Magnetic resonance imaging (MRI) offers outstanding soft tissue contrast that may reduce uncertainties in target and organ-at-risk delineation and enable online adaptive image-guided treatment. ...Spatial distortions resulting from non-linearities in the gradient fields and non-uniformity in the main magnetic field must be accounted for across the imaging field-of-view to prevent systematic errors during treatment delivery. This work presents a modular phantom and software application to characterize geometric distortion (GD) within the large field-of-view MRI images required for radiation therapy simulation. The modular phantom is assembled from a series of rectangular foam blocks containing high-contrast fiducial markers in a known configuration. The modular phantom design facilitates transportation of the phantom between different MR scanners and MR-guided linear accelerators and allows the phantom to be adapted to fit different sized bores or coils. The phantom was evaluated using a 1.5 T MR-guided linear accelerator (MR-Linac) and 1.5 T and 3.0 T diagnostic scanners. Performance was assessed by varying acquisition parameters to induce image distortions in a known manner. Imaging was performed using T1 and T2 weighted pulse sequences with 2D and 3D distortion correction algorithms and the receiver bandwidth (BW) varied as 250-815 Hz pixel
. Phantom set-up reproducibility was evaluated across independent set-ups. The software was validated by comparison with a non-modular phantom. Average geometric distortion was 0.94 ± 0.58 mm for the MR-Linac, 0.90 ± 0.53 mm for the 1.5 T scanner, and 1.15 ± 0.62 mm for the 3.0 T scanner, for a 400 mm diameter volume-of-interest. GD increased, as expected, with decreasing BW, and with the 2D versus 3D correction algorithm. Differences in GD attributed to phantom set-up were 0.13 mm or less. Differences in GD for the two software applications were less than 0.07 mm. A novel modular phantom was developed to evaluate distortions in MR images for radiation therapy applications.
Background Neurolymphomatosis involving the cranial nerves (CNs) is rare. We sought a better understanding of the primary disease sites and patterns of spread in neurolymphomatosis of the orbit and ...retro-orbital cranial nerves. Methods Patients with lymphoma and MRI evidence of neurolymphomatosis of CN II, III, IV, V.sub.1, or V.sub.2 were retrospectively reviewed. Demographics and primary disease site and sites of neurolymphomatosis on MRI were recorded. Wilcoxon rank sum test was used to compare number of sites of neurolymphomatosis with lymphoma type and survival. Results The study included 18 patients. The most frequent types of lymphoma were diffuse large B-cell (DLBCL) (n = 9) and marginal zone (n = 3). In 9 patients, lymphoma presented as a mass (n = 7) or infiltrative disease (n = 2) directly involving the orbit; in 6, a maxillofacial mass spread directly to CNs; and in 3, lymphoma at remote sites spread to orbital CNs. Overall, 81 sites of neurolymphomatosis were noted. The most common sites were the maxillary nerve (V.sub.2) including at the infraorbital fissure or foramen rotundum (17 patients; 19 nerves), pterygopalatine fossa (16 patients; 19 nerves), and cavernous sinus (9 patients; 12 nerves). Number of sites of neurolymphomatosis was significantly lower for DLBCL than for other lymphoma types (p = 0.007). Number of sites of neurolymphomatosis did not affect survival (p = 0.26). The mean interval between the pathologic diagnosis and MRI documentation of the full extent of neurolymphomatosis was 39 days after pathologic diagnosis. Conclusions Based on our study results, neurolymphomatosis in the orbit appears to be frequently associated with an orbital and/or maxillofacial mass and commonly involves CN V.sub.2, the pterygopalatine fossa, and the cavernous sinus. DLBCL may be associated with fewer sites of neurolymphomatosis than other lymphomas. In patients with lymphoma, a systematic search for neurolymphomatosis is imperative for early detection. Keywords: Neurolymphomatosis, Lymphoma, Cranial nerves, Orbits
Cross-sectional imaging plays an important role in the evaluation of the retropharyngeal space (RPS) and the prevertebral space (PVS). Because of their deep location within the neck, lesions arising ...within these spaces are difficult, if not impossible, to evaluate on clinical examination. This article details the cross-sectional anatomy and imaging appearances of primary and secondary diseases involving the RPS and PVS, including metastasis and spread from adjacent spaces. The role of image-guided biopsy is also discussed.
To review the clinical presentation, treatment, and prognosis of patients with malignant mixed tumor (carcinoma ex pleomorphic adenoma) of the lacrimal gland.
Clinical records and radiographic images ...were reviewed for patients with malignant mixed tumor of the lacrimal gland treated at the center during 2008-2019.
The study included 9 patients (6 men, 3 women) aged 17-66 years (median age, 56 years). Six had primary malignant mixed tumor with no history of orbital lesions, and 3 had previously been diagnosed with pleomorphic adenoma. Tumor, Node, Metastasis classification per the eighth edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual were T1aN0M0 in 2 patients, T2aN0M0 in 3 patients, T4bN0M0 in 2 patients, and T4cN0M0 in 2 patients. Two patients underwent orbital exenteration, 6 patients underwent eye-sparing surgery, and 1 patient had an unresectable tumor because of cavernous sinus extension. All patients received radiotherapy (intensity-modulated radiotherapy in 3 and proton therapy in 6). All patients received chemotherapy, 8 concurrently with radiotherapy and 1 after radiotherapy. The median follow-up time was 70 months. At last contact, 6 patients were alive without evidence of disease; 2 had died of disease, 1 of distant metastasis, and the other of cavernous sinus invasion.
