Is a Close Follow-Up Computed Tomography Necessary for Acute Falcine and Tentorial Subdural Hematoma?

OBJECTIVE: This study aimed to assess the changes and values on follow-up computed tomography (F/U-CT) for isolated falcine (F-SDH) and tentorial (T-SDH) subdural hematomas (SDHs). METHOD: Fifty-four cases of isolated F-SDH and/or T-SDH were retrospectively reviewed. Subdural hematoma morphology, mass effect on the adjacent parenchyma, and interval change at F/U-CT were evaluated. Subdural hematoma size was measured parallel and perpendicular to the falx/tentorium (long or short axis, respectively). RESULTS: Short-axis increase on F/U-CT was seen only in 5 F-SDHs (16%) and 7 T-SDHs (19%), with a maximum of a 2-mm increase. Long-axis growth was more prominent and frequent, seen in 18 F-SDH patients (56.2%) and 19 T-SDH patients (51.4%), with maximum change of up to 43 mm. Falcine SDH and T-SDH were ipsilateral and contiguous in 77.8% of patients. Minimal mass effect was seen in 13 patients (24.1%), which was resolved or stable on F/U-CT. Anticoagulation did not affect SDH size. No patients required neurosurgery or died. CONCLUSIONS: Based on our limited data, the current standard of F/U-CT may be unnecessary in patients with isolated F-SDH and/or T-SDH, which expand minimally along the short axis without a significant mass effect. Characteristic anatomic structure of the tentorium and falx, and their connectivity may direct SDH expansion and limit mass effect as well as injury to the adjacent parenchyma.

Tumor radiomic heterogeneity: Multiparametric functional imaging to characterize variability and predict response following cervical cancer radiation therapy.

BACKGROUND: Robust approaches to quantify tumor heterogeneity are needed to provide early decision support for precise individualized therapy. PURPOSE: To conduct a technical exploration of longitudinal changes in tumor heterogeneity patterns on dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) and FDG positron emission tomography / computed tomography (PET/CT), and their association to radiation therapy (RT) response in cervical cancer. STUDY TYPE: Prospective observational study with longitudinal MRI and PET/CT pre-RT, early-RT (2 weeks), and mid-RT (5 weeks). POPULATION: Twenty-one FIGO IB2 -IVA cervical cancer patients receiving definitive external beam RT and brachytherapy. FIELD STRENGTH/SEQUENCE: 1.5T, precontrast axial T1 -weighted, axial and sagittal T2 -weighted, sagittal DWI (multi-b values), sagittal DCE MRI (<10 sec temporal resolution), postcontrast axial T1 -weighted. ASSESSMENT: Response assessment 1 month after completion of treatment by a board-certified radiation oncologist from manually delineated tumor volume changes. STATISTICAL TESTS: Intensity histogram (IH) quantiles (DCE SI10% and DWI ADC10% , FDG-PET SUVmax ) and distribution moments (mean, variance, skewness, kurtosis) were extracted. Differences in IH features between timepoints and modalities were evaluated by Skillings-Mack tests with Holm's correction. Area under receiver-operating characteristic curve (AUC) and Mann-Whitney testing was performed to discriminate treatment response using IH features. RESULTS: Tumor IH means and quantiles varied significantly during RT (SUVmean : ↓28-47%, SUVmax : ↓30-59%, SImean : ↑8-30%, SI10% : ↑8-19%, ADCmean : ↑16%, P < 0.02 for each). Among IH heterogeneity features, FDG-PET SUVCoV (↓16-30%, P = 0.011) and DW-MRI ADCskewness decreased (P = 0.001). FDG-PET SUVCoV was higher than DCE-MRI SICoV and DW-MRI ADCCoV at baseline (P < 0.001) and 2 weeks (P = 0.010). FDG-PET SUVkurtosis was lower than DCE-MRI SIkurtosis and DW-MRI ADCkurtosis at baseline (P = 0.001). Some IH features appeared to associate with favorable tumor response, including large early RT changes in DW-MRI ADCskewness (AUC = 0.86). DATA CONCLUSION: Preliminary findings show tumor heterogeneity was variable between patients, modalities, and timepoints. Radiomic assessment of changing tumor heterogeneity has the potential to personalize treatment and power outcome prediction. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1388-1396.

