High-dose planned adaptive helical tomotherapy for cutaneous angiosarcoma of the scalp.

PURPOSE: The purpose of this study was to investigate the feasibility and effectiveness of high-dose planned adaptive intensity-modulated radiation therapy (IMRT) with helical tomotherapy (HT) for cutaneous angiosarcoma (cAS) of the scalp. METHODS: This retrospective cross-sectional included a total of 12 consecutive patients with cAS of the scalp who underwent high-dose planned adaptive IMRT with HT. Prescribed doses were 72.5-74 Gy in 35-37 fractions for the gross tumor volume plus a 1-2 mm margin (PTV1), 58-60 Gy in 29-30 fractions for the clinical target volume plus a 2-3 mm margin (PTV2), and 46 Gy in 23 fractions for the clinical target volume plus a 5-15 mm margin (PTV3) over periods of 7.5, 6 and 4.5 weeks, respectively. RESULTS: The estimated 1­year and 2­year overall survival rate were 65.6% and 27.3%, respectively, and the local progression-free survival at 2 years was 74.1%. All local recurrences were either in or marginal to the PTV2 or PTV3. No local recurrence was observed in the PTV1. All patients tolerated the treatment without grade 3 or higher adverse events during the radiotherapy period. No late adverse events were observed during the follow-up period. CONCLUSION: Planned adaptive high-dose IMRT with HT has the potential to improve local control rate without increasing adverse events.

MRI findings of iatrogenic extravasation of gadolinium-based contrast agents in patients with cancer.

BACKGROUND: Magnetic resonance imaging (MRI) findings after subcutaneous extravasation of gadolinium-based contrast agent (GBCA) have not been investigated in detail. PURPOSE: To present the MRI findings of iatrogenic extravasation and to evaluate the characteristic findings. MATERIAL AND METHODS: In this retrospective study of 16,039 patients with cancer, 11 patients had significant extravasation of macrocyclic GBCA, and 7 of the 11 had MRI of the injection site. Characteristic MRI findings as well as symptoms and changes over time were evaluated. RESULTS: The forearms or antecubital fossa felt cold in all seven cases, and 3 (43%) patients felt pain at the injection sites. Fat-suppressed T1-weighted images showed a mosaic pattern of the extravasate with mixed high and low signal in the subcutaneous tissue in 7 (100%) cases. Contrast enhancement of the fascia toward the proximal portion was observed in 3 (43%) cases. There was no subfascial deep extension. On T2-weighted images, GBCAs were observed as low-signal fluid collection on the fascia, with linear spread to the dermis and subcutaneous tissue. Four patients underwent daily MRI scans, all of whom had their contrast disappeared within three days. CONCLUSION: Macrocyclic GBCA disappears from subcutaneous tissue quickly after extravasation and is unlikely to cause serious sequelae.

High-Dose Planned Adaptive Intensity-Modulated Radiation Therapy with Simultaneous Integrated Boost for Synchronous Oligometastatic Pancreatic Cancer.

The purpose of this study was to investigate the efficacy and feasibility of high-dose (72.6 Gy) planned adaptive intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) for 9 consecutive patients with synchronous oligometastatic pancreatic ductal adenocarcinoma (PDAC). The estimated 2-year overall survival rate was 66.7%, and the local progression-free survival at 2 years was 83.3%. No severe adverse events were observed. Planned adaptive dose-escalated IMRT-SIB has the potential to improve local control rate and prolong overall survival in patients with synchronous oligometastatic PDAC.

Long-term follow-up results of endorectal balloon-assisted helical tomotherapy for localized prostate cancer patients in the high-risk group of gastrointestinal adverse events.

