MRI-based torsion measurement of the lower limb is a reliable and valid alternative for CT measurement: a prospective study.

PURPOSE: The aim of this study was to compare MRI-based torsion measurements of the lower limb to a well-established CT-based assessment in a prospective inter- and intraindividual approach. METHODS: A total of 26 patients (age 28.8 years ± 11.0) were enrolled beginning in January 2021 until August 2022. Inclusion criteria were the clinical indication for torsion measurement of the lower limb. CT and MRI imaging were performed with a standard operating procedure, to ensure that all patients were examined in a standardized position. The examinations were planned on a coronal scout view based on prominent anatomical landmarks. Femoral and tibial torsion were measured individually. Torsion measurements were analysed twice: immediately after examination and after 3 weeks. Subsequently, intra-rater and parallel test reliability was calculated accordingly. RESULTS: High significant results for CT and MRI measurements for both tibia (MRI: r = 0.961; p ≤ 0.001; CT: r = 0.963; p ≤ 0.001) and femur (MRI: r = 0.980; p ≤ 0.001; CT: r = 0.979; p ≤ 0.001) were obtained by calculated intra-rater reliability, showing that measurements were highly consistent for MRI and CT, respectively. Parallel test reliability for time point 1 as well as time point 2 was also highly significant and ranged from r = 0.947 to r = 0.972 (all with p ≤ 0.001, respectively) for both tibia and femur, showing a high concordance between the two measurements. CONCLUSION: Measurement of tibial as well as femoral torsion was comparable for CT and MRI measurement. Therefore, this study supports MRI measurement as an equivalent alternative for CT measurement concerning torsional malalignment to reduce exposure to radiation. LEVEL OF EVIDENCE: Level II.

Patient response to osteotomy around the knee joint at one year post-operation-fulfilment of expectations and current health status.

INTRODUCTION: The aim of this study was to investigate patient satisfaction and fulfilment of expectations after osteotomy around the knee at one year postoperatively, using patient-related outcome measures. MATERIALS AND METHODS: From the initial sample of 264 patients, a total of 132 patients (age 48y ± 11) were enrolled in this prospective study (response rate 49.3%). Data were collected using the Hospital For Special Surgery-Knee Surgery Expectations Survey (HFSS-KSES), items for satisfaction and the Knee injury and Osteoarthritis Outcome Score (KOOS) measures. At one year postoperative follow-up, an individualized questionnaire asked whether the specific person-related expectations had been fulfilled. RESULTS: Satisfaction was high with 83.2% of all participants at one year after surgery. A total of 78% of patients stated they would decide to do the surgery again. This decision was significantly associated with satisfaction, younger age and better KOOS scores scales before surgery for pain, activity and sports. We found high correlations between satisfaction and fulfilment of expectations for the HFES-KSES. Fulfilment of expectations one year after surgery was significantly associated with significant improvements in KOOS scales at one year post-operation. Expectations (1) "to get the knee back to normal status", (2) "improve ability to squat", (3) "improve ability to run", (4) "improve ability to kneel" had been fulfilled worst. A multiple linear regression model for satisfaction had an R2 = 0.797 of the variance. The most influential was the variable fulfilment of "maintain health" that had 70.7% of variance. CONCLUSIONS: The fulfilled expectation concerning an improvement of the ability to maintain health was the most influential parameter for satisfaction at one year post-osteotomy. Patients with better health status of the knee and younger age rated the surgery to be more positive and were also more likely to do the surgery again. This provides an indication for an earlier intervention, before the knee and overall health status becomes more detrimental. LEVEL OF EVIDENCE: Level II (Therapeutic study).

Overweight patients benefit from high tibial osteotomy to the same extent as patients with normal weights but show inferior mid-term results.

