7 per cent, specificity of 94.4 and 88.9 per cent, and accuracy of 94.6 and 92.8 per cent, with good intra-observer agreement (Κ = 0.72, p = 0.001). Cholesteatoma detection on delayed contrast magnetic resonance imaging had sensitivity of 81.6 and 78.9 per cent, specificity of 77.8 and 66.7 per cent, and accuracy of 80.4 and 75.0 per cent, with fair intra-observer agreement (Κ = 0.57, p = 0.001). The mean cholesteatoma diameter on diffusion-weighted imaging was 7.7 ± 1.8 and 7.9 ± 1.8 mm, with excellent intra-observer agreement (Κ = 0.994, p = 0.001). CONCLUSION: Diffusion-weighted imaging is a reliable method for differentiating recurrent cholesteatoma and granulation tissue after intact canal wall mastoidectomy.

Correlation of apparent diffusion coefficient with histopathological parameters of salivary gland cancer.

The aim of this study was to correlate the apparent diffusion coefficient (ADC) with histopathological parameters of salivary gland cancer. A retrospective analysis of 44 patients with salivary gland cancer who underwent diffusion-weighted magnetic resonance imaging of salivary glands was performed. The ADC of salivary gland cancer was correlated with pathological tumour type and grade, stage (T stage and N stage), and morphological (perineural spread and location) prognostic parameters. There was a significant difference in ADC values between low-intermediate- and high-grade tumours (P = 0.024), lower T stages (T1, T2) versus higher T stages (T3, T4) (P = 0.001), lower N stages (N0, N1) versus higher N stages (N2, N3) (P = 0.001), and the presence versus absence of perineural spread (P = 0.001). The cut-off ADC values to predict higher-grade, higher T stage, nodal spread, and perineural spread were 0.94, 0.92, 0.94, and 0.98 × 10-3 mm2/s, with area under the curve of 0.847, 0.858, 0.900, and 0.798 and accuracy of 75.0%, 75.0%, 75.0%, and 77.3%, respectively. The ADC value is a non-invasive imaging parameter that correlates with histopathological parameters of salivary gland cancer.

Arterial spin labelling and diffusion-weighted magnetic resonance imaging in differentiation of recurrent head and neck cancer from post-radiation changes.

OBJECTIVE: To assess arterial spin labelling and diffusion-weighted imaging in the differentiation of recurrent head and neck cancer from post-radiation changes. METHODS: A retrospective study was conducted of 47 patients with head and neck cancer, treated with radiotherapy, who underwent magnetic resonance arterial spin labelling and diffusion-weighted magnetic resonance imaging. Tumour blood flow and apparent diffusion co-efficient of the lesion were calculated. RESULTS: There was significant difference (p = 0.001) in tumour blood flow between patients with recurrent head and neck cancer (n = 31) (47.37 ± 16.3 ml/100 g/minute) and those with post-radiation changes (n = 16) (18.80 ± 2.9 ml/100 g/minute). The thresholds of tumour blood flow and apparent diffusion co-efficient used for differentiating recurrence from post-radiation changes were more than 24.0 ml/100 g/minute and 1.21 × 10-3 mm2/second or less, with area under the curve values of 0.94 and 0.90, and accuracy rates of 88.2 per cent and 88.2 per cent, respectively. The combined tumour blood flow and apparent diffusion co-efficient values used for differentiating recurrence from post-radiation changes had an area under the curve of 0.96 and an accuracy of 90.2 per cent. CONCLUSION: Combined tumour blood flow and apparent diffusion co-efficient can differentiate recurrence from post-radiation changes.

Assessment of solid lesions of the temporal fossa with diffusion-weighted magnetic resonance imaging.