Background: Endorectal balloon (ERB) has been shown to reduce rectal radiation dose and late gastrointestinal toxicities in patients with prostate cancer. However, the usefulness of ERBs for patients with prostate cancer whose rectal shape or size is suboptimal has not been investigated. The purpose of this study was to present the long-term follow-up results of ERB-assisted helical tomotherapy for localized prostate cancer patients whose initial radiation treatment planning (RTP) was unacceptable due to suboptimal rectal shape or size. Materials and methods: Of 541 consecutive patients with localized prostate cancer, 10 were included in this study whose RTPs without ERBs did not meet dose constraints due to: 1) Intestinal intrusion, 2) Small rectum; or 3) Unstable rectal shape. We re-planned using ERBs and delivered 76 Gy in 38 fractions, and evaluated the long-term usefulness and safety of ERB-assisted helical tomotherapy. Results: At a median follow-up of 109 months, there were no local recurrences of prostate cancer. The overall, cause-specific, and progression-free survivals at 10 years were 90.0%, 100%, and 83%, respectively. Adverse events of grade 3 or higher were not observed during or after ERB-assisted helical tomotherapy. Conclusions: When intestinal intrusion, a small rectum, or an unstable rectal shape is an obstacle for administering helical tomotherapy, ERBs might be the solution.

Superparamagnetic iron oxide-enhanced MRI-guided stereotactic ablative radiation therapy for liver metastasis.

BACKGROUND: MRI-guided radiation therapy can image a target and irradiate it at the same time. Superparamagnetic iron oxide (SPIO) is a liver-specific contrast agent that can selectively visualize liver tumors, even if plain MRI does not depict them. The purpose of this study was to present a proof of concept of SPIO-enhanced MRI-guided radiation therapy for liver tumor. CASE PRESENTATION: MRI-guided stereotactic ablative radiation therapy (SABR) was planned for a patient with impaired renal function who developed liver metastases after nephroureterectomy for ureteral cancer. Because liver metastasis was not visualized on plain MRI, SPIO-enhanced MRI was performed at 0.35 T using true fast imaging with steady-state free precession (true FISP) pulse sequence and SABR was performed. Liver metastasis was clearly visualized by SPIO-enhanced MRI, and MRI-guided SABR was performed without adverse events. CONCLUSION: Even if liver metastasis is not visualized by plain MRI, liver metastasis can be clearly depicted by administering SPIO, and MRI-guided radiation therapy can be performed.

Dual-Energy Spectral CT: Various Clinical Vascular Applications.

Single-source dual-energy (DE) computed tomography (CT) with fast switching of tube voltage allows projection-based image reconstruction, substantial reduction of beam-hardening effects, reconstruction of accurate monochromatic images and material decomposition images (MDIs), and detailing of material composition by using x-ray spectral information. In vascular applications, DE CT is expected to overcome limitations of standard single-energy CT angiography, including patient exposure to nephrotoxic contrast medium and carcinogenic radiation, insufficient contrast vascular enhancement, interference from metallic and beam-hardening artifacts and severe vessel calcification, and limited tissue characterization and perfusion assessment. Acquisition of low-energy monochromatic images and iodine/water MDIs can reasonably reduce contrast agent dose and improve vessel enhancement. Acquisition of virtual noncontrast images, such as water/iodine MDIs, can reduce overall radiation exposure by replacing true noncontrast CT in each examination. Acquisition of monochromatic images by using metal artifact reduction software or acquisition of iodine/water MDIs can reduce metal artifacts with preserved or increased vessel contrast, and subtraction of monochromatic images between two energy levels can subtract coils composed of dense metallic materials. Acquisition of iodine/calcium (ie, hydroxyapatite) MDIs permits subtraction of vessel calcification and improves vessel lumen delineation. Sensitive detection of lipid-rich plaque can be achieved by using fat/water MDIs, the spectral Hounsfield unit curve (energy level vs CT attenuation), and a histogram of effective atomic numbers included in an image. Various MDIs are useful for accurate differentiation among materials with high attenuation values, including contrast medium, calcification, and fresh hematoma. Iodine/water MDIs are used to assess organ perfusion, such as in the lungs and myocardium. Understanding these DE CT techniques enhances the value of CT for vascular applications. (©)RSNA, 2016.

Whole-Body Clinical Applications of Digital Tomosynthesis.