Intravoxel incoherent motion MRI assessment of chemoradiation-induced pelvic bone marrow changes in cervical cancer and correlation with hematological toxicity.

PURPOSE: To investigate bone marrow changes after chemoradiation (CRT) using intravoxel incoherent motion magnetic resonance imaging (IVIM-MRI) and correlate imaging changes with hematological toxicity (HT) in patients with locally advanced cervical cancer. MATERIALS AND METHODS: Thirty-nine patients with newly diagnosed cervical cancer were prospectively recruited for two sequential 3.0T IVIM-MRI studies: before treatment (MRI-1) and 3-4 weeks after standardized CRT (MRI-2). The irradiated pelvic bone marrow was outlined as the regions of interest to derive the true diffusion coefficient (D) and perfusion fraction (f) based on a biexponential model. The apparent coefficient diffusion (ADC) was derived using the monoexponential model. Changes in these parameters between MRI-1 and MRI-2 were calculated as ΔD, Δf, and ΔADC. HT was defined accordingly to NCI-CTCAE (v. 4.03) of grade 3 and above. Statistical analysis was performed using Mann-Whitney U-test. RESULTS: The median age of patients was 54 years old (range 27-83 years old); 14 patients suffered from HT. Early bone marrow changes (3-4 weeks) of ΔD showed a significant difference between HT and non-HT groups (6.4 ± 19.7% vs. -6.4 ± 19.4%, respectively, P = 0.041). However, no significant changes were noted in Δf (3.7 ± 13.3% vs. 1.5 ± 12.5% respectively, P = 0. 592) and ΔADC (5.5 ± 26.3% vs. -3.3 ± 27.0% respectively, P = 0.303) between the HT and non-HT groups. Δf increased insignificantly for both groups. CONCLUSION: ΔD was the only significant parameter to differentiate early cellular environment changes in bone marrow after CRT, suggestive that ΔD was more sensitive than Δf and ΔADC to reflect the underlying microenvironment injury. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1491-1498.

Revisiting Current Golden Rules in Managing Acute Ischemic Stroke: Evaluation of New Strategies to Further Improve Treatment Selection and Outcome.

OBJECTIVE: Advanced stroke imaging has generated much excitement for the early diagnosis of acute ischemic stroke (AIS) and facilitation of intervention. However, its therapeutic impact has not matched its diagnostic utility; most notably, lacking significant contributions to recent major AIS clinical trials. It is time to reexamine the fundamental hypotheses from the enormous body of imaging research on which clinical practices are based and reassess the current standard clinical and imaging strategies, or golden rules, established over decades for AIS. In this article, we will investigate a possible new window of opportunity in managing AIS through a better understanding of the following: first, the potential limitations of the golden rules; second, the significance of imaging-based parenchymal hypoperfusion (i.e., lower-than-normal relative cerebral blood flow [rCBF] may not be indicative of ischemia); third, the other critical factors (e.g., rCBF, collateral circulation, variable therapeutic window, chronicity of occlusion) that reflect more individual ischemic injury for optimal treatment selection; and, fourth, the need for penumbra validation in successfully reperfused patients (not in untreated patients). CONCLUSION: Individual variations in the therapeutic window, ischemic injury (rCBF), and chronicity of vascular lesion development have not been comprehensively incorporated in the standard algorithms used to manage AIS. The current established imaging parameters have not been consistently validated with successfully reperfused patients and rCBF to quantitatively distinguish between oligemia and ischemia and between penumbra and infarct core within ischemic tissue. A novel paradigm incorporating rCBF values or indirectly incorporating relative rCBF values with higher statistically powered imaging studies to more reliably assess the severity of ischemic injury and differentiate reversibility from viability within the area of imaging-based parenchymal hypoperfusion may provide a more personalized approach to treatment, including no treatment of infarction core, to further enhance outcomes.

Imaging across the life span: innovations in imaging and therapy for gynecologic cancer.

