[A Case of Long-Term Survival after Chemotherapy and Ablation Therapy Using Various Approaches for Multiple Colon Cancer Liver Metastases].

A 58-year-old man with unresectable sigmoid colon cancer and multiple liver metastases(H2, more than 30)received chemotherapy for 2 years. Subsequently, the patient was diagnosed with stenosis of the primary lesion and 5 bilobar, metastatic tumors. Simultaneous resection was unsuitable because of the performance status and comorbidities of the patient. The first surgery consisted of laparoscopic-assisted sigmoidectomy, laparoscopic microwave coagulation therapy(MCT), and percutaneous radiofrequency ablation(RFA). Percutaneous RFA was additionally performed after 2 months. Since 2 liver metastases(S3 and S8)were inadequately treated, 3 courses of P-mab plus FOLFIRI were administered. Finally, laparoscopic- assisted RFA was performed. Subsequently, serum CEA reduced from 288.3 ng/mL to the normal level. We used fusion imaging US, sonazoid US, laparoscopic convex probe, and ICG fluorescence imaging for ablation therapy. Chemotherapy and ablation therapy using various approaches can control unresectable multiple liver metastases and prolong survival by more than 3 years.

[A Patient with Multiple Colorectal Liver Metastases for Whom Partial Splenic Embolization Contributed Extremely to Maintain Multidisciplinary Treatment].

After approximately 2.5 years of chemotherapy at the referred hospital, a 69-year-old man with double colon cancer and unresectable liver metastases(H3)sought consultation. A total of 8 liver metastases were deemed resectable; however, the disease was progressive. He received 2 courses of mFOLFOX6 plus Bmab before hepatectomy. Seven weeks after starting chemotherapy, Grade 4 thrombocytopenia occurred, which required platelet transfusion. Ten weeks after, curative parenchymal- preserving hepatectomy was performed under platelet transfusion. Hematologic examination including bone marrow aspiration showed no significant abnormalities, including normal megakaryocyte formation. Therefore, the patient was diagnosed with thrombocytopenia due to sinusoidal obstruction syndrome associated with past chemotherapy including oxaliplatin. Partial splenic embolization(PSE)was performed 8 weeks after the first hepatectomy. The infarcted splenic ratio was 79.5%, and the infarcted splenic volume was 444.3 mL. Curative resection of the primary colorectal cancer and the 2nd hepatectomy for the newly developed recurrent liver lesions was successfully performed at 2 weeks and 19 weeks after PSE, respectively. Platelet transfusion was never required in the perioperative period of the 2 operations performed after the PSE. Forty-five months after the initial treatment, the patient is alive with no recurrent tumors and normal tumor marker levels.

Dual-layer DECT for multiphasic hepatic CT with 50 percent iodine load: a matched-pair comparison with a 120 kVp protocol.

OBJECTIVES: To evaluate the image quality and lesion conspicuity of virtual-monochromatic-imaging (VMI) with dual-layer DECT (DL-DECT) for reduced-iodine-load multiphasic-hepatic CT. METHODS: Forty-five adults with renal dysfunction who had undergone hepatic DL-DECT with 300-mgI/kg were included. VMI (40-70-keV, DL-DECT-VMI) was generated at each enhancement phase. As controls, 45 matched patients undergoing standard 120-kVp protocol (120-kVp, 600-mgI/kg, and iterative reconstruction) were included. We compared the size-specific dose estimate (SSDE), image noise, CT attenuation, and contrast-to-noise ratio (CNR) between protocols. Two radiologists scored the image quality and lesion conspicuity. RESULTS: SSDE was significantly lower in DL-DECT group (p < 0.01). Image noise of DL-DECT-VMI was almost constant at each keV (differences of ≤15%) and equivalent to or lower than of 120-kVp. As the energy decreased, CT attenuation and CNR gradually increased; the values of 55-60 keV images were almost equivalent to those of standard 120-kVp. The highest scores for overall quality and lesion conspicuity were assigned at 40-keV followed by 45 to 55-keV, all of which were similar to or better than of 120-kVp. CONCLUSIONS: For multiphasic-hepatic CT with 50% iodine-load, DL-DECT-VMI at 40- to 55-keV provides equivalent or better image quality and lesion conspicuity without increasing radiation dose compared with standard 120-kVp protocol. KEY POINTS: • 40-55-keV yields optimal image quality for half-iodine-load multiphasic-hepatic CT with DL-DECT. • DL-DECT protocol decreases radiation exposure compared with 120-kVp scans with iterative reconstruction. • 40-keV images maximise conspicuity of hepatocellular carcinoma especially at hepatic-arterial phase.