With flat-panel detector mammography, radiography, and fluoroscopy systems, digital tomosynthesis (DT) has been recently introduced as an advanced clinical application that removes overlying structures, enhances local tissue separation, and provides depth information about structures of interest by providing high-quality tomographic images. DT images are generated from projection image data, typically using filtered back-projection or iterative reconstruction. These low-dose x-ray projection images are easily and swiftly acquired over a range of angles during a single linear or arc sweep of the x-ray tube assembly. DT is advantageous in a variety of clinical contexts, including breast, chest, head and neck, orthopedic, emergency, and abdominal imaging. Specifically, compared with conventional mammography, radiography, and fluoroscopy, as a result of reduced tissue overlap DT can improve detection of breast cancer, pulmonary nodules, sinonasal mucosal thickening, and bone fractures and delineation of complex anatomic structures such as the ostiomeatal unit, atlantoaxial joint, carpal and tarsal bones, and pancreatobiliary and gastrointestinal tracts. Compared with computed tomography, DT offers reduced radiation exposure, better in-plane resolution to improve assessment of fine bony changes, and less metallic artifact, improving postoperative evaluation of patients with metallic prostheses and osteosynthesis materials. With more flexible patient positioning, DT is also useful for functional, weight-bearing, and stress tests. To optimize patient management, a comprehensive understanding of the clinical applications and limitations of whole-body DT applications is important for improvement of diagnostic quality, workflow, and cost-effectiveness. Online supplemental material is available for this article. (©)RSNA, 2016.

Current and Novel Imaging Techniques in Coronary CT.

Multidetector coronary computed tomography (CT), which is widely performed to assess coronary artery disease noninvasively and accurately, provides excellent image quality. Use of electrocardiography (ECG)-controlled tube current modulation and low tube voltage can reduce patient exposure to nephrotoxic contrast media and carcinogenic radiation when using standard coronary CT with a retrospective ECG-gated helical scan. Various imaging techniques are expected to overcome the limitations of standard coronary CT, which also include insufficient spatial and temporal resolution, beam-hardening artifacts, limited coronary plaque characterization, and an inability to allow functional assessment of coronary stenosis. Use of a step-and-shoot scan, iterative reconstruction, and a high-pitch dual-source helical scan can further reduce radiation dose. Dual-energy CT can improve contrast medium enhancement and reasonably reduce the contrast dose when combined with noise reduction with the use of iterative reconstruction. High-definition CT can improve spatial resolution and diagnostic evaluation of small or peripheral coronary vessels and coronary stents. Dual-source CT and a motion correction algorithm can improve temporal resolution and reduce coronary motion artifacts. Whole-heart coverage with 320-detector CT and an intelligent boundary registration algorithm can eliminate stair-step artifacts. By decreasing beam hardening and enabling material decomposition, dual-energy CT is expected to remove or reduce the depiction of coronary calcification to improve intraluminal evaluation of calcified vessels and to provide detailed analysis of coronary plaque components and accurate qualitative and quantitative assessment of myocardial perfusion. Fractional flow reserve derived from coronary CT is a state-of-the-art noninvasive technique for accurately identifying myocardial ischemia beyond coronary CT. Understanding these techniques is important to enhance the value of coronary CT for assessment of coronary artery disease.

The Effects of Boron Neutron Capture Therapy on the Lungs in Recurrent Breast Cancer Treatment.

Boron neutron capture therapy (BNCT) has predominantly been performed for brain tumors or head and neck cancers. Although BNCT is known to be applicable to breast cancer, it has only been performed in a few cases involving thoracic region irradiation with reactor-based BNCT systems. Thus, there are very few reports on the effects of BNCT on the thoracic region and no reports of BNCT for breast cancer with accelerator-based BNCT systems. This paper introduces the world's first clinical study employing an accelerator-based BNCT system targeting recurrent breast cancer after radiation therapy. We aim to assess the efficacy and safety of BNCT, focusing on the dose response in the thoracic region, especially concerning the potential for radiation pneumonitis. Preliminary findings from the first three cases indicate no evidence of radiation pneumonitis within three months post treatment. This study not only establishes a foundation for novel breast cancer treatment options but also contributes significantly to the field of BNCT in the thoracic region.

Multiparametric MRI-guided Hypofractionated Intensity-modulated Radiation Therapy With Simultaneous Integrated Boost for Glioblastoma.