The focus of this article is radiation therapy for gynecologic cancers, with emphasis on imaging-based treatment planning and delivery. For the various gynecologic cancers, radiation oncologists rely on essential clinical information to triage treatment options, and various imaging studies are performed for treatment planning and radiation therapy delivery. A practical approach is provided to help radiologists tailor their reports for the needs of their radiation oncology and gynecologic oncology colleagues, to optimize multidisciplinary care for patients with gynecologic cancer. Template radiology reports are proposed to address the specific information needs of oncologists at each phase-before, during, and after treatment. Fueled by the rapid progress in engineering and computer sciences during the past 2 decades, remarkable advances have been made in anatomic, functional, and molecular imaging and in radiation treatment planning and delivery in patients with gynecologic cancer. Radiation therapy has evolved from a nontargeted approach to a precisely targeted, highly conformal treatment modality, to further improve treatment outcomes and reduce morbidity. High-quality imaging has become essential for staging of the disease, delineation of tumor extent for treatment planning and delivery, and monitoring therapy response. Anatomic and functional imaging has also been shown to provide prognostic information that allows clinicians to tailor therapy on the basis of personalized patient information. This field is an area of active research, and future clinical trials are warranted to validate preliminary results in the field.

Understanding patient satisfaction ratings for radiology services.

OBJECTIVE: Under the Hospital Value-Based Purchasing Program of the Centers for Medicare & Medicaid Services, patient satisfaction accounts for 30% of the measures of and payments for quality of care. Understanding what drives patient satisfaction data and how the data are obtained, converted into scores, and formulated into rankings is increasingly critical for imaging departments. The objectives of this article are to describe the potential impact of patient satisfaction ratings on institutions and individuals, explain how patient satisfaction is rated and ranked, identify drivers that affect the ratings and rankings, and probe the resulting challenges unique to radiology departments. CONCLUSION: Research results indicate that training providers to make simple modifications in their language and behavior during patient care can significantly impact patient satisfaction, which, in turn, can impact both quality-of-care ratings and the bottom line of hospitals. Training providers is a simple and cost-effective way to potentiate the clinical expression of compassion into improvement of patient satisfaction and financial reward, a national trend that no one in the game can afford to ignore.

Unusual motion detected on real-time sonography inside a glomus tumor in the thigh.

Glomus tumors are rare and many have been reported to have a hypervascular appearance on color or power Doppler sonography. We report a pathologically proven case of superficial glomus tumor within the thigh with no detectable color flow signals on color or power Doppler sonography. In addition, real-time sonography showed spontaneous motions within the tumor, which were not synchronized with vascular or respiratory motions, and misled the presurgical diagnosis of a suspected parasite in a patient who had direct contact with multiple animal species. The etiology of this internal motion remains hypothetical but, if reconfirmed, this finding may be a useful adjunctive sign for the diagnosis of glomus tumors.

"Tumoral pseudoblush" identified within gliomas at high-spatial-resolution ultrahigh-field-strength gradient-echo MR imaging corresponds to microvascularity at stereotactic biopsy.

PURPOSE: To use directed biopsy sampling to determine whether microvascular assessment within gliomas, by means of ultrahigh-field-strength high-spatial-resolution gradient-echo (GRE) magnetic resonance (MR) imaging at 8 T, correlates with histopathologic assessment of microvascularity. MATERIALS AND METHODS: The study was institutional review board approved and HIPAA compliant. Informed consent was obtained. Thirty-five subjects with gliomas underwent 8-T and 80-cm MR imaging by using a GRE sequence (repetition time, 600-750 msec; echo time, 10 msec; in-plane resolution, 196 mm). Haphazardly arranged serpentine low-signal-intensity structures, often associated with areas of low signal intensity within the tumor bed ("tumoral pseudoblush") at MR imaging, were presumed to be related to tumoral microvascularity. Microvessel density (MVD) and microvessel size (MVS) ranked with a semiquantitative three-tier scale (high, medium, and low) relative to cortical penetrating veins were assessed from regions of interest identified at MR imaging and were compared with a similar assessment of stereotactic biopsy specimens by using Kendall τb. Tumor grade (high vs low) was compared with ultrahigh-field-strength high-resolution GRE MR analysis by using Pearson χ2. Discrepancies between 8-T and histopathologic assessment were identified and analyzed. RESULTS: Ultrahigh-field-strength high-resolution GRE MR imaging and histopathologic assessment concurred for MVS (P<.0001) and MVD (P<.0001). World Health Organization classification tumor grade was associated with number (P<.0005) and size (P<.0005) of foci of microvascularity within the tumor bed at 8-T MR imaging. Radiation-induced microvessel hyalinosis mimicked tumor microvascularity at 8-T MR imaging. Potential confounders could result from radiofrequency inhomogeneity and displaced normal microvasculature. CONCLUSION: Microvascularity identified as a tumoral pseudoblush at ultrahigh-field-strength high-resolution GRE MR imaging without contrast material shows promise as a marker for increased tumoral microvascularity.