PURPOSE: The purpose of this prospective study was to analyze the impact of obesity on the clinical and radiological outcomes 6 years after open-wedge high tibial osteotomy (HTO). METHODS: A total of 120 prospectively recorded patients with medial compartment osteoarthritis underwent open-wedge HTO between 2008 and 2011. The study cohort was frequently examined over a minimum of a 6-year follow-up. The cohort was divided into three groups according to body mass index (BMI): normal weight patients (BMI < 25 kg/m2), pre-obese patients (BMI 25-30 kg/m2) and obese patients (BMI > 30 kg/m2). Clinical and functional outcomes (Oxford Knee Score, Hospital for Special Surgery Score, Lequesne Score, Tegner Activity Scale), subjective health-related quality of life (SF-36), change in mechanical limb alignment (mTFA) as well as conversion to unicompartmental or total knee arthroplasty (TKA) were evaluated. To compare clinical scoring between the groups, univariate variance analysis was applied. Changes in outcome variables over time were analyzed with dependent t tests. RESULTS: From 120 patients, 85 were followed-up over a 6.7-year period on average (6-11.8 years) after HTO. The mean BMI was 28.6 ± 4.6 kg/m2. Each group showed a significant pre- to postoperative increase in all recorded scores (p < 0.05). In absolute terms, both mental and clinical scores of overweight patients did not reach the peak values of the normal weighted population during the period of observation. There was a conversion to TKA in 10.5% after an average of 50.1 ± 25.0 months following surgery. A total of five complications occurred without significant differences (BMI < 25: n = 1, BMI 25-30: n = 2, BMI > 30: n = 2; n.s.). There was a mean pre- to postoperative (six weeks after surgery) correction difference of 6.9° ± 3.2° (mTFA) with higher loss of correction over time in overweight patients. CONCLUSION: In terms of clinical outcome and health-related quality of life, overweight patients may receive a benefit from open-wedge HTO to the same extent as patients with normal weights and show similar complication rates. However, they have inferior preoperative clinical and functional results and mid-term results after open-wedge HTO compared to patients with normal weights. LEVEL OF EVIDENCE: Level III.

3D geometry of femoral reaming for bone graft harvesting.

The reamer-irrigator-aspirator (RIA) technique allows to collect large bone graft amounts without the drawbacks of iliac crest harvesting. Nevertheless, clinical cases with occurrence of femur fractures have been reported. Therefore, this study aimed to systematically investigate the three-dimensional geometry of the reamed bone as a function of the reaming diameter and its influence on the associated potential fracture pattern. Forty-five intact fresh-frozen human cadaveric femora underwent computed tomography (CT). They were randomized to three groups (n = 15) for reaming at a diameter of either 1.5 mm (Group 1), 2.5 mm (Group 2) or 4.0 mm (Group 3) larger than their isthmus using RIA. Reaming was followed by a second CT scan, biomechanical testing until failure and a third CT scan. All CT scans of each femur were aligned via rigid registration, and fracture lines were visualized. Subsequently, a decrease in wall thickness, cross-sectional area, and harvested bone volume have been evaluated. The total volume of the bone graft was significantly higher for Group 3 (7.8 ± 2.9 ml) compared to Group 1 (2.9 ± 1.1 ml) and Group 2 (3.0 ± 1.1 ml). The maximal relative decrease of the wall thickness was located medially (72.7%) in the third (61.4%), fourth (18.2%) and second (9.1%) eighth for all groups. As the diameter of the reaming increased, an overlap of the fracture line with the maximal relative decrease in wall thickness and a maximal average relative decrease of the cross-sectional area became more frequent. This suggests that a reaming-associated fracture is most likely to occur in this region.

Radiation Dose Reduction in CT Torsion Measurement of the Lower Limb: Introduction of a New Ultra-Low Dose Protocol.

This study analyzed the radiation exposure of a new ultra-low dose (ULD) protocol compared to a high-quality (HQ) protocol for CT-torsion measurement of the lower limb. The analyzed patients (n = 60) were examined in the period March to October 2019. In total, 30 consecutive patients were examined with the HQ and 30 consecutive patients with the new ULD protocol comprising automatic tube voltage selection, automatic exposure control, and iterative image reconstruction algorithms. Radiation dose parameters as well as the contrast-to-noise ratio (CNR) and diagnostic confidence (DC; rated by two radiologists) were analyzed and potential predictor variables, such as body mass index and body volume, were assessed. The new ULD protocol resulted in significantly lower radiation dose parameters, with a reduction of the median total dose equivalent to 0.17 mSv in the ULD protocol compared to 4.37 mSv in the HQ protocol (p < 0.001). Both groups showed no significant differences in regard to other parameters (p = 0.344-0.923). CNR was 12.2% lower using the new ULD protocol (p = 0.033). DC was rated best by both readers in every HQ CT and in every ULD CT. The new ULD protocol for CT-torsion measurement of the lower limb resulted in a 96% decrease of radiation exposure down to the level of a single pelvic radiograph while maintaining good image quality.

In vivo test of a radiography-based navigation system for control of derotational osteotomies.