The aim of this work was to assess solid lesions of the temporal fossa with diffusion-weighted magnetic resonance imaging (MRI). A retrospective analysis of diffusion-weighted MRI obtained for 33 patients with solid lesions of the temporal fossa was conducted. Fifteen of the patients were male and 18 were female, and their mean age was 39 years. The apparent diffusion coefficient (ADC) of solid lesions of the temporal fossa was calculated on two separate occasions by the same observer. The mean ADC values (×10(-3)mm(2)/s) of the two readings in cases of malignancy (0.98±0.17 and 0.95±0.13) were significantly different to those of benign lesions (1.32±0.24 and 1.28±0.21) (P=0.001 and 0.001), with excellent intra-observer agreement (κ=0.937). The area under the receiver operating characteristic curve was 0.855. A threshold ADC of 1.23×10(-3)mm(2)/s was found to have an accuracy of 91%, with sensitivity of 94% and specificity of 85%, for differentiating malignancy of the temporal fossa from benign lesions. It is concluded that ADC is a non-invasive imaging parameter that is able to differentiate malignancy of the temporal fossa from benign lesions.

Role of computed tomography angiography in the diagnosis of vascular stenosis in head and neck microvascular free flap reconstruction.

The aim of this study was to evaluate the role of computed tomography angiography (CTA) in the diagnosis of vascular stenosis at the vascular pedicle of head and neck microvascular free flaps. A prospective study was done of 65 consecutive patients (49 male, 16 female; mean age 55 years) who had undergone head and neck microvascular free flap reconstruction. All patients underwent 64-slice CTA of the carotid artery. Post-processing with volume rendering reconstruction of CTA images was done. There was excellent inter-observer agreement (weighted kappa=0.82, 95% confidence interval (CI) 0.74-0.93) in grading of the degree of vascular stenosis. The true sensitivity of CTA for diagnosis of stenosis of the vascular pedicle to the flap was 63% (95% CI 63-100%). Patients with failed flaps showed complete occlusion (n=2) on CTA and underwent a replacement flap procedure. Patients with failing flaps showed severe stenosis (n=6) of the vascular pedicle on CTA and underwent revision surgery. There was no change in the degree of stenosis on follow-up CTA for patients with moderate stenosis (n=9). CTA is a reliable, non-invasive, high-quality imaging tool for the diagnosis and grading of vascular stenosis of the vascular pedicle of head and neck microvascular free flaps.

Role of diffusion-weighted MRI in differentiation of masticator space malignancy from infection.

OBJECTIVE: The aim of this study was to assess the role of the apparent diffusion coefficient (ADC) value in differentiation of masticator space malignancy from infection. METHODS: A retrospective study of 49 patients (31 male and 18 female; age range 5-66 years) with masticator space lesion was conducted. They underwent spin-echo-type echo planar diffusion-weighted MRI of the head and neck with b-values of 0 mm(2) s(-1), 500 mm(2) s(-1) and 1000 mm(2) s(-1). The ADC maps were reconstructed and the ADC value of the masticator space lesion was calculated. RESULTS: The mean (± standard deviation) ADC value of masticator space malignancy (0.91 ± 0.21 × 10(-3) mm(2) s(-1)) was significantly lower (p = 0.001) than that of masticator space infection (1.59 ± 0.32 × 10(-3) mm(2) s(-1)). When an ADC value of 1.20 × 10(-3) mm(2) s(-1) was used as a threshold value for differentiating masticator space malignancy from infection, the best result was obtained with an accuracy of 88%, sensitivity of 88%, specificity of 87%, negative predictive value of 94%, positive predictive value of 86% and area under the curve of 0.92. There was a significant difference in the ADC value between squamous cell carcinoma and soft tissue sarcoma (p = 0.001), as well as between bacterial and fungal infection of the masticator space (p = 0.001). CONCLUSION: We concluded that ADC value is a non-invasive promising imaging parameter that can be used for differentiation of masticator space malignancy from infection.

Results of prosthetic mesh repair in the emergency management of the acutely incarcerated and/or strangulated ventral hernias: a seven years study.