A generalized linear-quadratic model incorporating reciprocal time pattern of radiation damage repair.

PURPOSE: It has been conventionally assumed that the repair rate for sublethal damage (SLD) remains constant during the entire radiation course. However, increasing evidence from animal studies suggest that this may not the case. Rather, it appears that the repair rate for radiation-induced SLD slows down with increasing time. Such a slowdown in repair would suggest that the exponential repair pattern would not necessarily accurately predict repair process. As a result, the purpose of this study was to investigate a new generalized linear-quadratic (LQ) model incorporating a repair pattern with reciprocal time. The new formulas were tested with published experimental data. METHODS: The LQ model has been widely used in radiation therapy, and the parameter G in the surviving fraction represents the repair process of sublethal damage with T(r) as the repair half-time. When a reciprocal pattern of repair process was adopted, a closed form of G was derived analytically for arbitrary radiation schemes. The published animal data adopted to test the reciprocal formulas. RESULTS: A generalized LQ model to describe the repair process in a reciprocal pattern was obtained. Subsequently, formulas for special cases were derived from this general form. The reciprocal model showed a better fit to the animal data than the exponential model, particularly for the ED50 data (reduced χ(2) (min) of 2.0 vs 4.3, p = 0.11 vs 0.006), with the following gLQ parameters: α/ß = 2.6-4.8 Gy, T(r) = 3.2-3.9 h for rat feet skin, and α/ß = 0.9 Gy, T(r) = 1.1 h for rat spinal cord. CONCLUSIONS: These results of repair process following a reciprocal time suggest that the generalized LQ model incorporating the reciprocal time of sublethal damage repair shows a better fit than the exponential repair model. These formulas can be used to analyze the experimental and clinical data, where a slowing-down repair process appears during the course of radiation therapy.

Whole-Lesion DCE-MRI Intensity Histogram Analysis for Diagnosis in Patients with Suspected Lung Cancer.

RATIONALE AND OBJECTIVES: To explore the diagnostic value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) intensity histogram metrics, relative to time intensity curve (TIC)-derived metrics, in patients with suspected lung cancer. MATERIALS AND METHODS: This retrospective study enrolled 49 patients with suspected lung cancer on routine CT imaging who underwent DCE-MRI scans and had final histopathologic diagnosis. Three TIC-derived metrics (maximum enhancement ratio, peak time [Tmax] and slope) and eight intensity histogram metrics (volume, integral, maximum, minimum, median, coefficient of variation [CoV], skewness, and kurtosis) were extracted from DCE-MRI images. TIC-derived and intensity histogram metrics were compared between benignity versus malignancy using the Wilcoxon rank-sum test. Associations between imaging metrics and malignancy risk were assessed by univariate and multivariate logistic regression odds ratios (ORs). RESULTS: There were 33 malignant lesions and 16 benign lesions based on histopathology. Lower CoV (OR = 0.2 per 1-SD increase, p = 0.0006), lower Tmax (OR = 0.4 per 1-SD increase, p = 0.005), and steeper slope (OR = 2.4 per 1-SD increase, p = 0.010) were significantly associated with increased risk of malignancy. Under multivariate analysis, CoV was significantly independently associated with malignancy likelihood after accounting for either Tmax (OR = 0.3 per 1-SD increase, p = 0.007) or slope (OR = 0.3 per 1-SD increase, p = 0.011). CONCLUSION: This initial study found that DCE-MRI CoV was independently associated with malignancy in patients with suspected lung cancer. CoV has the potential to help diagnose indeterminate pulmonary lesions and may complement TIC-derived DCE-MRI metrics. Further studies are warranted to validate the diagnostic value of DCE-MRI intensity histogram analysis.