BACKGROUND/AIM: This study investigated the feasibility and efficacy of multiparametric magnetic resonance imaging (MRI)-guided dose-escalated hypofractionated intensity-modulated radiation therapy with simultaneous integrated boost (IMRT-SIB) for glioblastoma. PATIENTS AND METHODS: Eighteen patients underwent postoperative IMRT-SIB for glioblastoma using three MRI sequences: double inversion recovery (DIR), diffusion tensor imaging (DTI), and post-gadolinium T1-weighted imaging. Prescribed doses were 60 Gy and 40 Gy in 15 fractions for residual enhancing lesions and surrounding tumor-infiltrating areas, respectively. For surrounding tumor-infiltrating areas, asymmetric margins were set with reference to DTI imaging. RESULTS: The 1-year overall survival rate was 58.0%, and the 1-year local control rate for the residual enhancing lesions was 76.2%, while that for surrounding tumor-infiltrating areas was 39.4%. One patient (6%) developed grade 2 cerebral radiation necrosis 10 months after IMRT-SIB, but there was no grade 3 or higher adverse event. CONCLUSION: Multiparametric MRI-guided dose-escalated IMRT-SIB with DIR and DTI imaging has the potential to improve local control rates without increasing adverse events.

SPIO-enhanced 0.35T MRI-guided radiotherapy for liver malignancies: usefulness in tumor visualization.

OBJECTIVES: The purpose of this study was to investigate the changes of tumor-to-liver signal ratio in a 0.35T MRI-guided radiotherapy system and to evaluate the usefulness and pitfalls of superparamagnetic iron oxide (SPIO) administration for visualization of liver tumors. METHODS: Forty-two patients treated with MRI-guided stereotactic ablative radiotherapy (SABR) for liver tumors were included in this study. The tumor-to-liver signal ratios before and after SPIO administration were retrospectively assessed and compared on true fast imaging with steady-state precession (FISP). RESULTS: Before SPIO administration, liver tumors were either invisible or barely visible in 15 cases (36%), but all tumors became visible after SPIO administration. The mean values of tumor-to-liver signal ratio before and after SPIO administration were 0.939 ± 0.201 and 1.336 ± 0.300, respectively (mean ± standard deviation, p < 0.001). In six (14%) patients, liver tumors were visible on true FISP imaging before SPIO administration, but became invisible after administration. CONCLUSIONS: This study showed that liver tumors that are invisible on true FISP imaging can be made visible by administration of SPIO, and that MRI-guided SABR can be performed accurately. ADVANCES IN KNOWLEDGE: This is the first report to examine the usefulness of liver-specific contrast agent superparamagnetic iron oxides in 0.35T MRI-guided radiation therapy. Liver tumors that are invisible on true fast imaging with steady-state precession can be made visible by administration of superparamagnetic iron oxides.

MRI-guided stereotactic ablative radiation therapy for liver metastasis from pancreatic cancer.

A 69-year-old man with a history of pancreatic cancer was referred to our hospital for a newly developed solitary liver metastasis. Since the liver metastasis was in contact with the small intestine, it was necessary to perform radiation therapy while simultaneously monitoring the small intestine and liver metastasis, and then, MRI-guided stereotactic ablative radiation therapy (SABR) was performed. There were no radiation-induced adverse events during the treatment and 6 months of follow-up. MRI showed complete regression of the tumor at 6 months after SABR. It seems feasible to perform SABR safely by using MRI-guided radiation therapy system even if liver metastasis developed near the intestinal tract after surgery for pancreatic cancer.

Quantitative evaluation of volume change of perirectal hydrogel spacer by Dixon-based water-only images.

Purpose: There are no detailed data on volume changes of SpaceOAR hydrogel spacer. The purpose of this study was to quantitatively evaluate the volume changes of SpaceOAR during radiation therapy for prostate cancer. Materials: The volume of SpaceOAR in seven prostate cancer patients was quantitatively measured every two weeks by Dixon-based water-only MRI scans. Results: The volume of SpaceOAR increased and remained increased for 11 weeks after placement in all cases. The day to reach the maximum volume was 49.9 +/- 9.2 (mean +/- standard deviation [SD]) days after placement. The maximum rate of increase in Space OAR volume was 20% +/- 9% (mean +/- SD). Conclusions: The volume of SpaceOAR was shown to be greater than the initial volume for 11 weeks after placement, with an increase of up to 20%. Therefore, care should be taken when creating a radiation treatment planning and positioning a patient during radiation therapy.