PURPOSE: The aim of this prospective study was to present a 7-year experience with the use of prosthetic mesh repair in the management of the acutely incarcerated and/or strangulated ventral hernias. METHODS: Patients with acutely incarcerated and/or strangulated ventral hernias were treated by emergency repair of the hernia using an onlay Prolene mesh. The presence of non-viable intestine necessitating resection-anastomosis of the bowel was not considered a contraindication to the use of mesh. RESULTS: The present study included 80 patients. Their age ranged from 25 to 86 years with a mean of 56.1 ± 13.2 years. The hernia was para-umbilical in 71 patients (88.75 %), epigastric in 6 patients (7.5 %) and incisional in 3 patients (3.75 %). Eighteen patients (22.5 %) had recurrent hernias. Resection-anastomosis of non-viable small intestine was performed in 18 patients (22.5 %). There were 2 perioperative mortalities (2.5 %). Complications were encountered in 17 patients (21.3 %) and included wound sepsis in 9 patients (11.25 %), seroma formation in 5 patients (6.25 %), chest infection in 4 patients (5 %), deep vein thrombosis in 1 patient (1.25 %) and mesh infection in another patient (1.25 %). Follow-up duration ranged from 12 to 84 months with a mean of 49.9 ± 19.9 months. Only one recurrence was encountered throughout the study period. CONCLUSIONS: The use of prosthetic mesh repair in the emergency management of the acutely incarcerated and/or strangulated ventral hernias is safe. The presence of non-viable intestine cannot be regarded as a contraindication for prosthetic repair.

Imaging of scleroma in the head and neck.

We review the appearance of scleroma in the head and neck on imaging. Scleroma is a chronic granulomatous disease that primarily affects the nasal cavity, but the pharynx and larynx may also be involved. On imaging, nasal scleroma appears as bilateral or unilateral expanded homogeneous nasal masses that may exhibit hyperintense signal on T(1) weighted images. Pharyngeal scleroma commonly narrows the pharyngeal lumen and may involve the soft and hard palate. Imaging is essential to detect the extent of subglottic stenosis in patients with laryngeal scleroma. Rarely, scleroma may involve the orbit or the middle ear. Imaging is essential for the early diagnosis of scleroma and for differentiating it from other granulomatous and neoplastic lesions. Also, imaging is important for treatment planning and follow-up of patients after therapy.

Correlation of apparent diffusion coefficient at 3T with prognostic parameters of retinoblastoma.

BACKGROUND AND PURPOSE: Pathologic prognostic parameters for retinoblastoma have been defined. Our purpose was to correlate ADC values at 3T with prognostic parameters of retinoblastoma. MATERIALS AND METHODS: This study included 72 children (30 boys and 42 girls, mean age 19 ± 2.6 months) with retinoblastoma. Pretreatment diffusion-weighted MR imaging was performed on a 3T scanner with b factors of 0, 500, and 1000 seconds/mm(2). ADC values were calculated and pathologic specimens were analyzed. ADC values of the tumors were then correlated with prognostic parameters, including degree of histologic differentiation, tumor size, bilaterality, choroidal invasion, and optic nerve extension. RESULTS: The mean ADC value of retinoblastoma was 0.49 ± 0.12 × 10(-3) mm(2)/s. The ADC values of well- and moderately differentiated tumors were significantly different (P = .007) from poorly and undifferentiated retinoblastoma. There was also a significant difference in the ADC value among small, medium, and large tumors (P = .015), as well as between unilateral and bilateral retinoblastoma (P = .001), and this was independent of the degree of differentiation. The ADC value was also significantly lower (P = .003) when optic nerve invasion was present. There was no correlation of ADC value with growth pattern or choroidal invasion (P = .640 and 0.661, respectively). The ADC value of retinoblastoma was well correlated with the degree of differentiation of the tumor (r = 0.87, P = .007) and inversely correlated with the size of the tumor (r = -0.68, P = .015). CONCLUSIONS: ADC correlated with some of the accepted parameters of poor prognosis for retinoblastoma and may serve as a noninvasive prognostic parameter for assessment of newly diagnosed retinoblastoma.

Clinical, hematological, and biochemical findings of uterine torsion in buffaloes (Bubalus bubalis).