Malalignment of the femur is a frequently encountered problem in orthopaedics entailing manifold consequences for the affected patients. Corrective osteotomies, necessary to restore the physiological and anatomical relationships, face great challenges due to no existing reliable gold standard for intraoperative control of torsional malalignment. The aim of this study was to test a novel radiography-based navigation tool for control of derotational osteotomies in a clinical environment. In a first-and preliminary-case-controlled study on 12 patients (level 3 of evidence), the achieved torsional correction measured with implementation of the navigation tool was compared with measurements from pre- and postoperative computed tomography (CT) scans. The navigation tool was able to acquire and process all relevant data and capture possible malrotation during surgery with only little deviations of 1.61° ± 0.86° (mean ± standard deviation) from the measurements based on CT scans. Next, the system will be used to assist surgeons for more precise treatment avoiding maltorsion after derotational osteotomies.

Improving the accuracy of patient positioning for long-leg radiographs using a Taylor Spatial Frame mounted rotation rod.

INTRODUCTION: Long-leg radiographs are used to plan and supervise the correction of bone deformity in patients treated with the Taylor Spatial Frame (TSF). Often radiographs are performed with malpositioning of the limb leading to wrong alignment measurements. The aim of this retrospective study was to show the usefulness of a simple device which might enhance the reproducibility of limb rotation on long-leg radiographs. MATERIALS AND METHODS: We included 20 consecutive patients with TSF treatment and at least three long-leg radiographs (4.9 ± 1.3). Eight out of 20 patients received radiographs with the help of a rotation rod (device with two clamps and a carbon tube). It is placed at the most frontal tab of the reference ring while conducting the radiograph. By this means, limb rotation can be controlled. To show the usefulness of this device, two observers measured the relation of the distances between the middle of the reference ring to the medial and lateral fourth hole on the reference ring (TSF-RR). The standard deviation and range of the TSF-RR of all radiographs for each patient was calculated and compared between patients without and with the rotation rod. RESULTS: The standard deviations of TSF-RR in patients without the rotation rod was significantly higher compared to patients with rotation rod (observer 1: p = 0.0228, observer 2: p = 0.0038). Also, the range of the TSF-RR within one patient is significant higher (observer 1: p = 0.0279, observer 2: p = 0.0038) in patients without the rotation rod compared to patients with the rotation rod. CONCLUSIONS: The variability of rotation on radiographs was lower with the rotation rod. Therefore, more reproducible and better comparable radiographs can be conducted. Radiologic exposure might be reduced as repetition of wrongly positioned limbs on radiographs are less frequent.

Influence of the Reamer-Irrigator-Aspirator diameter on femoral bone strength and amount of harvested bone graft - a biomechanical cadaveric study.

BACKGROUND: Treatment of large bone defects is still related to unsolved problems in orthopaedic trauma surgery. Minimally invasive intramedullary reaming with the use of the Reamer-Irrigator-Aspirator (RIA) device allows autograft harvesting of large bone graft amounts from the medullary canal of the femur. The aim of this study was to investigate the influence of RIA diameter on femoral bone strength and amount of harvested bone graft in a human cadaveric model. METHODS: Forty-five pairs human cadaveric femora were randomized to 3 paired groups with 15 pairs each. One femur of each pair was reamed with RIA at a diameter of either 1.5 mm (group 1), 2.5 mm (group 2) or 4.0 mm (group 3) larger than its isthmus, whereas its contralateral femur was left intact without reaming. The amount of harvested bone graft was determined for each specimen and all femora were destructively tested in internal rotation under 750 N axial compression to calculate their torsional stiffness and torque at failure. RESULTS: Significant reduction in torsional stiffness was detected after reaming in group 3 (p = 0.03) in contrast to groups 1 and 2 where no such significant reduction was observed (p ≥ 0.34). Torque at failure was significantly reduced after reaming in all 3 groups (p ≤ 0.04). Collected bone graft amount in group 3 was significantly bigger compared to groups 1 and 2 (p ≤ 0.04). CONCLUSIONS: Reaming with RIA diameter of 4.0 mm larger than the isthmus of the femur seems to influence considerably its torsional stiffness, however, it allows harvesting of a significantly bigger bone graft amount.

The influence of screw length on predicted cut-out failures for proximal humeral fracture fixations predicted by finite element simulations.

