A comparative study on the accuracy of pedicle screw placement assisted by personalized rapid prototyping template between pre- and post-operation in patients with relatively normal mid-upper thoracic spine

Purpose

The aim of this study was to assess the accuracy of rapid prototyping drill template technique for placing pedicle screws in the mid-upper thoracic vertebrae in clinics.

Methods

151 consecutive patients underwent thoracic instrumentation and fusion for a total of 582 pedicle screws placed in the mid-upper thoracic vertebrae. Using computer software, the authors constructed drill templates that fit onto the posterior elements of the mid-upper thoracic vertebrae with drill guides designed to instrument the pedicles. The start point and three dimensional location of the planned and inserted screws were measured and compared.

Results

Grading of the CT scans revealed 559 (96.1 %) out of 582 screws completely within the desired pedicle. The direction of pedicle violation included 5 medial, 2 airball, and 16 lateral. The paired t test suggested that these results were statistically significant in more than half of the locations (T1-left-TA(P = 0.024), T2-left-SA(P = 0.031), T3-left-SA(P = 0.014), T4-left-TA(P = 0.004), T5-left-TA(P = 0.034), T7-left-TA(P = 0.000). T1-right-TA(P = 0.049), T2-right-TA(P = 0.044), T3-right-TA(P = 0.014), T5-right-TA(P = 0.013)). The paired t-test suggested that these results were statistically significant at several locations (T4-left-Δy(P = 0.041), T5-left-Δx(P = 0.016), T3-right-Δy(P = 0.015)).

Conclusion

Use of a rapid prototyping drill template to assist in the placement of mid and upper thoracic pedicle screws may lead to increased accuracy. This patient specific technology must be combined with an understanding of the patients’ anatomy and carefully secured to the posterior elements intraoperatively to avoid nerve or vascular complications.

     

Oncologic and Perioperative Outcomes Following Selective Application of Laparoscopic Pancreaticoduodenectomy for Periampullary Malignancies

Background

Data are sparse regarding patient selection criteria or evaluating oncologic outcomes following laparoscopic pancreaticoduodenectomy (LPD). Having prospectively limited LPD to patients with resectable disease defined by National Comprehensive Cancer Network (NCCN) criteria, we evaluated perioperative and long-term oncologic outcomes of LPD compared to a similar cohort of open pancreaticoduodenectomy (OPD).

Methods

Consecutive patients (November 2010–February 2014) undergoing pancreaticoduodenectomy (PD) for periampullary adenocarcinoma were reviewed. Patients were excluded from further analysis for benign pathology, conversion to OPD for portal vein resection, and contraindications for LPD not related to their malignancy. Outcomes of patients undergoing LPD were analyzed in an intention-to-treat manner against a cohort of patients undergoing OPD.

Results

These selection criteria resulted in offering LPD to 77 % of all cancer patients. Compared to the OPD cohort, LPD was associated with significant reductions in wound infections (16 vs. 34 %; P?=?0.038), pancreatic fistula (17 vs. 36 %; P?=?0.032), and median hospital stay (9 vs. 12 days; P?=?0.025). Overall survival (OS) was not statistically different between patients undergoing LPD vs. OPD for periampullary adenocarcinoma (median OS 27.9 vs. 23.5 months; P?=?0.955) or pancreatic adenocarcinoma (N?=?28 vs. 22 patients; median OS 20.7 vs. 21.1 months; P?=?0.703).

Conclusions

The selective application of LPD for periampullary malignancies results in a high degree of eligibility as well as significant reductions in length of stay, wound infections, and pancreatic fistula. Overall survival after LPD is similar to OPD.

     

Adrenomedullin is increased in the portal circulation during chronic sepsis in rats

BACKGROUND: A clinical hallmark of sepsis is an early, hyperdynamic cardiac phase (increased cardiac output) that degrades to a hypodynamic phase, which results in poor gut perfusion and subsequent gastrointestinal (GI) hypoxemia, tissue ischemia, necrosis and loss of gut barrier function. Studies in rat cecal-ligation and puncture suggest that the potent vasodilator adrenomedullin (AM) might initiate or maintain the hypodynamic phase. We hypothesize that AM expression is increased in acute Escherichia coli bacteremia and chronic E coli-Bacteroides fragilis sepsis. METHODS: Acute bacteremia: male Sprague-Dawley rats were anesthetized (urethane/alpha-chloralose), tracheotomized, and cannulated for monitoring blood pressure (MABP) and heart rate (HR) and for infusion of E coli (10(9) colony-forming units [CFU] E coli per 1 mL normal saline) and blood sampling. Arterial blood was withdrawn for arterial blood gas (ABG) measurements every 60 minutes. After 6 hours, we harvested lung, liver, kidney, spleen, and small intestine tissue samples and drew arterial and portal blood for AM enzyme-linked immunosorbent assay (ELISA). Chronic sepsis: a sterile gauze pad was implanted and animals recovered for 5 days. Twenty-four hours (10(9) CFU E coli and 10(9) CFU B fragilis per 1 mL normal saline; 1 injection) or 72 hours (2 injections) after the inoculation of the back sponge, rats were anesthetized, intubated, and cannulated as above. MABP, HR, and ABG were measured for 1 hour before tissue and serum harvest for AM ELISA. RESULTS: Sepsis increased HR and MABP in all groups. Acute sepsis caused a respiratory alkalosis and pH was also elevated in chronic sepsis. Serum AM levels were increased in all groups compared with baseline and remained elevated at every time point, but were not different between saline controls and septic animals at any time point, except for the portal serum from the 72-hour chronic sepsis, which was elevated. CONCLUSIONS: These data suggest that surgical manipulation alone is sufficient to stimulate AM secretion, most probably from endothelial cells. While the AM levels were decreasing at 72 hours compared with 6 hours or 24 hours in the arterial blood and the saline control portal blood, it remained elevated in the septic portal samples, suggesting that the sepsis-induced increase of AM was derived from the gut by a different mechanism than that which elevated arterial serum levels.     