The aim of this study was to investigate uterine torsion in buffaloes, examine factors influencing the outcome of the disease, and to characterize the related alterations in blood constituents. A total of 126 buffaloes with uterine torsion were examined for stage of gestation, duration, degree, site and direction of torsion, as well as the location of the pregnant horn. Methods of correction were documented along with dam and calf survival. Blood samples were obtained from 20 buffaloes with uterine torsion and 10 healthy buffaloes for hematological and biochemical comparisons. Results showed that uterine torsion in buffaloes occurred in multi- (81.7%) and primiparous (18.3%), during late pregnancy (58.4%) and at full term (41.6%), clockwise (96%) and counter- clockwise (4%), at post- (98.4%) and precervical (1.6%), and was of high (52.3%), moderate (31%) and mild (16.7%) degrees. Torsion was predominantly (P=0.01) on same direction of the pregnant horn. Fetal and maternal mortalities occurred in 78.6% and 23.8% of the cases, respectively. The stage of pregnancy, and degree and duration of uterine torsion were major risk factors for fetal mortality (P=0.0001), while the stage of pregnancy and fetal viability were important risk factors for maternal mortality (P<0.05). There were significant (P<0.05) increases in monocytes, albumin, aspartate aminotransferase, creatine phosphokinase, blood urea nitrogen, and phosphorus and decreases in mean corpuscular hemoglobin concentration and globulin in the affected buffaloes. Time of occurrence and duration of torsion affected some of these parameters. Uterine torsion appears to be a serious problem in buffaloes that has certain peculiarities including time of occurrence, site and direction of torsion, and the high mortality rates. Uterine torsion adversely affects liver and kidney functions. Multiparous might be at greater risk of uterine torsion. The stage of pregnancy, as well as degree and duration of uterine torsion are risk factors for fetal and maternal mortalities.

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 14-68 years, mean age 39 years) with skull-base lesions. Diffusion-weighted MR images were acquired with a b-factor of 500 and 1,000 s/mm(2) 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) mm(2)/s and that of benign tumours was (1.63 ± 0.29) × 10(-3) mm(2)/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(-3)mm(2)/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.

Imaging appearance of primary bony tumors and pseudo-tumors of the spine.

We aim to review the imaging appearance of primary bony tumors of the spine and simulating lesions. Benign bone tumors commonly appear as well-circumscribed, slow-growing lesions with a calcified or sclerotic matrix. Malignancy is often aggressive permeative lesions with bone destruction, cortical invasion and associated soft-tissue mass. CT is an excellent imaging modality for characterization of the tumor matrix, exact location, extension and osseous changes, while MR imaging is superior for evaluation of the associated soft-tissue mass, bone marrow infiltration and intraspinal extension. There is a spectrum of pseudotumors that may also involve the spine. The imaging appearance of primary spinal bone tumor in conjunction with the patient's age, gender and lesion location allows a high percentage of correct diagnosis. Imaging plays an important role in diagnosis, characterization and extension of bone tumors of the spine which will help guide therapy.

Magnetic resonance appearance of cerebral cystic echinococcosis: World Health Organization (WHO) classification.

BACKGROUND: Cystic echinococcosis (CE) of the brain is an uncommon parasitic infestation. The World Health Organization (WHO) recently published a classification of hepatic CE based upon ultrasonographic findings. PURPOSE: To evaluate whether the new WHO classification of hepatic CE can be used in the classification of cerebral CE. MATERIAL AND METHODS: The magnetic resonance (MR) imaging findings of 17 patients (14 male, three female), aged 10-24 years (mean age 16 years), with pathologically proved cerebral CE, and who underwent pre- and postcontrast MR imaging, were retrospectively evaluated. The cysts were classified according to the new WHO classification and their clinical stages. The MR imaging findings were correlated to the histopathologic findings. RESULTS: The fertile active cysts (n=12) that showed protoscoleces appeared as unilocular cysts with no visible wall (cystic lesions; CL), unilocular spherical cysts with a clear visible wall (CE1), or as a unilocular mother cyst with multiple vesicles arranged peripherally along the cyst wall (CE2). The transitional form (CE3) (n=2) containing scoleces showed multiple daughter cysts entirely filling the maternal cyst. The inactive cysts (n=3) that had lost their fertility appeared as a "ball of wool" with collapsed membrane or had detached membrane with water-lily sign (CE4) and calcified lesions (CE5). CONCLUSION: The WHO classification of hepatic CE can be used in the classification of cerebral CE when evaluated by MRI, as it can differentiate fertile active cysts from the transitional and inactive forms of cerebral cystic echinococcosis. This information is essential for treatment planning.