Tomotherapy: Comparison of Hi-ART, Tomo-HD, and Radixact.

Aim In this study, we compared three generations of tomotherapy (Hi-ART, Tomo-HD, and Radixact). This is to study the difference among tomotherapy systems in terms of dose distribution to planning target volume and organs at risk, and irradiation time.  Materials and methods The treatment planning CT and contour information used were seven cases of rectum cancer pre-operative irradiation. The contour information used was the planning target volume, and the organs at risk were set as the bladder and body. Optimization was conducted at each planning station using the parameters that were actually used in a clinical setting. The prescribed radiation dose was 25 Gy in five fractions and normalized at the isodose line, covering 95% of the planning target volume. Results There were no significant differences in planning target volume among the three models. Meanwhile, Hi-ART had a significantly higher dose than Tomo-HD and Radixact at body D50%. Radixact shortened the irradiation time by approximately 15% compared to Hi-ART/Tomo-HD. Conclusion Planning target volume dose distribution of tomotherapy devices was not different. Radixact required a significantly shorter time than Hi-ART and Tomo-HD.

Comparison of gross tumor volumes of pulmonary metastasis defined by CT and MRI in 0.345 T MRI-guided radiotherapy.

OBJECTIVE: To assess the difference in gross tumor volumes (GTVs) defined by CT (GTV-CT) and by low magnetic field strength (0.345 T) MRI (GTV-MRI) in patients simulated for MRI-guided radiotherapy forlung metastasis. METHODS: 28 patients (148 lesions) who underwent CT and MRI simulation with the tri-60Co MRI-guided radiotherapy system (MRIdian, ViewRay) were included in this study. GTV-CT and GTV-MRI were compared using the paired t-test. The equivalence of variance between GTV-CT and GTV-MRI of small lesions (GTV-CT <1 ml) and large ones (GTV-CT >= 1 ml) was evaluated using F-test. The correlation between GTV-CT and GTV-MRI was evaluated by the correlation coefficient. RESULTS: GTV-MRI was 120% larger than GTV-CT (p < 0.001) for small lesions, whereas GTV-MRI was 40% larger than GTV-CT (p < 0.001) for large lesions. In small lesions, the variation in GTV-MRI was significantly larger than that of GTV-CT (p < 0.001). There was no significant difference in the variation of GTV-MRI and GTV-CT in large lesions (p = 0.121). The correlation coefficient for small lesions was 0.93, whereas that for large lesions was 0.99, with large lesions having better correlation. CONCLUSIONS: GTV-MRI was larger than GTV-CT and the correlation between GTV-MRI and GTV-CT was better in large lesions. If the tumor volume is 1 ml or larger, the lesion can be accurately monitored even with a low magnetic field strength MRI. ADVANCES IN KNOWLEDGE: This study is the first clinical report to evaluate the tolerability of MRI images in 0.345 T MRI-guided radiotherapy for lung metastasis. GTV contoured by MRI was larger than GTV by CT, and this tendency was more pronounced in small tumors of less than 1 ml.

Pancytopenia due to massive bone marrow carcinomatosis after radiotherapy for locally advanced breast cancer.

Pancytopenia is a rare complication among patients with breast cancer. Here, we report a case of pancytopenia due to massive bone marrow carcinomatosis (BMC) developed after local radiotherapy following to mastectomy. A 48-year-old woman with locally advanced breast cancer underwent mastectomy and axillary lymph node dissection. During adjuvant chemotherapy, rapidly growing supraclavicular lymph node metastasis was noted, so chemotherapy was discontinued and local radiotherapy was performed. There was no myelosuppression or systemic metastases prior to radiotherapy, but 2 weeks after the completion of radiotherapy, complete blood counts showed pancytopenia, and chest CT scans revealed multiple bone metastasis. A bone marrow biopsy was performed and massive BMC was diagnosed. Despite the best supportive care, her disease progressed rapidly and she died 2 months after radiotherapy. Locally advanced breast cancer that is resistant to chemotherapy is at risk of early fatal BMC and should be carefully monitored.