Correlation of left ventricular dyssynchrony on gated myocardial perfusion SPECT analysis with extent of late gadolinium enhancement on cardiac magnetic resonance imaging in hypertrophic cardiomyopathy.

Myocardial perfusion-single-photon emission computed tomography (MP-SPECT) is used to evaluate microvascular dysfunction and coexisting coronary artery disease in patients with hypertrophic cardiomyopathy (HCM). Phase analysis in gated MP-SPECT can provide additional information on left ventricular (LV) dyssynchrony, while the extent of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging is an important prognostic factor in patients with HCM. We, therefore, sought to investigate the relationship of dyssynchrony by phase analysis on gated MP-SPECT and LGE on CMR imaging in 22 patients with HCM who underwent both stress/rest-gated MP-SPECT and contrast-enhanced CMR imaging. LV dyssynchrony parameters [phase standard deviation (SD) and histogram bandwidth] from gated MP-SPECT were compared with LGE parameters from CMR imaging [L/C contrast and %LGE calculated, respectively, as LGE intensity/LV cavity intensity and (LGE volume/myocardial volume) × 100]. Phase SD and histogram bandwidth showed strong correlation with %LGE (r = 0.73, p < 0.0001 and r = 0.73, p < 0.0001, respectively), although they did not significantly correlate with L/C contrast (r = 0.30, p = 0.17 and r = 0.26, p < 0.25, respectively). The LV dyssynchrony derived from gated MP-SPECT strongly correlated with the extent of LGE on CMR imaging. In conclusion, our investigation suggests that gated MP-SPECT may be useful not only for the assessment of myocardial ischemia but also the extent of myocardial replacement fibrosis.

Using 80 kVp on a 320-row scanner for hepatic multiphasic CT reduces the contrast dose by 50 % in patients at risk for contrast-induced nephropathy.

OBJECTIVES: We evaluated the effects of a low contrast material (CM) dose protocol using 80-kVp on the image quality of hepatic multiphasic CT scans acquired on a 320-row CT scanner. METHODS: We scanned 30 patients with renal insufficiency (eGFR < 45 mL/min/1.73 m2) using 80-kVp and a CM dose of 300mgI/kg. Another 30 patients without renal insufficiency (eGFR > 60 mL/min/1.73 m2) were scanned with the conventional 120-kVp protocol and the standard CM dose of 600mgI/kg. Quantitative image quality parameters, i.e. CT attenuation, image noise, and the contrast-to-noise ratio (CNR) were compared and the visual image quality was scored on a four-point scale. The volume CT dose index (CTDIvol) and the size-specific dose estimate (SSDE) recorded with the 80- and the 120-kVp protocols were also compared. RESULTS: Image noise and contrast enhancement were equivalent for the two protocols. There was no significant difference in the CNR of all anatomic sites and in the visual scores for overall image quality. The CTDIvol and SSDE were approximately 25-30 % lower under the 80-kVp protocol. CONCLUSION: Hepatic multiphase CT using 80-kVp on a 320-row CT scanner allowed for a decrease in the CM dose and a reduction in the radiation dose without image quality degradation in patients with renal insufficiency. KEY POINTS: • The 80-kVp CT protocol enabled reduction of contrast dose by 50 % • The 80-kVp CT protocol reduced the radiation dose by 25-33 % • There was no degradation in the image quality of the 80-kVp protocol.