Temporal analysis of tumor heterogeneity and volume for cervical cancer treatment outcome prediction: preliminary evaluation.

In this paper, we present a method of quantifying the heterogeneity of cervical cancer tumors for use in radiation treatment outcome prediction. Features based on the distribution of masked wavelet decomposition coefficients in the tumor region of interest (ROI) of temporal dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) studies were used along with the imaged tumor volume to assess the response of the tumors to treatment. The wavelet decomposition combined with ROI masking was used to extract local intensity variations in the tumor. The developed method was tested on a data set consisting of 23 patients with advanced cervical cancer who underwent radiation therapy; 18 of these patients had local control of the tumor, and five had local recurrence. Each patient participated in two DCE-MRI studies: one prior to treatment and another early into treatment (2-4 weeks). An outcome of local control or local recurrence of the tumor was assigned to each patient based on a posttherapy follow-up at least 2 years after the end of treatment. Three different supervised classifiers were trained on combinational subsets of the full wavelet and volume feature set. The best-performing linear discriminant analysis (LDA) and support vector machine (SVM) classifiers each had mean prediction accuracies of 95.7%, with the LDA classifier being more sensitive (100% vs. 80%) and the SVM classifier being more specific (100% vs. 94.4%) in those cases. The K-nearest neighbor classifier performed the best out of all three classifiers, having multiple feature sets that were used to achieve 100% prediction accuracy. The use of distribution measures of the masked wavelet coefficients as features resulted in much better predictive performance than those of previous approaches based on tumor intensity values and their distributions or tumor volume alone.

The Dancing Cord: Inherent Spinal Cord Motion and Its Effect on Cord Dose in Spine Stereotactic Body Radiation Therapy.

BACKGROUND: Spinal cord dose limits are critically important for the safe practice of spine stereotactic body radiotherapy (SBRT). However, the effect of inherent spinal cord motion on cord dose in SBRT is unknown. OBJECTIVE: To assess the effects of cord motion on spinal cord dose in SBRT. METHODS: Dynamic balanced fast field echo (BFFE) magnetic resonance imaging (MRI) was obtained in 21 spine metastasis patients treated with SBRT. Planning computed tomography (CT), conventional static T2-weighted MRI, BFFE MRI, and dose planning data were coregistered. Spinal cord from the dynamic BFFE images (corddyn) was compared with the T2-weighted MRI (cordstat) to analyze motion of corddyn beyond the cordstat (Dice coefficient, Jaccard index), and beyond cordstat with added planning organ at risk volume (PRV) margins. Cord dose was compared between cordstat, and corddyn (Wilcoxon signed-rank test). RESULTS: Dice coefficient (0.70-0.95, median 0.87) and Jaccard index (0.54-0.90, median 0.77) demonstrated motion of corddyn beyond cordstat. In 62% of the patients (13/21), the dose to corddyn exceeded that of cordstat by 0.6% to 13.8% (median 4.3%). The corddyn spatially excursed outside the 1-mm PRV margin of cordstat in 9 patients (43%); among these dose to corddyn exceeded dose to cordstat >+ 1-mm PRV margin in 78% of the patients (7/9). Corddyn did not excurse outside the 1.5-mm or 2-mm PRV cord cordstat margin. CONCLUSION: Spinal cord motion may contribute to increases in radiation dose to the cord from SBRT for spine metastasis. A PRV margin of at least 1.5 to 2 mm surrounding the cord should be strongly considered to account for inherent spinal cord motion.

Neuroimaging for Radiation Therapy of Brain Tumors.

