Daniel Spira

Sinogram affirmed iterative reconstruction in head CT: Improvement of objective and subjective image quality with concomitant radiation dose reduction

PURPOSE Iterative reconstruction has recently been revisited as a promising concept for substantial CT dose reduction. The purpose of this study was to assess the potential benefit of sinogram affirmed iterative reconstruction (SAFIRE) in head CT by comparing objective and subjective image quality at reduced tube current with standard dose filtered back projection (FBP). MATERIALS AND METHODS Non-contrast reduced dose head CT (255 mAs, CTDIvol 47.8 mGy) was performed in thirty consecutive patients and reconstructed with SAFIRE and FBP. Images were assessed in terms of quantitative and qualitative image quality and compared with FBP of standard dose acquisitions (320 mAs, CTDI vol 59.7 mGy). RESULTS In reduced dose CT examinations, use of SAFIRE versus FBP resulted in 47% increase in contrast-to-noise ratio (CNR) (2.49 vs. 1.69; p<0.0001). While reduction of tube current was associated with 13% decrease in CNR, quantitative degradation of image quality at lower dose was more than compensated through SAFIRE (2.49 vs. 1.96; p=0.0004). Objective measurements of image sharpness were comparable between FBP and SAFIRE reconstructions (575.9 ± 74.1 vs. 583.4 ± 74.7 change in HU/Pixel; p=0.28). Compared to standard dose FBP, subjective grading of noise as well as overall image quality scores were significantly improved when SAFIRE was used in reduced dose exams (1.3 vs. 1.6, p=0.006; 1.3 vs. 1.7, p=0.026). CONCLUSION At 20% dose reduction, reconstruction of head CT by SAFIRE provides above standard objective and subjective image quality, suggesting potential for more vigorous dose savings in neuroradiology CT applications.

Assessment of tumor vascularity in lung cancer using volume perfusion CT (VPCT) with histopathologic comparison: a further step toward an individualized tumor characterization.

Objective To measure perfusion in different lung cancer subtypes and compare results with histopathological/immunohistochemical results. Methods Seventy-two consecutive untreated patients with lung cancer (40 adenocarcinomas, 20 squamous cell, and 12 small cell lung cancers) were enrolled. A 40-second volume perfusion computed tomography of the tumor bulk was obtained. Blood flow (BF), blood volume (BV), and transit constant were determined. Tumor volume and tumor necrosis were determined on contrast-enhanced computed tomography. Pathologic specimens were assessed for microvessel density (MVD), hypoxia-induced transcription (hif-1/-2), and proliferation (Ki-67). Results Higher MVD is associated with higher BF and BV. Higher tumor grade leads to lower BF but increased necrosis and tumor volume. Markers of hypoxia were independent from perfusion parameters, extent of necrosis or MVD. Blood flow, BV, and MVD were not significantly different among lung cancer subtypes. Transit constant was significantly reduced in small cell lung cancer versus adenocarcinoma. Conclusions Perfusion values are related to MVD and tumor grade but vary considerably among lung cancer subtypes.

Tin-filter Enhanced Dual-Energy-CT: Image Quality and Accuracy of CT Numbers in Virtual Noncontrast Imaging

OBJECTIVES To measure and compare the objective image quality of true noncontrast (TNC) images with virtual noncontrast (VNC) images acquired by tin-filter-enhanced, dual-source, dual-energy computed tomography (DECT) of upper abdomen. MATERIALS AND METHODS Sixty-three patients received unenhanced abdominal CT and enhanced abdominal DECT (100/140 kV with tin filter) in portal-venous phase. VNC images were calculated from the DECT datasets using commercially available software. The mean attenuation of relevant tissues and image quality were compared between the TNC and VNC images. Image quality was rated objectively by measuring image noise and the sharpness of object edges using custom-designed software. Measurements were compared using Student two-tailed t-test. Correlation coefficients for tissue attenuation measurements between TNC and VNC were calculated and the relative deviations were illustrated using Bland-Altman plots. RESULTS Mean attenuation differences between TNC and VNC (HUTNC - HUVNC) image sets were as follows: right liver lobe -4.94 Hounsfield units (HU), left liver lobe -3.29 HU, vena cava -2.19 HU, spleen -7.46 HU, pancreas 1.29 HU, fat -11.14 HU, aorta 1.29 HU, bone marrow 36.83 HU (all P < .05); right kidney 0.46 HU, left kidney 0.56 HU, vena portae -0.48 HU and muscle -0.62 HU (nonsignificant). Good correlations between VNC and TNC series were observed for liver, vena portae, kidneys, pancreas, muscle and bone marrow (Pearsons correlation coefficient ≥0.75). Mean image noise was significantly higher in TNC images (P < .0001). Measurements of edge sharpness revealed no significant differences between VNC and TNC images (P = .19). CONCLUSION The Hounsfield units in VNC images closely resemble TNC images in the majority of the organs of the upper abdomen (kidneys, liver, pancreas). In spleen and fat, Hounsfield numbers in VNC images are tend to be higher than in TNC images. VNC images show a low image noise and satisfactory edge sharpness. Other criteria of image quality and the depiction of certain lesions need to be evaluated additionally.