Radiation dose reduction using 100-kVp and a sinogram-affirmed iterative reconstruction algorithm in adolescent head CT: Impact on grey-white matter contrast and image noise.

OBJECTIVES: To retrospectively evaluate the image quality and radiation dose of 100-kVp scans with sinogram-affirmed iterative reconstruction (IR) for unenhanced head CT in adolescents. METHODS: Sixty-nine patients aged 12-17 years underwent head CT under 120- (n = 34) or 100-kVp (n = 35) protocols. The 120-kVp images were reconstructed with filtered back-projection (FBP), 100-kVp images with FBP (100-kVp-F) and sinogram-affirmed IR (100-kVp-S). We compared the effective dose (ED), grey-white matter (GM-WM) contrast, image noise, and contrast-to-noise ratio (CNR) between protocols in supratentorial (ST) and posterior fossa (PS). We also assessed GM-WM contrast, image noise, sharpness, artifacts, and overall image quality on a four-point scale. RESULTS: ED was 46% lower with 100- than 120-kVp (p < 0.001). GM-WM contrast was higher, and image noise was lower, on 100-kVp-S than 120-kVp at ST (p < 0.001). CNR of 100-kVp-S was higher than of 120-kVp (p < 0.001). GM-WM contrast of 100-kVp-S was subjectively rated as better than of 120-kVp (p < 0.001). There were no significant differences in the other criteria between 100-kVp-S and 120-kVp (p = 0.072-0.966). CONCLUSIONS: The 100-kVp with sinogram-affirmed IR facilitated dramatic radiation reduction and better GM-WM contrast without increasing image noise in adolescent head CT. KEY POINTS: • 100-kVp head CT provides 46% radiation dose reduction compared with 120-kVp. • 100-kVp scanning improves subjective and objective GM-WM contrast. • Sinogram-affirmed IR decreases head CT image noise, especially in supratentorial region. • 100-kVp protocol with sinogram-affirmed IR is suited for adolescent head CT.

Breast dose reduction for chest CT by modifying the scanning parameters based on the pre-scan size-specific dose estimate (SSDE).

OBJECTIVE: To investigate the usefulness of modifying scanning parameters based on the size-specific dose estimate (SSDE) for a breast-dose reduction for chest CT. MATERIALS AND METHODS: We scanned 26 women with a fixed volume CT dose index (CTDIvol) (15 mGy) and another 26 with a fixed SSDE (15 mGy) protocol (protocol 1 and 2, respectively). In protocol 2, tube current was calculated based on the patient habitus obtained on scout images. We compared the mean breast dose and the inter-patient breast dose variability and performed linear regression analysis of the breast dose and the body mass index (BMI) of the two protocols. RESULTS: The mean breast dose was about 35 % lower under protocol 2 than protocol 1 (10.9 mGy vs. 16.8 mGy, p < 0.01). The inter-patient breast dose variability was significantly lower under protocol 2 than 1 (1.2 mGy vs. 2.5 mGy, p < 0.01). We observed a moderate negative correlation between the breast dose and the BMI under protocol 1 (r = 0.43, p < 0.01); there was no significant correlation (r = 0.06, p = 0.35) under protocol 2. CONCLUSION: The SSDE-based protocol achieved a reduction in breast dose and in inter-patient breast dose variability. KEY POINTS: • CT scan parameters can be modified based on the pre-scan SSDE. • The pre-scan SSDE is useful for a breast dose reduction. • The fixed SSDE protocol reduced individual variations in the breast dose.

Cardiovascular magnetic resonance myocardial T1 mapping to detect and quantify cardiac involvement in familial amyloid polyneuropathy.