Delineating the gross tumor volume (GTV) is a core task within radiation treatment planning. GTVs must be precisely defined irrespective of the region involved, but even more so in a sensitive area such as the brain. As precision medicine cannot exist without precision imaging, the current article aims to discuss the various imaging modalities employed in the radiation treatment planning of brain tumors.Gliomas, meningiomas, and paragangliomas are some of the most challenging tumors and the advancement in diagnostic imaging can significantly contribute to their delineation. For gliomas, irradiation based on multiparametric magnetic resonance imaging (MRI) and amino-acid positron emission tomography (PET)/computed tomography (CT) may have a higher sensitivity and specificity, which could lead to a better sparing of organs at risk and help distinguish between tumor, edema, and radiogenic alterations. Meningiomas and paragangliomas are often associated with a good prognosis. Therefore, GTV delineation according to MRI and somatostatin receptor ligand-PET/CT plays an essential role in sparing sensitive structures and maintaining a good quality of life for these patients.The combination of multiparametric MRI and PET/CT (possibly in the form of PET/MRI) presently appears to be the optimal approach for target volume delineation. The comparative efficacy of these imaging modalities has to be further evaluated in prospective trials.

Diffusion-weighted MRI and ADC versus FET-PET and GdT1w-MRI for gross tumor volume (GTV) delineation in re-irradiation of recurrent glioblastoma.

BACKGROUND AND PURPOSE: GTV definition for re-irradiation treatment planning in recurrent glioblastoma (rGBM) is usually based on contrast-enhanced MRI (GdT1w-MRI) and, for an increased specificity, on amino acid PET. Diffusion-weighted (DWI) MRI and ADC maps can reveal regions of high cellularity as surrogate for active tumor. The objective of this study was to compare the localization and quality of diffusion restriction foci (GTV-ADClow) with FET-PET (GTV-PET) and GdT1w-MRI (GTV-GdT1w-MRI). MATERIAL AND METHODS: We prospectively evaluated 41 patients, who received a fractionated stereotactic re-irradiation for rGBM. GTV-PET was generated automatically (tumor-to-background ratio 1.7-1.8) and manually customized. GTV-ADClow was manually defined based on DWI data (3D diffusion gradients, b = 0, 1000 s/mm2) and parametric ADC maps. The localization of recurrence was correlated with initial GdT1w-MRI and PET data. RESULTS: In 30/41 patients, DWI-MRI showed areas with restricted diffusion (mean ADC-value 0.74 ±â€¯0.22 mm2/s). 66% of GTVs-ADClow were located outside the GdT1w-MRI volume and 76% outside increased FET uptake regions. Furthermore, GTVs-ADClow were only partially included in the high dose volume and received in mean 82% of the reference dose. An adjusted volume including GdT1w-MRI, PET-positive and restricted diffusion areas would imply a GTV increase of 48%. GTV-PET and GdT1w-MRI correlated better with the localization of re-recurrence in comparison to GTV-ADClow. CONCLUSION: Unexpectedly, GTV-ADClow overlapped only partially with FET-PET and GdT1w-MRI in rGBM. Moreover, GTV-ADClow correlated poorly with later rGBM-recurrences. Seeing as a restricted diffusion is known to correlate with hypercellularity, this imaging discrepancy could only be further explained in histopathological studies.

Strategies to Mitigate Toxicities From Stereotactic Body Radiation Therapy for Spine Metastases.

Improvements in systemic therapy are translating into more patients living longer with metastatic disease. Bone is the most common site of metastasis, where spinal lesions can result in significant pain impacting quality of life and possible neurological dysfunction resulting in a decline in performance status. Stereotactic body radiation therapy (SBRT) of the spine has emerged as a promising technique to provide durable local control, palliation of symptoms, control of oligoprogressive sites of disease, and possibly augment the immune response. SBRT achieves this by delivering highly conformal radiation therapy to allow for dose escalation due to a steep dose gradient from the planning target volume to nearby critical organs at risk. In our review, we provide an in-depth review and expert commentary regarding seminal literature that defined clinically meaningful toxicity endpoints with actionable dosimetric limits and/or clinical management strategies to mitigate toxicity potentially attributable to SBRT of the spine. We placed a spotlight on radiation myelopathy (de novo, reirradiation after conventional external beam radiation therapy or salvage after an initial course of spinal SBRT), plexopathy, vertebral compression fracture, pain flare, esophageal toxicity, myositis, and safety regarding combination with concurrent targeted or immune therapies.