The findings suggest that de novo malignant mixed tumor of the lacrimal gland is more common than disease that results from transformation after incomplete resection of lacrimal gland pleomorphic adenoma. Most cases can be treated with eye-sparing surgery and radiation unless skull base extension is present.
To evaluate the frequency and clinical course of residual orbital masses on imaging studies after multimodality treatment for orbital rhabdomyosarcoma.
Retrospective case series.
We reviewed records ...of patients with primary orbital rhabdomyosarcoma who underwent chemotherapy and radiotherapy after surgical biopsy or debulking at 4 US centers during 1998-2019. Demographics, histologic subtype, tumor response 12 weeks after chemotherapy initiation and after completion of all treatment, and imaging findings were analyzed.
Thirty-two patients met inclusion criteria. Twenty-two were male, and 30 were younger than 18 years. Histologic subtype was embryonal in 22 patients, alveolar in 8, and mixed embryonal/alveolar in 2. Median follow-up time was 46 months (range, 4.9-199 months). Two patients died. Twenty-seven patients had reliable end-of-treatment imaging findings, of whom 9 had a residual mass. Three residual masses disappeared spontaneously (by 4, 32, and 53 months), 2 remained at last contact, at 2 and 7 years of follow-up, and 3 were excised; 1 progressed and underwent an exenteration. Complete response at 12 weeks was associated with complete response at the end of treatment (P < .001). Patients with T1 or T2 tumor at presentation were more likely to have complete response at last contact than were those with T3 or T4 tumor (P < .05). Biopsy type (incisional or excisional) was not associated with response to treatment at any time point.
A residual orbital mass on imaging may be present after multimodality treatment in approximately one-third of patients. Resolution without biopsy or excision varied from months to years.
Background
Thyroglossal duct cysts (TGDCs) are the most common congenital midline cystic lesions in the neck, and they are often evaluated by fine‐needle aspiration. Recognizing the cytomorphologic ...features of TGDCs and their mimics is important for clinical management.
Methods
This study examined the clinical, radiological, and cytopathological features of 86 ultrasonography‐guided fine‐needle aspiration (US‐FNA) specimens from clinically suspected TGDCs or malignancies arising from TGDCs and correlated the findings with surgical follow‐up and/or imaging studies.
Results
According to ultrasound examinations of 66 lesions, 17 (25.8%) were cystic, 8 (12.1%) were cystic with septations, 21 (31.8%) were cystic with solid nodules, and 20 (30.3%) were solid or cystic with internal debris. Cytopathologically, 81 lesions (94%) were categorized as benign, 2 (2%) were categorized as atypical, and 3 (3%) were categorized as malignant. In benign lesions, proteinaceous material (63%), histiocytes (63%), colloid (37%), squamous cells (35%), columnar cells (32%), follicular cells (15%), inflammatory cells (9%), and multinucleated giant cells (9%) were noted. Diagnoses in the benign category included TGDC in 64 patients (75%), TGDC or mimics (colloid nodule/epidermoid cyst) in 14 patients (17%), a colloid nodule in 1 patient, and thyroiditis in 1 patient. Surgical resection, performed in 23 patients, confirmed TGDCs in 12, benign mimics in 7, and carcinoma in 4.
Conclusions
Cytopathological features, in conjunction with imaging, allowed a definite diagnosis of TGDC in most patients (75%). The presence of mature squamous cells, thyroid follicular cells, with or without colloid and/or lymphocytes alone allowed a differential diagnosis of TGDC and its mimics in 17%. US‐FNA findings could not distinguish primary carcinomas arising from TGDCs from metastatic tumors.
Cytopathological features, in conjunction with clinical and imaging findings, can be useful for the diagnosis of the majority but not all cases of thyroglossal duct cysts with ultrasound‐guided fine‐needle aspiration specimens. The distinction of primary neoplasms arising from the cysts from metastatic tumors is not possible with these specimens.
Background
To describe the clinical presentation, treatment, and overall prognosis in eight patients with primary Ewing's sarcoma (ES) involving the orbit.
Methods
A retrospective interventional ...study of all biopsy‐proven cases of primary ES involving the orbit was done.
Results
There were seven males and one female with a median age of 14 years. Imaging showed osseous involvement in all eight cases with extraorbital extension in four. Complete tumor resection was done in four, partial resection in three, and biopsy followed by sinus surgery in one. EWSR1 gene rearrangement analysis was done to confirm diagnosis. All patients received multidrug systemic chemotherapy and seven patients received adjuvant radiotherapy. Eye salvage was achieved in all patients. At a mean follow‐up duration of 52.63 months, seven patients were doing well with no evidence of disease.
Conclusions
ES involving the orbit is sensitive to chemotherapy and radiation. Aggressive multimodality treatment can help salvage the globe and improve overall survival.
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