OBJECTIVES: This study sought to explore the potential role of non-contrast T1 mapping for the detection and quantification of cardiac involvement in familial amyloid polyneuropathy (FAP). METHODS: Japanese patients with FAP [n = 41, age 53.2 ± 13.9 years, genotype Val30Met (n = 25), non-Val30Met (n = 16)] underwent cardiac magnetic resonance imaging that included T1 mapping (saturation-recovery method) and late gadolinium-enhanced (LGE) imaging on a 3.0-T MR scanner. Their native T1 was measured on mid-ventricular short-axis images and compared with 30 controls. RESULTS: Of the 41 FAP patients 29 were LGE positive. The native T1 was significantly higher in FAP patients than in the controls (1,634.1 ± 126.3 ms vs. 1,432.4 ± 69.0 ms, p < 0.01), significantly higher in LGE-positive- than LGE-negative FAP patients (1,687.1 ± 104.4 ms vs. 1,505.4 ± 68.5 ms, p < 0.01), and significantly higher in LGE-negative FAP patients than the controls (p < 0.01). A native T1 cutoff value of 1,610 ms yielded 85.4% accuracy for identifying LGE-positive FAP. The native T1 significantly correlated with the interventricular septum wall thickness, the left ventricular mass, the LGE volume, the plasma B-type natriuretic peptide level, and the E/e' ratio (all p < 0.01). CONCLUSION: T1 mapping is of high diagnostic accuracy for the detection of LGE-positive FAP. The native myocardial T1 may be correlated with the severity of cardiac amyloid deposition. KEY POINTS: • The native T1 was higher in FAP patients than the controls. • The native T1 was higher in LGE-positive- than LGE-negative FAP patients. • The native T1 was higher in LGE-negative FAP patients than the controls. • The native T1 correlated with clinical markers of systolic and diastolic dysfunction. • Myocardial T1 mapping is of high diagnostic accuracy for detecting LGE-positive FAP.

Identification and Assessment of Cardiac Amyloidosis by Myocardial Strain Analysis of Cardiac Magnetic Resonance Imaging.

BACKGROUND: We explored the usefulness of myocardial strain analysis on cardiac magnetic resonance imaging (CMR) scans for the identification of cardiac amyloidosis.Methods and Results:The 61 patients with systemic amyloidosis underwent 3.0-T CMR, including CMR tagging and late-gadolinium enhanced (LGE) imaging. The circumferential strain (CS) of LGE-positive and LGE-negative patients was measured on midventricular short-axis images and compared. Logistic regression modeling of CMR parameters was performed to detect patients with LGE-positive cardiac amyloidosis. Of the 61 patients with systemic amyloidosis 48 were LGE-positive and 13 were LGE-negative. The peak CS was significantly lower in the LGE-positive than in the LGE-negative patients (-9.5±2.3 vs. -13.3±1.4%, P<0.01). The variability in the peak CS time was significantly greater in the LGE-positive than in the LGE-negative patients (46.1±24.5 vs. 21.2±20.1 ms, P<0.01). The peak CS significantly correlated with clinical biomarkers. The sensitivity, specificity, and accuracy of the diagnostic model using CS parameters for the identification of LGE-positive amyloidosis were 93.8%, 76.9%, and 90.2%, respectively. CONCLUSIONS: Myocardial strain analysis by CMR helped detect LGE-positive amyloidosis without the need for contrast medium. The peak CS and variability in the peak CS time may correlate with the severity of cardiac amyloid deposition and may be more sensitive than LGE imaging for the detection of early cardiac disease in patients with amyloidosis.

Cerebral bone subtraction CT angiography using 80 kVp and sinogram-affirmed iterative reconstruction: contrast medium and radiation dose reduction with improvement of image quality.