MRI Findings in Psoriatic Arthritis of the Hands

OBJECTIVE The purpose of this essay is to provide a practical review of the spectrum of morphologic and functional MRI findings in psoriatic arthritis of the hand joints. CONCLUSION The MRI findings of psoriatic arthritis include enthesitis, bone marrow edema, and periostitis accompanying articular or flexor tendon sheath synovitis in the early stage accompanied by destructive and proliferative bony changes, subluxation, and ankylosis in the late stage.

Volume perfusion-CT of the liver: Insights and applications

The purpose of this article is to provide an up-to-date view on the spectrum of applications of volume perfusion-CT in the liver. Volume perfusion-CT yields important information on liver architecture and function by enabling quantification of dual liver parenchymal blood supply. Additional characterization of diffuse and focal liver diseases by illustration of distinct flow dynamics and permeability may become an important adjunct in the CT-evaluation of liver pathologies.

Systemic IgG4-Related Sclerosing Disease: Spectrum of Imaging Findings and Differential Diagnosis

OBJECTIVE The purposes of this article are to provide a practical review of the spectrum of imaging findings in patients with systemic IgG4-related sclerosing disease and to address the differential diagnoses. CONCLUSION IgG4-related sclerosing disease is a systemic disorder that can involve almost any organ. The imaging findings consist of diffuse and focal organ infiltration and encasement by inflammatory and fibrotic tissue. Awareness of the spectrum of imaging findings in IgG4-related disease should prompt further evaluation for systemic manifestations to avoid misdiagnosis.

Intraobserver and interobserver agreement of volume perfusion CT (VPCT) measurements in patients with lung lesions

OBJECTIVES To evaluate intraobserver and interobserver agreement of manually encompassed lung lesions for perfusion measurements using volume-perfusion computed tomography (VPCT). MATERIALS AND METHODS Institutional review board approval and informed consent were obtained. HIPAA guidelines were followed. A 65-s dynamic study was acquired with scan parameters 80 kV, 60 mAs (80 mAs for patients ≥ 70 kg), 128 × 0.6mm collimation. Blood flow (BF), blood volume (BV) and K(trans) parameters were determined by syngo volume perfusion CT body with 88 lesions analyzed retrospectively. RESULTS Within-subject coefficients of variation for intraobserver agreement (range 6.59-12.82%) were superior to those for interobserver agreement (range 21.75-38.30%). Size-dependent analysis revealed lower agreements for lesions <4 cm as compared to larger lesions. Additionally, agreements of the upper, middle and lower lung zones were different. CONCLUSIONS Intraobserver agreement was substantial for VPCT lung cancer perfusion measurements encouraging the use for tumor characterization and therapy response monitoring. Interobserver agreement is limited and unexperienced readers should be trained before using this new method.

Correlation between [18F]FDG PET/CT and volume perfusion CT in primary tumours and mediastinal lymph nodes of non-small-cell lung cancer

PurposeThe aim of this study was to investigate correlations between glucose metabolism as determined by [18F]FDG PET/CT and tumour perfusion as quantified by volume perfusion CT in primary tumours and mediastinal lymph nodes (MLN) of patients with non-small-cell lung cancer (NSCLC).MethodsEnrolled in the study were 17 patients with NSCLC. [18F]FDG uptake was quantified in terms of SUVmax and SUVavg. Blood flow (BF), blood volume (BV) and flow extraction product (Ktrans) were determined as perfusion parameters. The correlations between the perfusion parameters and [18F]FDG uptake values were subsequently evaluated.ResultsFor the primary tumours, no correlations were found between perfusion parameters and [18F]FDG uptake. In MLN, there were negative correlations between BF and SUVavg (r = −0.383), BV and SUVavg (r = −0.406), and BV and SUVmax (r = −0.377), but not between BF and SUVmax, Ktrans and SUVavg, or Ktrans and SUVmax. Additionally, in MLN with SUVmax >2.5 there were negative correlations between BF and SUVavg (r = −0.510), BV and SUVavg (r = −0.390), BF and SUVmax (r = −0.536), as well as BV and SUVmax (r = −0.346).ConclusionPerfusion and glucose metabolism seemed to be uncoupled in large primary tumours, but an inverse correlation was observed in MLN. This information may help improve therapy planning and response evaluation.