Influence of the motion correction algorithm on the quality and interpretability of images of single-source 64-detector coronary CT angiography among patients grouped by heart rate.

PURPOSE: We retrospectively investigated the effect of the motion correction algorithm (MCA) on image quality and interpretability by heart rate (HR) in coronary CT angiography (CCTA). MATERIALS AND METHODS: For 105 patients (6 HR groups) undergoing CCTA, 2 readers independently graded the image quality of the 4 major coronary arteries reconstructed with and without MCA at diastole with HR ≤64 bpm and at systole and diastole ≥65 bpm using a 5-point scale. For each HR group and cardiac phase, we compared per-vessel and per-segment image quality using Wilcoxon signed rank test and percentages of interpretable image quality (scores 3-5) among without MCA at diastole with HR ≤64 bpm, as a reference, with MCA at diastole ≤69 bpm and at systole 70-79 bpm using the chi-square test. RESULTS: The motion correction algorithm reconstruction provided similar or better image quality and interpretability in all groups, with 96-100 % per-vessel (P = 0.008 for the right coronary artery; otherwise, P > 0.05) and 99 % per-segment interpretable image quality (P = 0.0002) at diastole with HR ≤69 bpm and at systole 70-79 bpm compared to the reference (88-100 and 97 %, respectively). CONCLUSION: MCA reconstruction preserved image quality and interpretability of CCTA with HR ≤79 bpm.

A method for selecting a protocol for routine body CT scan using Gemstone Spectral Imaging with or without adaptive statistical iterative reconstruction: phantom experiments.

PURPOSE: To investigate a method for selecting a protocol for body CT scan to acquire monochromatic images (MIs) by gemstone spectral imaging (GSI) with or without adaptive statistical iterative reconstruction (ASiR). MATERIALS AND METHODS: We subjected a phantom to conventional scanning at 120 kVp and 50-700 mAs and GSI at 165-600 mAs; reconstructed MIs at 65 keV with ASiR 0-100 % for GSI; placed 5 regions of interest on each of 3 consecutive reconstructed slices to obtain the averaged standard deviation (SD) as image noise for conventional scan and GSI. Linear regression analysis yielded the mAs by conventional scan that could be used to achieve similar image noise by GSI. RESULTS: To achieve similar noise, we found excellent linear correlation of mAs between GSI with ASiR 0-100 % and conventional scan (r = 1.00, P < 0.0001), and obtained a table of equivalent mAs between MIs at 65 keV and conventional CT at 120 kVp. CONCLUSIONS: We can select a protocol for body CT scan for MIs at 65 keV with or without ASiR with results comparable to those of conventional CT at 120 kVp.

[Feasibility of early ambulation three hours after transfemoral angiography using a 4 French sheath].

PURPOSE: Our objective was to evaluate the feasibility of early resumption of ambulation 3 hours after transfemoral angiography using a 4 French sheath. SUBJECTS AND METHODS: This prospective study was carried out in a selected group of men and women without impaired blood clotting (prothrombin time > 15 sec) or thrombocytopenia (platelet < 55,000/mm3). The subjects consisted of 66 men and 34 women with a mean age of 62.3 years (range 27-90 years). Incidences of rebleeding or hematoma at the site of femoral catheter insertion were investigated before and after ambulation. Rebleeding was defined as bleeding that required recompression. Hematoma was defined as a palpable, firm collection of subcutaneous blood. RESULTS: Of 100 patients who resumed full ambulation after three hours of bed rest, none (0%) had acute groin hematoma and only three (3%) showed rebleeding that had to be manually compressed. The remaining 97 patients (97%) had no problem after ambulation. CONCLUSION: Supervised resumption of ambulation 3 hours after angiography with a 4 French sheath is safe and feasible in most ambulatory patients undergoing transfemoral angiography.