INTRODUCTION: The purpose of this study was to evaluate the feasibility of a contrast medium (CM), radiation dose reduction protocol for cerebral bone-subtraction CT angiography (BSCTA) using 80-kVp and sinogram-affirmed iterative reconstruction (SAFIRE). METHODS: Seventy-five patients who had undergone BSCTA under the 120- (n = 37) or the 80-kVp protocol (n = 38) were included. CM was 370 mgI/kg for the 120-kVp and 296 mgI/kg for the 80-kVp protocol; the 120- and the 80-kVp images were reconstructed with filtered back-projection (FBP) and SAFIRE, respectively. We compared effective dose (ED), CT attenuation, image noise, and contrast-to-noise ratio (CNR) of two protocols. We also scored arterial contrast, sharpness, depiction of small arteries, visibility near skull base/clip, and overall image quality on a four-point scale. RESULTS: ED was 62% lower at 80- than 120-kVp (0.59 ± 0.06 vs 1.56 ± 0.13 mSv, p < 0.01). CT attenuation of the internal carotid artery (ICA) and middle cerebral artery (MCA) was significantly higher on 80- than 120-kVp (ICA: 557.4 ± 105.7 vs 370.0 ± 59.3 Hounsfield units (HU), p < 0.01; MCA: 551.9 ± 107.9 vs 364.6 ± 62.2 HU, p < 0.01). The CNR was also significantly higher on 80- than 120-kVp (ICA: 46.2 ± 10.2 vs 36.9 ± 7.6, p < 0.01; MCA: 45.7 ± 10.0 vs 35.7 ± 9.0, p < 0.01). Visibility near skull base and clip was not significantly different (p = 0.45). The other subjective scores were higher with the 80- than the 120-kVp protocol (p < 0.05). CONCLUSION: The 80-kVp acquisition with SAFIRE yields better image quality for BSCTA and substantial reduction in the radiation and CM dose compared to the 120-kVp with FBP protocol.

Paradoxical Effect of Cardiac Output on Arterial Enhancement at Computed Tomography: Does Cardiac Output Reduction Simply Result in an Increase in Aortic Peak Enhancement?

OBJECTIVE: The aim of this study was to evaluate the effect of cardiac output (CO) on aortic peak enhancement using protocols with different contrast material (CM) injection durations. METHODS: We used a flow phantom that simulated the human circulatory system. Contrast material was injected at a rate of 4.0 mL/s for a period of 2.5, 5, 10, 15, or 20 seconds for a CO of 2.8, 4.2, and 5.6 L/min. Single-level serial computed tomography scans of the simulated aorta were acquired after the start of CM delivery, and aortic peak enhancement was recorded under the different injection protocols. RESULTS: Under a long injection duration protocol (20 seconds), a decrease in CO increased aortic peak enhancement proportionally (CO of 2.8 L/min, 420 Hounsfield units [HU]; CO of 4.2 L/min, 365 HU; CO of 5.6 L/min, 291 HU). However, this effect was decreased under shorter injection duration protocols (5, 10, and 15 seconds); under the shortest (2.5-second) injection duration protocol, a decrease in CO resulted in a decrease in aortic peak enhancement (CO of 2.8 L/min, 36 HU; CO of 4.2 L/min, 51 HU; CO of 5.6 L/min, 55 HU). CONCLUSIONS: The magnitude of the effect of CO on aortic peak enhancement depends on the CM injection duration.

Iterative Reconstruction Designed for Brain CT: A Correlative Study With Filtered Back Projection for the Diagnosis of Acute Ischemic Stroke.