Hypofractionation regimens for stereotactic radiotherapy for large brain tumors.

PURPOSE: To investigate equivalent regimens for hypofractionated stereotactic radiotherapy (HSRT) for brain tumor treatment and to provide dose-escalation guidance to maximize the tumor control within the normal brain tolerance. METHODS AND MATERIALS: The linear-quadratic model, including the effect of nonuniform dose distributions, was used to evaluate the HSRT regimens. The alpha/beta ratio was estimated using the Gammaknife stereotactic radiosurgery (GKSRS) and whole-brain radiotherapy experience for large brain tumors. The HSRT regimens were derived using two methods: (1) an equivalent tumor control approach, which matches the whole-brain radiotherapy experience for many fractions and merges it with the GKSRS data for few fractions; and (2) a normal-tissue tolerance approach, which takes advantages of the dose conformity and fractionation of HSRT to approach the maximal dose tolerance of the normal brain. RESULTS: A plausible alpha/beta ratio of 12 Gy for brain tumor and a volume parameter n of 0.23 for normal brain were derived from the GKSRS and whole-brain radiotherapy data. The HSRT prescription regimens for the isoeffect of tumor irradiation were calculated. The normal-brain equivalent uniform dose decreased as the number of fractions increased, because of the advantage of fractionation. The regimens for potential dose escalation of HSRT within the limits of normal-brain tolerance were derived. CONCLUSIONS: The designed hypofractionated regimens could be used as a preliminary guide for HSRT dose prescription for large brain tumors to mimic the GKSRS experience and for dose escalation trials. Clinical studies are necessary to further tune the model parameters and validate these regimens.

Serial therapy-induced changes in tumor shape in cervical cancer and their impact on assessing tumor volume and treatment response.

OBJECTIVE: The purpose of this study was to evaluate the patterns and distribution of tumor shape and its temporal change during radiation therapy (RT) in cervical cancer and the effect of tumor configuration changes on the correlation between region of interest (ROI)-based and diameter-based MRI tumor measurement. MATERIALS AND METHODS: Serial MRI examinations (T1-weighted and T2-weighted images) were performed in 60 patients (age range, 29-75 years; mean, 53.3 years) with advanced cervical cancer (stages IB2-IVB/recurrent) who were treated with RT at four time points: start of RT, during RT (at 2-2.5 and at 4-5 weeks of RT), and post-RT. Tumor configuration was classified qualitatively into oval, lobulated, and complex based on MR film review. Two methods of tumor volume measurement were compared: ellipsoid computation of three orthogonal diameters (diameter based) and ROI volumetry by delineating the entire tumor volume on the MR workstation (ROI based). Temporal changes of tumor shape and the respective tumor volumes measured by the two methods were analyzed using linear regression analysis. RESULTS: Most tumors (70%) had a non-oval (lobulated and complex) shape before RT and became increasingly irregular during and after RT: 84% at 2-2.5 weeks of RT (p = 0.037), 86% (p = 0.025) at 4-5 weeks, and 96% post-RT (p = 0.010), compared with 70% pre-RT. Diameter-based and ROI-based measurement correlated well before RT (r = 0.89) but not during RT (r = 0.68 at 2-2.5 weeks, r = 0.67 at 4-5 weeks of RT). CONCLUSION: Most cervical cancers are not oval in shape pretherapy, and they become increasingly irregular during and after therapy because of nonconcentric tumor shrinkage. ROI-based volumetry, which can optimally measure irregular volumes, may provide better response assessment during treatment than diameter-based measurement.

Clinical magnetic resonance imaging of brain tumors at ultrahigh field: a state-of-the-art review.