BACKGROUND: The aim of this study was to identify the effect of screw length on predictions of fixation failure in three-part proximal humeral fractures using a finite element-based osteosynthesis modelling toolkit. METHODS: A mal-reduced unstable three-part AO/OTA 11-B3.2 fracture with medial comminution was simulated in forty-two digitally processed proximal humeri covering a spectrum of bone densities and fixed with the PHILOS plate using three distal and six proximal locking screws. Four test groups were generated based on the screw tip to joint surface distance (TJD), with all proximal screws being shortened from 4 mm TJD to be 8, 12 or 16 mm TJD. Average bone strains around the screw tips, correlating with biomechanical cyclic cut-out-type failure, were evaluated in three physiological loading protocols representing simple shoulder motions. Six further groups were tested, where five of the proximal screws were inserted to 4 mm TJD and the sixth screw to 8 mm TJD. RESULTS: Exponential increases in the predicted risk of fixation failure were seen with increased tip-to-joint distances (p < 0.001). When one of the proximal screws was placed 8 mm from the joint, with the remaining five at 4 mm distance, significant increases (p < 0.001) were registered in the strains around the screw tips in all except the two superior screws. This effect was maximal around the calcar screws (p < 0.001) and for lower density samples (p < 0.001). CONCLUSIONS: These results suggest that longer screws provide reduced risk of cut-out failure, i.e. distalisation and/or varisation of the head fragment, and thus may decrease failure rates in proximal humeral fractures treated with angular stable plates. These findings require clinical corroboration and further studies to investigate the risk of screw perforation.

Patients' expectations of osteotomies around the knee are high regarding activities of daily living.

PURPOSE: This study was conducted to investigate patients' expectations on high tibial osteotomies, distal femur osteotomies, and double-level osteotomies in different health-related domains. It was hypothesized that expectations are high in terms of capacity to work, pain relief, and restoring knee function. METHODS: A total of 264 patients (age 47 years ± 11 years) were enrolled in this study from March 2015 until May 2016 in seven specialized orthopaedic surgery departments. Data were collected via the Knee injury and Osteoarthritis Outcome Score, the Hospital for Special Surgery-Knee Surgery Expectations Survey, and a ten-item (non-validated) questionnaire to specifically ask about expectations of osteotomies around the knee 24-48 h prior to surgery. In addition, self-efficacy was assessed. Parametric tests were used to test the hypothesis. RESULTS: Knee injury and Osteoarthritis Outcome Score test results showed that all patients suffered because of their knee impairments prior to surgery. All participants had high expectations in all aspects regarding the surgical outcome: on a four-point Likert scale ranging from 1 (very important) to 4 (not important), all mean values were between 1.2 and 1.7. For patients who had a demanding physical work, the ability to keep a stressful working posture was more important than for other patients (i.e. to kneel, to squat). Furthermore, preoperative lower quality of life was associated with higher expectations concerning improving the ability to walk, to achieve improvements in activities of daily living and social well-being. CONCLUSIONS: Patients' expectations of osteotomies around the knee are high in terms of capacity to work, pain relief, and restoring functions. The natural course of osteoarthritis and the potential need for conversion to TKA were underestimated by a substantial proportion of the study population. However, the expectation regarding survival rate is in line with the reported literature. The results of this study should assist surgeons in discussing realistic expectations when considering and counselling patients regarding osteotomies around the knee. This may help to clarify realistic expectations preoperatively and ultimately improve patients' satisfaction. LEVEL OF EVIDENCE: Therapeutic study, Level II.

EASY (endoscopic approach to the symphysis): a new minimally invasive approach for the plate osteosynthesis of the symphysis and the anterior pelvic ring-a cadaver study and first clinical results.

BACKGROUND: Minimally invasive surgical approaches to reduce approach-associated morbidity are an interdisciplinary goal in surgery. In principle, the endoscopic approach for the extraperitoneal repair of groin hernias is the minimally invasive variant of the modified Stoppa-approach, which is used for the treatment of pelvic ring injuries in traumatology. METHOD: Anatomical feasibility study regarding the plate osteosynthesis of the anterior pelvic ring via a minimally invasive variant of the modified Stoppa-approach. RESULTS: We present the minimally invasive variant of the modified Stoppa-approach in a human cadaver step by step, both photographically and radiologically. Feasibility of the plate osteosynthesis of the symphysis is presented in a patient with open book injury via the minimally invasive approach using standard laparoscopic instruments. CONCLUSION: The plate osteosynthesis of the anterior pelvic ring via the minimally invasive variant of the modified Stoppa-approach is feasible with existing standard laparoscopic instruments.