OBJECTIVES: The objective of this study is to evaluate the usefulness of iterative model reconstruction designed for brain computed tomography (CT) (IMR-Neuro) for the diagnosis of acute ischemic stroke. METHODS: This retrospective study included 20 patients with acute middle cerebral artery infarction who have undergone brain CT and 20 nonstroke patients (control). We reconstructed axial images with filtered back projection (FBP) and IMR-Neuro (slice thickness, 1 and 5 mm). We compared the CT number of the infarcted area, the image noise, contrast, and the contrast to noise ratio of the infarcted and the noninfarcted areas between the different reconstruction methods. We compared the performance of 10 radiologists in the detection of parenchymal hypoattenuation between 2 techniques using the receiver operating characteristic (ROC) techniques with the jackknife method. RESULTS: The image noise was significantly lower with IMR-Neuro [5 mm: 2.5 Hounsfield units (HU) ± 0.5, 1 mm: 3.9 HU ± 0.5] than with FBP (5 mm: 4.9 HU ± 0.5, 1 mm: 10.1 HU ± 1.4) (P < 0.01). The contrast to noise ratio was significantly greater with IMR-Neuro (5 mm: 2.6 ± 2.1, 1 mm: 1.6 ± 1.3) than with FBP (5 mm: 1.2 ± 1.0; 1 mm: 0.6 ± 0.5) (P < 0.01). The value of the average area under the receiver operating curve was significantly higher with IMR-Neuro than FBP (5 mm: 0.79 vs 0.74, P = 0.04; 1 mm: 0.76 vs 0.69, P = 0.04). CONCLUSIONS: Compared with FBP, IMR-Neuro improves the image quality and the performance for the detection of parenchymal hypoattenuation with acute ischemic stroke.

Radiation-induced Liver Injury after 3D-conformal Radiotherapy for Hepatocellular Carcinoma: Quantitative Assessment Using Gd-EOB-DTPA-enhanced MRI.

Focal liver reaction (FLR) appears in the hepatobiliary-phase images of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI) following radiotherapy (RT). We investigated the threshold dose (TD) for FLR development in 13 patients with hepatocellular carcinoma (HCC) who underwent three-dimensional conformal radiotherapy (3D-CRT) with 45 Gy in 15 fractions. FLR volumes (FLRVs) were calculated based on planning CT images by referring to fused hepatobiliary- phase images. We also calculated the TD and the irradiated volumes (IVs) of the liver parenchyma at a given dose of every 5 Gy (IVdose) based on a dose-volume histogram (DVH). The median TD was 35.2 Gy. The median IV20, IV25, IV30, IV35, IV40, and IV45 values were 371.1, 274.8, 233.4, 188.6, 145.8, and 31.0 ml, respectively. The median FLRV was 144.9 ml. There was a significant difference between the FLRV and IV20, IV25, and IV45 (p<0.05), but no significant differences between the FLRV and IV30, IV35, or IV40. These results suggest that the threshold dose of the FLR is approx. 35 Gy in HCC patients who undergo 3D-CRT in 15 fractions. The percentage of the whole liver volume receiving a dose of more than 30-40 Gy (V30-40) is a potential candidate optimal DVH parameter for this fractionation schedule.

256-Slice coronary computed tomographic angiography in patients with atrial fibrillation: optimal reconstruction phase and image quality.

OBJECTIVES: To assess the optimal reconstruction phase and the image quality of coronary computed tomographic angiography (CCTA) in patients with atrial fibrillation (AF). METHODS: We performed CCTA in 60 patients with AF and 60 controls with sinus rhythm. The images were reconstructed in multiple phases in all parts of the cardiac cycle, and the optimal reconstruction phase with the fewest motion artefacts was identified. The coronary artery segments were visually evaluated to investigate their assessability. RESULTS: In 46 (76.7 %) patients, the optimal reconstruction phase was end-diastole, whereas in 6 (10.0 %) patients it was end-systole or mid-diastole, and in 2 (3.3 %) patients it was another cardiac phase. In 53 (88.3 %) of the controls, the optimal reconstruction phase was mid-diastole, whereas it was end-systole in 4 (6.7 %), and in 3 (5.0 %) it was another cardiac phase. There was a significant difference between patients with AF and the controls in the optimal phase (p < 0.01) but not in the visual image quality score (p = 0.06). CONCLUSIONS: The optimal reconstruction phase in most patients with AF was the end-diastolic phase. The end-systolic phase tended to be optimal in AF patients with higher average heart rates. KEY POINTS: The optimal reconstruction phase in 76.7 % of patients with atrial fibrillation (AF) was end-diastole. The end-systolic phase was optimal in AF patients with higher heart rates. ECG and heart-rate control are necessary to obtain end-diastolic images with fewer motion artefacts.