Comparison of rates and risk factors for development of anaemia and erythropoiesis-stimulating agent utilization after radical or partial nephrectomy

Study Type – Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? The consequences and significance of iatrogenically‐induced CKD are poorly understood. Most data regarding risk of CKD and its complications are inferred from the medical literature. This is the first study to examine impact of surgical management of renal masses on development of anaemia. Patients who underwent radical nephrectomy had a significantly higher incidence of anaemia and ESA utilization than a contemporary well‐matched cohort that underwent partial nephrectomy. The results obtained add to the growing body of data supporting the use of partial nephrectomy in the management of clinically appropriate renal masses.

OBJECTIVE

• ? To examine the incidence of and risk factors for the development of anaemia and erythropoiesis‐stimulation agent (ESA) treatment in patients undergoing radical nephrectomy (RN) and partial nephrectomy (PN) because anaemia is a significant cause of morbidity in chronic kidney disease.

PATIENTS AND METHODS

• ? The study comprised a retrospective review of 905 patients (610 RN/295 PN; mean age, 57.5 years; mean follow‐up, 6.4 years) who underwent surgery for renal tumours at two institutions from July 1987 to June 2007.
• ? Demographics, disease characteristics and pre‐ and postoperative (i.e. renal function, metabolic parameters, anaemia and ESA treatment) were recorded.
• ? Data were analyzed within subgroups based on treatment (RN vs PN).
• ? Multivariate analysis was conducted to determine the risk factors for developing anaemia after surgery.

RESULTS

• ? Tumour size (cm) was significantly larger for RN (RN 7.0 vs PN 3.7; P < 0.001). No significant differences were noted with respect to demographics and preoperative anaemia (RN 16.4% vs PN 18.6%; P= 0.454) and ESA‐treatment (RN 0.7% vs PN 1.4%; P= 0.499).
• ? After surgery, significantly less de novo anaemia (PN 4.1% vs RN 17.5%; P < 0.001) and ESA utilization (PN 2.7% vs RN 13.4%; P < 0.001) occurred in the PN cohort.
• ? Multivariate analysis showed that age ≥60 years (odds ratio, OR, 1.62; P= 0.008), African American ethnicity (OR, 2.30; P < 0.001), smoking (OR, 1.60; P= 0.013), glomerular filtration rate (GFR) <60 mL/min/1.73 m² (OR, 4.09; P < 0.001), ≥1+ proteinuria (OR, 2.19; P < 0.03), metabolic acidosis (OR, 4.08; P= 0.007) and RN (OR, 2.58; P < 0.001) were significantly associated with de novo anaemia.

CONCLUSIONS

• ? Patients who underwent RN had a significantly higher prevalence of anaemia and ESA‐treatment compared to a well‐matched cohort that underwent PN.
• ? In addition to RN, age ≥60 years, African American ethnicity, history of smoking, GFR < 60 mL/min/1.73 m², proteinuria and metabolic acidosis were associated with developing anaemia.

     

Evaluation of multicoil breast arrays for parallel imaging

Purpose:

To evaluate three multicoil breast arrays for both conventional and SENSE‐accelerated imaging.

Materials and Methods:

Two commercially available 8‐element coils and a prototype 16‐element coil were compared. One 8‐element array had adjustable coils located next to the breast tissue and the other had a fixed coil arrangement; both were designed to allow parallel imaging in the left–right direction. The 16‐element coil was designed to have coil sensitivity variation in both the left–right and superior–inferior directions, and also had adjustable coils. Their performance was assessed in terms of signal‐to‐noise ratio (SNR), g‐factor, and uniformity with a custom‐built phantom.

Results:

The 16‐element array with adjustable coils provided the highest SNR, while the 8‐element coil with a fixed coil arrangement had the best uniformity. All coils performed well for SENSE acceleration in the left–right direction. The 8‐element coils did not have the capability for acceleration in the superior–inferior direction across the whole volume. The 16‐element coil enabled acceleration in the superior–inferior direction in addition to the left–right direction.

Conclusion:

Smaller, adjustable coil elements located next to breast tissue can provide greater SNR than larger, fixed coil elements. A multicoil breast array with high intrinsic SNR and low g‐factors enables high‐quality parallel imaging. J. Magn. Reson. Imaging 2010; 31: 328–338. © 2010 Wiley‐Liss, Inc.     