Endoscopic Approach to the Quadrilateral Plate (EAQUAL): a New Endoscopic Approach for Plate Osteosynthesis of the Pelvic Ring and Acetabulum - a Cadaver Study. / Endoscopic Approach to the Quadrilateral Plate (EAQUAL): ein neuer endoskopischer Zugang für die Plattenosteosynthese des Beckenringes und Azetabulums ­ eine anatomische Machbarkeitsstudie.

BACKGROUND: Dislocated pelvic fractures which require surgical repair are usually operated on via open surgery. Approach-related morbidity is reported with a frequency of up to 30%. The aim of this anatomical study was to prove the feasibility of endoscopic visualisation of the relevant anatomical structures in pelvic surgery and to perform completely endoscopic plate osteosynthesis of the acetabulum with available standard laparoscopic instruments. METHOD: In four human cadavers, we established an endoscopic preparation of the complete pelvic ring, from the symphysis to the iliosacral joint, including the quadrilateral plate and the sciatic nerve, and performed endoscopic plate osteosynthesis along the iliopectineal line. RESULTS: The endoscopic preparation of the complete pelvic ring and the quadrilateral plate was demonstrated step-by-step, followed by completely endoscopic plate osteosynthesis along the pelvic brim. Endoscopic, radiographic, and schematic pictures are used to illustrate the technique. CONCLUSION: The completely endoscopic preparation of the pelvic brim and the quadrilateral plate is feasible with available standard laparoscopic instruments. Moreover, plate osteosynthesis could be performed endoscopically. Further research on reduction techniques is necessary when planning to implement this technique into a clinical scenario.

Fatigue failure of plated osteoporotic proximal humerus fractures is predicted by the strain around the proximal screws.

The high rate of required reoperation indicates that treatment of fragility fractures at the proximal humerus still remains a major challenge in trauma surgery. Improved fixation approaches are needed. Several limitations of the conventional implant development process involving experimental testing could be overcome by using computer models that would allow systematic and efficient analyses. However, such models require experimental validation. This study investigated if linear elastic continuum finite element (FE) models can predict experimental fatigue failure in locking plate fixation of osteoporotic proximal humerus fractures. Three-part fractures were created in twenty fresh-frozen proximal humeri of elderly donors, stabilized with angular stable plate osteosythesis and tested to failure in a previously developed experimental setup using a cyclic loading protocol with increasing peak load. Case-specific, linear elastic FE models of the instrumented samples were created from CT images and loaded virtually by mimicking the experimental conditions. Average principal strains were evaluated in cylindrical regions around the proximal screws. Parametric sensitivity analysis was performed to investigate the effects of specific model parameters on the results. The number of cycles to failure was 10500 ± 3300 (mean ± SD, range: 3100 - 16400) and showed a strong logarithmic correlation with the average compressive principal strain around the screws (R2 = 0.90). These results suggest that the latter parameter may be used as a surrogate estimate for construct stability under cyclic loading. The computationally cheap linear elastic continuum FE analysis could be used as an efficient screening tool for optimization and development of implants. Further work is required to investigate if the findings of this study apply to other loading modes and bone-implant constructs.

Malnutrition - An underestimated factor in the inpatient treatment of traumatology and orthopedic patients: A prospective evaluation of 1055 patients.

INTRODUCTION: Suboptimal nutritional status is often observed among hospitalized patients across all medical specialties. The objective of the present study was to (1) analyze the prevalence of malnutrition in hospitalized orthopedic and trauma patients and (2) to evaluate the relationship between malnutrition and selected clinical outcomes. MATERIALS AND METHODS: The prospective field study was conducted between 06/2014 and 06/2015 in a German level I trauma center (Department of Traumatology, Septic Trauma Surgery and Arthroplasty) with a total number of 1055 patients. At hospital admission, patients were checked for malnutrition using the validated Nutritional Risk Screening (NRS). Patients at risk for malnutrition were defined as NRS≥3. Quality of life (SF-36) was assessed to evaluate the physical and mental health status prior to hospitalization. Clinical outcomes under consideration included 1) rate of adverse events, 2) length of hospitalization, and 3) mobilization after operative and conservative treatment. Patients were included independently of surgical intervention or age. RESULTS: 22.3% (235) of our patients were at risk for malnutrition (NRS≥3) while a regular nutritional status (NRS<3) was diagnosed in 77.7% (819). The highest prevalence of malnutrition was found in Septic Surgery with 31.0% (106), followed by Traumatology with 19.2% (100) and Arthroplasty with 15.1% (29). Higher prevalence of malnutrition was observed among patients with typical fractures of the elderly, such as lumbar spine and pelvis (47.4%), proximal femur (36.4%) and proximal humeral (26.7%) fractures. Furthermore, patients at risk for malnutrition showed prolonged hospitalization (13.7±11.1 vs. 18.2±11.7days), delayed postoperative mobilization (2.2±2.9 vs. 4.0±4.9days) and delayed mobilization after conservative treatment (1.1±2.7 vs. 1.8±1.9days). A statistically significant correlation of NRS with each parameter (Spearman's rank correlation, p<0.05) was observed. The incidence of adverse events in patients at risk for malnutrition was statistically significantly higher compared to that of patients with a regular nutritional status (37.2% vs. 21.1%, p<0.001). CONCLUSIONS: Malnutrition is widespread regarding hospitalized patients in the field of orthopedic and trauma surgery and results in suboptimal clinical outcome. It should be considered as an important factor that significantly contributes to delayed recovery. Especially elderly trauma patients and patients suffering from postoperative infections should be monitored carefully during hospitalization.