Reduction of metallic coil artefacts in computed tomography body imaging: effects of a new single-energy metal artefact reduction algorithm.

OBJECTIVES: We evaluated the effect of a single-energy metal artefact reduction (SEMAR) algorithm for metallic coil artefact reduction in body imaging. METHODS: Computed tomography angiography (CTA) was performed in 30 patients with metallic coils (10 men, 20 women; mean age, 67.9 ± 11 years). Non-SEMAR images were reconstructed with iterative reconstruction alone, and SEMAR images were reconstructed with the iterative reconstruction plus SEMAR algorithms. We compared image noise around metallic coils and the maximum diameters of artefacts from coils between the non-SEMAR and SEMAR images. Two radiologists visually evaluated the metallic coil artefacts utilizing a four-point scale: 1 = extensive; 2 = strong; 3 = mild; 4 = minimal artefacts. RESULTS: The image noise and maximum diameters of the artefacts of the SEMAR images were significantly lower than those of the non-SEMAR images (65.1 ± 33.0 HU vs. 29.7 ± 10.3 HU; 163.9 ± 54.8 mm vs. 10.3 ± 19.0 mm, respectively; P < 0.001). Better visual scores were obtained with the SEMAR technique (3.4 ± 0.6 vs. 1.0 ± 0.0, P < 0.001). CONCLUSIONS: The SEMAR algorithm significantly reduced artefacts caused by metallic coils compared with the non-SEMAR algorithm. This technique can potentially increase CT performance for the evaluation of post-coil embolization complications. KEY POINTS: • The new algorithm involves a raw data- and image-based reconstruction technique. • The new algorithm mitigates artefacts from metallic coils on body CT images. • The new algorithm significantly reduced artefacts caused by metallic coils. • The metal artefact reduction algorithm improves CT image quality after coil embolization.

Clinical impact of model-based type iterative reconstruction with fast reconstruction time on image quality of low-dose screening chest CT.

BACKGROUND: Model-based type iterative reconstruction algorithms with fast reconstruction times are now available. The clinical feasibility of their reconstruction has not been evaluated adequately. PURPOSE: To investigate the effects of model-based type iterative reconstruction, i.e. iterative model reconstruction (IMR), with fast reconstruction time on the qualitative and quantitative image quality at low-dose chest computed tomography (CT). MATERIAL AND METHODS: Thirty-one patients undergoing low-dose screening chest CT were enrolled. Images were reconstructed using filtered back projection (FBP), hybrid iterative reconstruction (HIR), and IMR algorithms. The CT attenuation and image noise for all reconstructions were calculated at the lung apex, middle, and base. Using a 4-point scale, two reviewers visually evaluated the image quality with respect to vessel sharpness, streak artifact, the mediastinum, and the overall image quality of each reconstruction method. RESULTS: The mean estimated effective dose was 1.0 ± 0.3 mSv. There was no significant difference in the CT attenuation among the three reconstructions. The mean image noise of FBP, HIR, and IMR images was 124.3 ± 57.3, 34.8 ± 10.2, and 22.9 ± 5.8 HU, respectively. There were significant differences for all comparison combinations among the three methods (P < 0.01). The best subjective overall image quality for the lung and mediastinum was obtained with IMR (P < 0.01). The reconstruction time for IMR was within 3 min in all cases. CONCLUSION: At low-dose chest CT, IMR can improve the qualitative and quantitative visualization of both lung and mediastinal structures especially in the lung apex at a clinically acceptable reconstruction time. Its application may improve diagnostic performance.

Patient-specific tube-voltage selection at coronary CT angiography based on the combination of X-ray attenuation on scout views and body mass index: how can appropriate radiation dose be achieved?