Esophageal strictures in children: treatment by serial balloon catheter dilatation

Grüntzig balloon catheters were used to dilate ten esophageal strictures in eight infants and children. Five infants who had anastomotic strictures following esophageal atresia repair gained complete resolution of their strictures, usually after one or two dilatations. Three older children who had strictures following esophageal re-operation or reconstruction required longer courses of dilatations to achieve consistent esophageal patency. The technique failed in two chronic strictures of two and one-half and nine years' duration. Balloon catheter dilatation, begun in the early postoperative period, is a safe, effective method for dilating esophageal strictures.     

RASER: a new ultrafast magnetic resonance imaging method.

A new MRI method is described to acquire a T(2)-weighted image from a single slice in a single shot. The technique is based on rapid acquisition by sequential excitation and refocusing (RASER). RASER avoids relaxation-related blurring because the magnetization is sequentially refocused in a manner that effectively creates a series of spin echoes with a constant echo time. RASER uses the quadratic phase produced by a frequency-swept chirp pulse to time-encode one dimension of the image. In another implementation the pulse can be used to excite multiple slices with phase-encoding and frequency-encoding in the other two dimensions. The RASER imaging sequence is presented along with single-shot and multislice images, and is compared to conventional spin-echo and echo-planar imaging sequences. A theoretical and empirical analysis of the spatial resolution is presented, and factors in choosing the spatial resolution for different applications are discussed. RASER produces high-quality single-shot images that are expected to be advantageous for a wide range of applications.     

Utilization of diagnostic medical imaging: comparison of radiologist referral versus same-specialty referral

PURPOSE: To retrospectively compare the frequency with which patients underwent diagnostic medical imaging procedures during episodes of outpatient medical care according to whether their physicians referred patients for imaging to themselves and/or physicians in their same specialty or to radiologists. MATERIALS AND METHODS: Institutional review board approval was not necessary for this HIPAA-compliant study. An insurance claims database from a large national employer-based health plan was obtained. Claims data from 1999-2003 were grouped into episodes of care for six conditions: cardiopulmonary disease, coronary and/or cardiac disease, extremity fracture, knee pain, intraabdominal malignancy, and stroke. For each condition, each referring physician's behavior was categorized as either "same-specialty referral" or "radiologist referral" on the basis of that physician's entire history of imaging referrals for the condition. The frequency with which patients underwent diagnostic medical imaging procedures during episodes of care was compared according to whether their physicians referred patients for imaging to themselves and/or same-specialty physicians or to radiologists. Rates were compared by using chi(2) tests, and logistic regression was used to compare utilization rates, with patient age and number of comorbidities as covariates. RESULTS: For the conditions evaluated, physicians who referred patients to themselves or to other same-specialty physicians for diagnostic imaging used imaging between 1.12 and 2.29 times as often, per episode of care, as physicians who referred patients to radiologists (P < .005 for all comparisons). Adjusting for patient age and comorbidity, the likelihood of imaging was 1.196-3.228 times greater for patients cared forby same-specialty-referring physicians. CONCLUSION: Same-specialty-referring physicians tend to utilize imaging more frequently than do physicians who refer their patients to radiologists. These results cannot be explained by differences in case mix (because analyses were performed within six specific conditions of interest), patient age, or comorbidity.     

Coronal oblique turbo STIR imaging of the sacrum and sacroiliac joints at routine MR imaging of the lumbar spine

The objective of the study was to evaluate the clinical impact of coronal oblique imaging of the lumbrosacral junction and the sacrum at initial presentation for MR imaging of the lumbar spine in patients presenting with low back pain or sciatic pain. Two hundred and sixty consecutive patients attending for MRI of the lumbar spine underwent simultaneous coronal oblique turbo short tau inversion recovery (STIR; TR 2500, TE 40, TI 150, echo train length 7, number of scan acquisitions 2) imaging of the sacrum and the sacroiliac joints with a field of view of 30-cm and 3-mm slices (acquisition time 3 min and 20 s). Images were reviewed by two experienced radiologists to determine the cause of back pain, with and without images of the sacrum and sacroiliac joints. The added value of the additional sequence was assessed. Correlation was made with surgery, response to nerve root injection or clinical follow-up at 3 months. Subgroup analysis was performed to determine if patient stratification according to sex or symptoms would be useful. In total, in 19 of 260 patients (7.3%), abnormalities were identified at coronal STIR imaging. In 7 of 260 patients (2.7%), pathology was identified in the sacrum thought to account for back pain, altering the diagnosis made on the standard sequences. These diagnoses were sacroiliitis (n=2), sacral stress fracture (n=1), degenerative sacroiliac joints (n=1), degenerative accessory articulation between the lumbar spine and the sacrum (n=1), Tarlov cyst of nerve root (n=1) and retroverted uterus causing sciatic pain (n=1). Patient stratification according to sex or the presence or absence of sciatic symptoms was not useful in predicting the added benefit of the additional sequence. Routine coronal STIR imaging of the sacrum as part of lumbar spine MRI improves assessment of patients presenting with low back pain or sciatica in only a small number of patients.