Health-related quality of life and clinical outcomes following medial open wedge high tibial osteotomy: a prospective study.

BACKGROUND: Open wedge high tibial osteotomy (HTO) is an established method for the treatment of patients with varus malalignment and medial compartment osteoarthritis. In these patients, health-related quality of life (HRQL) can be improved by using this procedure. The purpose of the present study consisted in evaluating HRQL up to 18 months after HTO, comparing the results to values of the German normal population, and in analyzing the impact of preoperative HRQL on the postoperative clinical result. It was hypothesized that normal values in physical and mental health can be achieved within 18 months after operation. STUDY DESIGN: Prospective case series. LEVEL OF EVIDENCE: IV. METHODS: 120 patients were included in this prospective case series from 12/2008 to 12/2011. All patients underwent open wedge HTO without a bone graft using the TomoFix(TM) plate. HRQL was assessed by using the SF-36 questionnaire, preoperatively, as well as 6, 12, and 18 months postoperatively. Regular scoring, norm-based scaling, and the physical and mental component summary scores (PCS and MCS) were evaluated. Clinical outcome was assessed by using Lequesne, Lysholm, HSS and IKDC Score. RESULTS: HRQL could be described in 96 patients. The PCS of HRQL showed a statistically significant pre- to postoperative improvement (30.2 ± 13.4 to 45.9 ± 13.5 after 18 months). A reduced preoperative mental component summary score (MCS) resulted in lower values of each clinical score (p < 0.05) and in a prolonged duration of incapacity for work (MCS < 50:15.0 ± 12.8 weeks, vs. MCS ≥ 50: 9.1 ± 4.8 weeks, p < 0.05). MCS values improved from the pre- to postoperative measurements and comparable values to the normal population were reached already within 6 months after surgery (46.0 ± 14.9 pre-operatively and 48.5 ± 13.7 after 6 months), and after 18 months even a score of 49.5 ± 12.4 was achieved. CONCLUSION: Lower preoperative mental component score results in reduced postoperative clinical outcome and prolonged duration of incapacity for work after HTO. In contrast to PCS, MCS showed comparable values to the normal population within 6 months after HTO.

Midtreatment evaluation of lymphoma response to chemotherapy by volume perfusion computed tomography.

OBJECTIVE: The aim of this study was to search for chemotherapy-induced perfusion changes of diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma at midtreatment versus baseline volume perfusion computed tomography (VPCT). METHODS: Forty-five consecutive patients with untreated diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma received VPCT examinations of the tumor bulk at baseline and during chemotherapy (midtreatment). Blood flow (BF), blood volume (BV), and transit constant (K-trans) were determined. Treatment response was categorized according to the Cheson criteria into complete or partial remission and stable or relapsed/progressive disease. RESULTS: Midtreatment follow-up showed a reduction in BF, BV, and K-trans in all lymphoma subtypes compared with baseline. The reduction in BV was less pronounced in larger tumors. Notably, BF, BV, and K-trans decreased in the responders (complete remission/partial remission) when compared with the nonresponders (stable or relapsed/progressive disease). Less than 10% reduction in BF was shown to be the best VPCT criterion for the identification of nonresponse. CONCLUSIONS: Chemotherapy-induced perfusion changes in responders are recognizable at midtreatment VPCT.