With the advancement of the magnetic resonance (MR) technology, the whole-body ultrahigh field MR system operated from 7 to 9.4 T becomes feasible for the routine patient imaging in clinical settings. The associated potentials and challenges from the perspectives of technology, physics, and biology as well as clinical application of the ultrahigh field MR systems are different from those systems operated at 3 T, 1.5 T, or lower field strength. In this article, we will present our initial experiences of brain tumor imaging using the 7 and 8 T whole-body MR systems at the Ohio State University Medical Center and provide a brief overview pertinent to the ultrahigh field clinical MR systems.

Contrast-enhanced magnetic resonance imaging of central nervous system tumors: agents, mechanisms, and applications.

Brain tumors are one of the most common neoplasms in young adults and are associated with a high mortality and disability rate. Magnetic resonance imaging (MRI) is widely accepted to be the most sensitive imaging modality in the assessment of cerebral neoplasms. Because the detection, characterization, and exact delineation of brain tumors require a high lesion contrast that depends on the signal of the lesion in relation to the surrounding tissue, contrast media is given routinely. Anatomical and functional, contrast agent-based MRI techniques allow for a better differential diagnosis, grading, and especially therapy decision, planing, and follow-up. In this article, the basics of contrast enhancement of brain tumors will be reviewed. The underlying pathology of a disrupted blood-brain barrier and drug influences will be discussed. An overview of the currently available contrast media and the influences of dosage, field strength, and application on the tumor tissue contrast will be given. Challenging, contrast-enhanced, functional imaging techniques, such as perfusion MRI and dynamic contrast-enhanced MRI, are presented both from the technical side and the clinical experience in the assessment of brain tumors. The advantages over conventional, anatomical MRI techniques will be discussed as well as possible pitfalls and drawbacks.

Cranial nerve involvement in nasopharyngeal carcinoma: response to radiotherapy and its clinical impact.

OBJECTIVES: To evaluate the cranial nerve (CN) palsy associated with nasopharyngeal carcinoma (NPC), we studied factors that influenced the neurologic outcome of radiotherapy (RT), and the patterns and time course of neurologic recovery of CN palsy. METHODS: Between July 1987 and July 1989, 93 patients who presented with CN palsy at the time of diagnosis of NPC were studied. All patients underwent external-beam RT with either cobalt-60 or 6-MV photon beams to a dose of 69 to 84 Gy at 2 Gy per fraction. The time course and pattern of neurologic recovery (complete, partial, or none) from CN palsy were evaluated. Age, sex, stage, histology, incidence and distribution of types of CNs involved, duration of CN palsy, and time course of tumor response during RT were correlated with the patterns and the time course of neurologic CN recovery by univariate and multivariate analyses. RESULTS: The cases of CN palsy most commonly involved CN V (38%), CN VI (26%), and CN XII (11%), which accounted for the majority of the cases (75%). The time course of CN recovery was variable and protracted. Most patients showed significant improvement upon completion of RT (51%, 19%, and 30% complete, partial, and no recovery, respectively) and further improvement 6 months after RT (58%, 17%, and 25%, respectively). Cranial nerves V, VI, and XII accounted for 75% of cases with no recovery. Recovery was best for CNs II, IX, and XI and the sympathetic nerve (100%, 87%, 100%, and 100%, respectively) and worst for CNs IV, VII, and XII (67%, 60%, and 40%, respectively, with no recovery). Neurologic CN recovery correlated significantly with the pretherapy duration (<3 months versus > or =3 months) of CN palsy (88% versus 62%; p = .002, multivariate analysis), the time course of clinical tumor regression, and neurologic symptom improvement during RT. Age, sex, T stage, N stage, histology, anterior versus posterior CN palsies, and base of skull involvement were not significant. CONCLUSIONS: According to our limited data, most patients with CN palsy respond well to RT. That the time course of neurologic recovery is variable and can be protracted indicates a need for continuous and close neurologic surveillance. The poorer neurologic outcome associated with a longer duration of CN symptoms may be related to a more severe longterm CN compression that results in irreversible damage. Timely diagnosis of NPC and fast institution of therapy are therefore critical to improving the neurologic outcome.