Can Whole-body Low-dose Multidetector CT Exclude the Presence of Myeloma Bone Disease in Patients with Monoclonal Gammopathy of Undetermined Significance (MGUS)?

RATIONALE AND OBJECTIVES To determine the benefit of using whole-body low-dose computed tomography (WBLD-CT) in patients with monoclonal gammopathy of undetermined significance (MGUS) for exclusion of multiple myeloma (MM) bone disease. MATERIALS AND METHODS Seventy-one consecutive patients with confirmed MGUS (as defined by the latest criteria of the International Myeloma Working Group) who underwent WBLD-CT for diagnosis were identified retrospectively by a search of our institutions electronic medical record database (2002-2009). Patients were classified as low-risk or intermediate/high-risk and followed over a ≥2-year period with additional CT imaging and/or laboratory parameters. Presence of osteolysis, medullary, or extramedullary abnormalities compatible with involvement by MM was recorded. A diffuse or focal increase in medullary density to Hounsfield unit (HU) values >20 HU/>0 HU was considered suspicious for bone marrow infiltration if no other causes identifiable. RESULTS The presence of osteolysis was excluded in all 71 patients with MGUS at initial diagnosis and patients were surveilled for ≥2 years. Lytic changes were observed at follow-up in 1/71 patients that progressed to MM and were detectable via WBLD-CT at an early stage (even before a significant rise in M-protein was recorded). In 3/71 patients with MGUS (4%) suspicious bone marrow attenuation values were measured, disclosing disease progression to smoldering myeloma in another patient and false-positive results in 2/71 patients. Bone marrow attenuation assessment resulted in a specificity and negative predictive value of 97%, respectively. No significant difference with respect to bone marrow attenuation was observed in patients with low-risk MGUS versus intermediate- to high-risk MGUS. One of 71 patients showed serologic disease progression to active MM without bone abnormalities detectable. CONCLUSION WBLD-CT reliably excludes findings compatible with myeloma in MGUS and thereby complements hematologic laboratory analysis.

Increasing Bone Sclerosis During Bortezomib Therapy in Multiple Myeloma Patients: Results of a Reduced-Dose Whole-Body MDCT Study

OBJECTIVE The objective of our study was to assess the frequency, location, extent, and patterns of bone sclerosis occurring in patients with multiple myeloma (MM) during bortezomib-based therapy. MATERIALS AND METHODS From June 2003 through December 2011, 593 whole-body reduced-dose MDCT studies were performed of 79 consecutive patients receiving bortezomib. The median surveillance time was 21 months (range, 3-67 months). Baseline studies were compared with follow-up studies during therapy (follow-up 1), at the end of therapy (follow-up 2), and 12 months after cessation of bortezomib therapy (follow-up 3). We recorded any sclerotic change occurring inside or along the margins of the osteolytic lesions, in the cancellous bone, or inside preexistent medullary or extramedullary lesions. The time point of occurrence of bone sclerosis was correlated with the best hematologic response category. RESULTS Fourteen (17.7%) patients developed focal (n = 11) or diffuse (n = 3) bone sclerosis. The time window from bortezomib initiation to radiographic detection of bone sclerosis was 8 months (SD, 7 months). Sclerosis occurred at multiple sites (n = 7) or at an isolated site (n = 7). On subsequent whole-body reduced-dose MDCT studies, sclerosis further increased in seven (50%) patients. Hematologic best response during bortezomib treatment was complete response (n = 1), very good partial response (n = 2), partial response (n = 8), and stable disease (n = 3). Radiologic response at the time of sclerosis detection was partial response (n = 8), stable disease (n = 2), and progressive disease (n = 4). CONCLUSION Bone remineralization may occur during bortezomib-based therapy for MM in a substantial proportion of patients. The extent, location, and patterns of sclerosis differ among patients and are unpredictable. Sclerosis was documented even in patients showing suboptimal hematologic response.