Maximilian Schulze

MRI Findings in Inflammatory Muscle Diseases and Their Noninflammatory Mimics

OBJECTIVE The purpose of this article is to provide a practical review of the spectrum of MRI findings in inflammatory muscle diseases and their noninflammatory mimics. CONCLUSION MRI is a highly sensitive tool for the diagnosis of muscle diseases. Although it has low specificity, awareness of the potential imaging findings in the various, sometimes rare, muscular disorders is helpful for accurate diagnosis.

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.

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.

Estimation of Radiation Exposure of 128-Slice 4D-Perfusion CT for the Assessment of Tumor Vascularity

Objective We aimed to estimate the effective dose of 4D-Perfusion-CT protocols of the lung, liver, and pelvis for the assessment of tumor vascularity. Materials and Methods An Alderson-Rando phantom equipped with thermoluminescent dosimeters was used to determine the effective dose values of 4D-Perfusion-CT. Phantom measurements were performed on a 128-slice single-source scanner in adaptive 4D-spiral-mode with bidirectional table movement and a total scan range of 69 mm over a time period of nearly 120 seconds (26 scans). Perfusion measurements were simulated for the lung, liver, and pelvis under the following conditions: lung (80 kV, 60 mAs), liver (80 kV/80 mAs and 80 kV/120 mAs), pelvis (100 kV/80 mAs and 100 kV/120 mAs). Results Depending on gender, the evaluated body region and scan protocol, an effective whole-body dose between 2.9-12.2 mSv, was determined. The radiation exposure administered to gender-specific organs like the female breast tissue (lung perfusion) or to the ovaries (pelvic perfusion) led to an increase in the female specific dose by 86% and 100% in perfusion scans of the lung and the pelvis, respectively. Conclusion Due to a significant radiation dose of 4D-perfusion-CT protocols, the responsible use of this new promising technique is mandatory. Gender- and organ-specific differences should be considered for indication and planning of tumor perfusion scans.

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.

Comparison of volume perfusion computed tomography and contrast-enhanced ultrasound for assessment of therapeutic effect of transarterial chemoembolization in patients with hepatocellular carcinoma: a preliminary report

Background Evaluation of transarterial chemoembolization (TACE) by using contrast-enhanced ultrasound (CEUS) and volume perfusion computed tomography (VPCT) as methods that display tumor vascularization. Purpose To assess early results of TACE in patients with hepatocellular carcinoma (HCC) using CEUS and VPCT. Material and Methods Twenty patients with HCC underwent CEUS and VPCT in the pre- and post-TACE setting (1 day). Hepatic perfusion index (HPI), arterial liver perfusion (ALP), blood flow (BF), and blood volume (BV) were measured with VPCT. Peak intensity (PI), time-to-peak (TTP), and regional blood flow (RBF) were measured with CEUS. Sensitivity, specificity, negative and positive predictive values, and cutoff values for these parameters were calculated. Immediate tumor response after TACE was classified as responder or non-responder. Results were compared with those at follow-up after 2 and 4 months (FU2mo/FU4mo) following modified RECIST. Results CEUS and VPCT showed comparable immediate post-TACE results in 20/20 cases. Complete response was confirmed in 10/20 patients at FU2mo and in 9/20 at FU4mo. For responders, reduction in HPI, ALP, BV, and BF at day 1 post TACE proved significant (P < 0.001). For non-responders, the course of all VPCT parameters proved non-significant. A cutoff of 40% reduction in HPI and a reduction in ALP of >29.6%, in BV of >41.4%, or in BF of >53.1% was indicative of response according to FU2mo. For responders only, changes in PI (P < 0.001), TTP (P < 0.01), and BF (P < 0.01) proved significant whereas for non-responders, all CEUS parameters proved non-significant. Conclusion CEUS performs equally to VPCT for assessment of early response to TACE in HCC by a lesion-by-lesion assessment and showed prognostic value at mid-term.

Effect of Scan Time on Perfusion and Flow Extraction Product (K-Trans) Measurements in Lung Cancer Using Low-Dose Volume Perfusion CT (VPCT)

RATIONALE AND OBJECTIVES To assess the effect of measurement time on blood flow (BF), blood volume (BV), and k-trans-values (flow extraction product) in patients undergoing volume perfusion computed tomography (VPCT) for lung cancer. MATERIALS AND METHODS This prospective study was approved by our local Research Ethics Committee and informed consent was obtained in all patients. Between December 2009 and December 2010, 75 VPCT scans were obtained in 54 consecutive patients (15 women, 39 men) with histologically confirmed lung cancer. A 64-second VPCT of the tumor (80 kV, 60 mAs) using 128 × 0.6-mm collimation, 6.9-cm z-axis coverage and a total of 26 volume measurements, was performed. BF, BV, and K(trans) were determined. Data evaluation was performed for different measurement times (64 seconds, 45 seconds, 39 seconds, and 36 seconds) by removing the last two, four, and five scans and repeating the analysis. A one-way repeated-measures analysis of variance was used to test for effects of measurement time on BF, BV, and k-trans and unpaired/paired Student t-tests were applied for comparisons within/between groups, respectively. RESULTS No effect of measurement time on BF values was noted (P > .05), whereas a significant decrease of BV values (at 39 seconds: 71% ± 2% of 64-second values) and a significant increase of k-trans-values (at 39 seconds: 146% ± 8% of 64-second values) were observed with progressively shortened measurement time (P < .05, respectively). Additionally, with reduced measurement time, the increase in k-trans-values was significantly more pronounced in those patient groups with higher BV (at 39 seconds: 171% ± 15% versus 120% ± 3% of 64-second measurements), and those with lower k-trans (at 39 seconds: 167% ± 16% versus 126% ± 4% of 64-second measurements) (P < .05, respectively). CONCLUSION Whereas estimation of BF in lung cancer was independent from VPCT measurement time within the chosen ranges, approximation of both BV and k-trans was affected by measurement duration. A fixed measurement time of 40 seconds is recommended.