BACKGROUND: Body weight, body mass index (BMI), and scout X-ray radiographic attenuation can be used to predict image noise on computed tomographic coronary angiography (CTCA) images. PURPOSE: To use a formula to predict patient-specific image noise and then select an appropriate CTCA patient-specific tube voltage for better radiation control. MATERIAL AND METHODS: Forty-eight patients who underwent CTCA imaging at 120 kVp were reviewed, and their patient information and scouting X-ray radiographic attenuations were recorded to identify the best correlations between patient data and image noise and to develop a predicted image noise formula. Subsequently, 54 patients subjected to scanning at 100 or 120 kVp, depending on the noise predicted by our formula, were prospectively studied. Two radiologists visually assessed the image quality of the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) by consensus readings. RESULTS: The predicted image noise = 0.939 BMI + 0.025 scouting attenuation + 20.16. The median value of the overall image noise was 30.55 HU at 120 kVp and 29.85 HU at 100 kVp. The mean visual evaluation scores at 100 and 120 kVp were 3.25 and 3.24 for the proximal RCA, 3.40 and 3.26 for the proximal LAD, and 3.30 and 3.15 for the proximal LCX, respectively. CONCLUSION: The BMI and scouting X-ray radiographic attenuation can be combined to predict the CTCA image noise. Our prediction formula is useful for deciding when to switch from the 120- to the 100-kVp technique.

Improved image quality at 256-slice coronary CT angiography in patients with a high heart rate and coronary artery disease: comparison with 64-slice CT imaging.

BACKGROUND: The 256-slice computed tomography (CT) scanners with wider detector coverage and faster gantry rotation speed are now available. The performance of scanners that feature a rotation speed of 270 ms at coronary CT angiography (CCTA) has not been evaluated in patients with a higher heart rate. PURPOSE: To evaluate the image quality of 256-slice CT with faster gantry rotation speed in patients undergoing CCTA. MATERIAL AND METHODS: We enrolled 886 patients; 357(40.3%) underwent study on a 64-slice CT at a rotation speed of 420 ms, the other 529 (59.7%) were examined using a 256-slice CT scanner at 270 ms. Two observers judged the image quality of 2658 imaged coronary arteries on a 4-point scale. RESULTS: The mean image quality score was significantly higher for the 256 - than the 64-slice CT scans (3.94 ± 0.28 vs. 3.73 ± 0.61; P < 0.01). There was no significant difference in the image quality scores between 64 - and 256-slice scans in patients whose heart rate (HR) was <60 bpm. However, in patients whose HR exceeded 60 bpm these scores were significantly higher for 256-slice CT images (P < 0.01). CONCLUSION: CCTA performed on the 256-slice CT scanner yielded significantly better image quality in patients with an HR exceeding 60 bpm.

Highly Advanced Colorectal Liver Metastases Successfully Treated With Fluorouracil Plus Leucovorin Monotherapy and Microwave Ablation.

BACKGROUND: Fluorouracil plus leucovorin (5-FU/LV) is a less toxic but mild chemotherapy. CASE REPORT: A 63-year-old male patient with rectal cancer and multiple colorectal liver metastases (CRLM, total volume of 1,826 ml) was hospitalized. He had several poor prognostic factors, including elevated levels of tumor markers, with carcinoembryonic antigen and carbohydrate antigen 19-9 levels of 17,119 ng/ml and 7,617 U/ml, respectively. Additionally, the patient had a low body mass index, poor performance status, and a history of apparent weight loss. After capecitabine and oxaliplatin for four cycles, 5-FU/LV has been lasting for nine months. Interestingly, tumor marker levels returned close to normal limits, and the total CRLM volume decreased to 154 ml without any enhancements. The patient's general condition clearly improved after a year of chemotherapy. CONCLUSION: Chemotherapy with 5-FU/LV and percutaneous microwave ablation is beneficial to achieve tumor control in patients with highly advanced liver-only CRLM and poor general condition.